A [[TiCl2(isodiCp)]2(mu-O)] dimer and a twinned cyclic [TiCl(isodiCp)(mu-O)]4 tetramer

The mu-oxo dimer mu-oxo-bis[dichloro[(1,2,3,3a,7a-eta)- 4,5,6,7-tetrahydro-4,7-methano-1H-indenyl]titanium], [Ti2Cl4(mu-O)(C10H11)2], and the mu-oxo cyclic tetramer, cyclo-tetra-mu-oxo-tetrakis[chloro[(1,2,3,3a,7a-eta)-4,5,6,7-tetrahydro- 4,7-methano-1H-indenyl]titanium], [Ti4Cl4(mu-O)4(C10H11)4], have been synthesized by electrophilic attack of TiCl4 on the exo-trimethylsilyl derivative of isodiCp (isodiCp is the isodicyclopentadienide anion or 4,5,6,7-tetrahydro-4,7-methano-1H-indene) in the presence of trace amounts of moisture. Both structures are endo isomers, with each Ti atom bonded in a eta 5 manner to the Cp ring of the isodiCp ligand. Both display a slight bending of the isodiCp group about the bond common to the Cp ring and the norbornane fragment, such that the norbornane group is displaced in the direction away from the Ti atom. The dihedral angles which describe this bending are 9.0 (3) and 10.2 (3) degrees for the dimer, and 9.2 (2) degrees for the tetramer. The dimer contains a bent Ti-O-Ti angle of 159.5 (2) degrees. The tetramer forms tetragonal crystals, which are twinned by merohedry on the (110) plane. The tetramer molecule contains a crystallographic 4 axis, with the Ti atoms linked by the O atoms in a mu-oxo manner to form an eight-membered ring.

endo and exo isomers of isodicyclopentadienyltrichlorotitanium

The diastereomeric endo and exo isomers of the title complex, [TiCl3(C10H11)], have been synthesized by electrophilic attack of TiCl4 on the exo- or endo-trimethylsilyl derivative of isodiCp (isodiCp = isodicyclopentadiene). This reaction proceeds with net inversion of configuration to give exclusively either the endo- or exo-(isodiCp)TiCl3 compound. Although the two isomers have similar unit-cell constants, they crystallize in different space groups. The endo complex, (2), is in Pbcm with a crystallographic mirror plane, while the exo complex, (4), is in Pca2(1) with pseudo-mirror symmetry. Both molecules display a distorted tetrahedral geometry about the Ti atom. Each Ti atom is bonded in a eta(5) manner to the Cp ring of the isodiCp ligand, with Ti--ring centroid distances of 2.031 (2) and 2.013 (2) A for (2) and (4), respectively. A slight bending of the isodiCp ligand about the bond shared by the Cp ring and the norbornane fragment is observed in both structures. The determination of the absolute structure of (4) defines the directionality of the packing along the polar c axis.

Rhenium Polyhydride Complexes Containing PhP(CH(2)CH(2)CH(2)PCy(2))(2) (Cyttp): Protonation, Insertion, and Ligand Substitution Reactions of ReH(5)(Cyttp) and Structural Characterization of ReH(5)(Cyttp) and [ReH(4)(eta(2)-H(2))(Cyttp)]SbF(6)

Several new polyhydride complexes of rhenium containing the tridentate phosphine PhP(CH(2)CH(2)CH(2)PCy(2))(2) (Cyttp) were synthesized and characterized by (1)H and (31)P{(1)H} NMR and IR spectroscopy. The solid state structure of the previously reported ReH(5)(Cyttp) (1) was determined by X-ray crystallography. 1 crystallizes in the space group P2(1)/m with the following unit cell parameters: a = 8.582(2) Å, b = 19.690(2) Å, c = 10.800(2) Å, beta = 95.57(1) degrees, and Z = 2. The molecule adopts a classical polyhydride, triangulated dodecahedral structure, with the three phosphorus atoms and one hydrogen atom occupying the B sites, and the remaining hydrogen atoms occupying the A sites. 1 is protonated by HSbF(6) (or HBF(4)) to yield [ReH(4)(eta(2)-H(2))(Cyttp)]SbF(6) (3), which was shown by X-ray diffraction techniques (space group P&onemacr;, unit cell parameters: a = 9.874(2) Å, b = 14.242(4) Å, c = 16.198(2) Å, alpha = 99.12(2) degrees, beta = 98.85(2) degrees, gamma = 109.42(2) degrees, and Z = 2) to contain a nonclassical polyhydride cation with a triangulated dodecahedral structure in the solid. The same structure is suggested in solution by (1)H NMR data (including T(1) measurements). 3 is inert to loss of H(2) and is unaffected by CO, t-BuNC, and P(OMe)(3) at room temperature. In contrast, 1 reacts with a variety of reagents to afford classical tetrahydride complexes which are thought also to possess a triangulated dodecahedral structure, with the hydrogens in the A sites, from spectroscopic evidence. Accordingly, CS(2), p-O(2)NC(6)H(4)NCS, and EtOC(O)NCS (X=C=S) insert into an Re-H bond to yield ReH(4)(SCH=X)(Cyttp) (5-7, respectively). MeI cleaves one Re-H bond to afford ReH(4)I(Cyttp) (8), and [C(7)H(7)]BF(4) abstracts hydride in the presence of MeCN, t-BuNC, CyNC, or P(OMe)(3) (L) to give [ReH(4)L(Cyttp)]BF(4) (9-12, respectively). A related pentahydride, ReH(5)(ttp) (2, ttp = PhP(CH(2)CH(2)CH(2)PPh(2))(2)), also reacts with HSbF(6) to yield [ReH(6)(ttp)]SbF(6) (4), which appears to be a nonclassical polyhydride in solution by T(1) measurements.

Two derivatives of lithium isodicyclopentadienide: [(1,2,3,3a,7a-eta)-4,5,6,7-tetrahydro-4,7-methanoindenido] (N,N,N1,N1-tetramethylethylenediamine)lithium and Bis (1,4,7,10-tetraoxacyclododecane)-lithium(1+) Bis[(1,2,3,3a,7a-eta)-4,5,6,7-tetrahydro-4,7-methanoindenido]lithate(1- )

Selective crystallization of a solution of lithium isodicyclopentadienide, (isodiCp)Li, in dry thf or diethyl ether under argon has produced two lithium complexes: (isodiCp)Li(TMEDA), [Li(C10H11)(C6H16N2)], (4), and [Li(12-crown-4)2]+. [Li(isodiCp)2]-, [Li(C8H16O4)2]-[Li(C10H11)2], (5). In (4) the Li+ ion is coordinated to the two N atoms of the disordered TMEDA and is eta 5-coordinated to the Cp ring of the isodiCp ligand. The Li-(Cp ring centroid) distance is 1.906 (7) A. In (5) there are two independent half-molecules of the anion and one molecule of the cation in the asymmetric unit. In each anion, the Li+ ion occupies a crystallographic inversion center and is eta 5-coordinated to the two Cp rings of two isodiCp ligands. The Cp rings are in a staggered arrangement, as required by the inversion center. The Li-(Cp ring centroid) distances for the two anions are 1.987 (3) and 2.008 (3) A. In the cation of (5), the Li+ ion is coordinated to two 12-crown-4 ligands, one of which is disordered. Both (4) and (5) exhibit exo coordination of the Li+ ion to the isodiCp ligand, with a resultant slight endo bending of this ligand.

(Z)-5-(2-thienylmethylene)-2,4-imidazolidinedione

The major product formed in the thermolysis of 5-diazouracil in thiophene at 423-433 K has been identified as the unexpected compound (Z)-5-(2-thienylmethylene)-2,4-imidazolidinedione, C8H6N2O2S, by X-ray analysis. The molecule is a hydantoin derivative with a thienylmethylene group substituted at the 5-position. The structure is disordered in that the thiophene ring exists in two orientations which are related by an approximate 180 degree rotation about the C(6)-C(7) bond. All of the N and O atoms are involved in an intermolecular hydrogen-bonding network via N-H...O interactions. This network consists of an infinite chain along the a-axis direction and a cyclic trimer arrangement which branches from this chain. The molecules are arranged in the unit cell in pleated sheets which are approximately perpendicular to the c axis.

Structure of 6-fluoro-1,2,3,4,7,12-hexahydro-7-methyl-12-methylene- benz[a]anthracene

The X-ray analysis confirms the structure of the 12-methylene tautomer formed by the acid catalysis of 6-fluoro-1,2,3,4-tetrahydro-7,12-dimethylbenz[a]anthracene. The central C ring is in a boat conformation, with the result that the molecule is bent about a line through atoms C(7) and C(12) with a dihedral angle of 32.5 degrees. The cyclohexene A ring is in a half-chair conformation.

Structure of dibenzofuran-d8, C12D8O, at 173 K

Crystalline dibenzofuran-d8 has been found to exhibit disorder of the type described previously for dibenzofuran. The disordered molecules are related to the ordered molecules by a 180 degrees rotation about an axis passing through the molecular center of mass and perpendicular to the furan ring. In the present structure 11(2)% of the molecules were found to adopt this alternate orientation. The molecules are bisected by a mirror plane normal to the furan ring and containing the O atom. The average bond length in the benzenoid ring is 1.392 (10) A. The furan ring and the benzenoid ring are separately planar, but form a dihedral angle of 1.45 (9) degrees with each other.

Structure of tetralithium 1,4,5,8-naphthalenetetracarboxylate dodecahydrate

4Li+.C14H4O8(4-).12H2O, M(r) = 544.18, triclinic, P1, a = 9.608 (2), b = 10.034 (2), c = 7.033 (1) A, alpha = 94.29 (1), beta = 96.95 (1), gamma = 64.52 (1) degree, V = 607.4 (2) A3, Z = 1, D chi = 1.49 g cm-3, lambda (Mo K alpha) = 0.71073 A, mu = 1.29 cm-1, T = 295 K, F(000) = 284, R = 0.039 for 2781 unique reflections having I greater than sigma I. The two inequivalent carboxyl groups adopt a non-planar arrangement with respect to the naphthalene core, making dihedral angles of 52.7 (1) and 54.6 (1) degree with it. The Li+ ions are tetrahedrally coordinated by carboxyl and water O atoms. The Li-O distances are in the range 1.906 (3)-2.041 (3) A, averaging 1.97 (4) A; O-Li-O angles are 101.5 (1)-123.9 (1) degree, averaging 109 (6) degrees. Each of the 12 inequivalent water H atoms is involved in hydrogen bonding. Of these bonds, 11 are typical two-centered hydrogen bonds with an average H...O (acceptor) distance of 1.92 (11) A and an average O-H...O (acceptor) angle of 172 (5) degrees. One water H atom is involved in a three-centered hydrogen bond with an average H...O (acceptor) distance of 2.61 (4) A and an average O-H...O (acceptor) angle of 120 (3) degrees. Adjacent organic anions are separated by the Li+ ions and their coordination polyhedra, with the water molecules occupying positions above and below the naphthalene rings and participating in a three-dimensional hydrogen-bonded network.

Modulation of carcinogenicity in 1,2,3,4-tetrahydro-7,12- dimethylbenz[a]anthracene (THDMBA) by fluorine substitution: crystal structures of the 5- and 6-fluoro regioisomers

1,2,3,4-Tetrahydro-7,12-dimethylbenz[a]anthracene (THDMBA) is an animal carcinogen which lacks an aromatic bay-region and shows promise as a model to investigate non-classical mechanisms of carcinogenesis. The fluorine-substituted derivatives at positions 5 and 6 on the B-ring exhibit a striking range of oncogenic potential wherein the 6F-THDMBA is twice as potent as the parent carcinogen, but the 5F-THDMBA is virtually inactive. To study structure-reactivity relationships for these fluorine regioisomers, we have determined the three-dimensional structures of the compounds by single-crystal X-ray diffraction. These crystal structures are the first such to be reported for any monofluoro anthracene (or pyrene) derivative. The partially-reduced A-ring exists in both enantiomeric half-chair conformers in the crystalline state, and the compounds have quasi-planar anthracene ring systems which exhibit a right-handed twist in the 'beta'-conformer, with the expected opposite twist in the other. A complete analysis of bond lengths, bond angles and torsion angles is presented. Preliminary electrostatic potentials have been derived from the X-ray data sets, and the results indicate significant differences in potential between 5F- and 6F-THDMBA at positions near the partially reduced bay region. Such results are likely to be of importance in the understanding of metabolic activation to reactive intermediates capable of bonding covalently to DNA.

The structure of hexaaquaaluminium(III) bromate trihydrate, [Al(H2O)6](BrO3)3.3H2O

Hexaaquaaluminium(III) bromate trihydrate, [Al(H2O)6](BrO3)3.3H2O, M(r) = 572.84, triclinic, P1, a = 9.536 (2), b = 11.095 (4), c = 9.291 (2) A, alpha = 106.58 (2), beta = 100.42 (2), gamma = 113.01 (2) degrees, V = 818.1 (4) A3, Z = 2, Dx = 2.33 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 74.58 cm-1, F(000) = 560, T = 296 K, R = 0.050 for 3777 unique reflections having I greater than sigma 1. The single type of Al ion is coordinated by six inequivalent water O atoms which form a slightly distorted octahedron. The average Al--O distance within the octahedron is 1.872 (11) A. Each of the three inequivalent bromate groups has three inequivalent O atoms. The average Br--O distances and O--Br--O angles for these ions are: 1.652 (25) A and 104.1 (17) degrees for Br(1)O3; 1.650 (9) A and 104.4 (18) degrees for Br(2)O3; 1.643 (9) A and 103.6 (14) degrees for Br(3)O3. The aluminium-oxygen complex conformed to rigid-body behavior but the bromate groups did not. Corrected for rigid-body motion, the average Al--O distance becomes 1.880 (10) A. Least-squares refinement of the positional parameters of the 18 inequivalent H atoms permitted a detailed analysis of the hydrogen bonding.

1,2-Naphthalenedicarboxylic acid: structures of channel clathrates and an unsolvated crystalline phase

(1) 1,2-Naphthalenedicarboxylic acid-diethyl ether, C12H8O4.nC4H10O, M(r) = 216.19, tetragonal, I4(1)/a, a = 22.086 (3), c = 9.463 (3) A, V = 4616 (2) A3, Z = 16, F(000) = 1792 (without ether), F(000) = 1873 (with 2.7 molecules of ether per unit cell), Dx = 1.24 g cm-3 (without ether), Dx = 1.31 g cm-3 (with 2.7 molecules of ether per unit cell), lambda(Mo K alpha) = 0.71073 A, T = 296 K, mu = 0.88 cm-1, R = 0.052 for 1130 unique reflections having I greater than 3 sigma I. (2) 1,2-Naphthalenedicarboxylic acid, C12H8O4, M(r) = 216.19, triclinic, P1, a = 9.027 (1), b = 9.234 (1), c = 7.256 (1) A, alpha = 106.08 (1), beta = 90.79 (1), gamma = 111.80 (1) degrees, V = 535.0 (1) A3, Z = 2, F(000) = 224, Dx = 1.34 g cm-3, lambda (Mo K alpha) = 0.71073 A, T = 296 K, mu = 0.95 cm-1, R = 0.043 for 1216 unique reflections having I greater than 3 sigma I. (3) 1,2-Naphthalenedicarboxylic acid-dimethoxyethane, C12H8O4.nC4H10O2, M(r) = 216.19, tetragonal, I4(1)/a, a = 22.067 (2), c = 9.465 (2) A, V = 4609 (1) A3, Z = 16, Dx = 1.25 g cm-3 (without dimethoxyethane), Dx = 1.39 g cm-3 (with 4.4 molecules of dimethoxyethane per unit cell), lambda(Mo K alpha) = 0.71073 A, T = 296 K.(ABSTRACT TRUNCATED AT 250 WORDS)

Structure of the sodium salt of 1,4,5,8-naphthalenetetracarboxylic acid 4,5-anhydride hydrate

Sodium hydrogen 1,3-dioxo-1H,3H-naphtho[1,8-cd]pyran-6,7-dicarboxylate hydrate, Na[C14H5O7].H2O, Mr = 326.2, triclinic, P1, a = 9.520 (2), b = 9.549 (3), c = 7.860 (1) A, alpha = 105.88 (2), beta = 110.29 (1), gamma = 100.89 (2) degrees, V = 611.9 (3) A3, Z = 2, Dx = 1.77 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 1.67 cm-1, F(000) = 332, T = 295 K, R = 0.042 for 1665 unique reflections having I greater than 3 sigma I. The organic portion of this structure demonstrates near-C2 symmetry with a pseudo-twofold axis coincident with the central C-C naphthalene ring bond. The atoms of the naphthopyran three-ring system deviate by an average of 0.037 (19) A from the best least-squares plane through the three rings. Each of the carboxyl group planes is substantially inclined to the naphthopyran ring plane, the average dihedral angle measuring 62 (1) degree. The Na ion is coordinated by O atoms in a highly distorted octahedral geometry with a mean Na--O distance of 2.49 (12) A. A short hydrogen bond is formed between a carboxylic acid group and a carboxylate anion; the H...O(acceptor) distance is 1.35 (5) A and the O...O(acceptor) distance is 2.475 (3) A. The acid H-atom position is located asymmetrically with respect to the O atoms. The water H atoms are involved in unequal three-centered hydrogen bonds. The molecules are stacked such that the naphthopyran ring portion of the structure is nearly parallel to the ab cell face and the stacks are connected by the hydrogen bonds.(ABSTRACT TRUNCATED AT 250 WORDS)

Structure of sodium perbromate monohydrate

NaBrO4.H2O, Mr = 184.90, monoclinic, C2/c, a = 15.7575 (19), b = 5.7373 (15), c = 11.3390 (19) A, beta = 111.193 (10)degrees, V = 955.8 (3) A3, Z = 8, Dx = 2.570 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 85.2 cm-1, F(000) = 704, T = 296 K, R = 0.039 for 1137 unique reflections having I greater than sigma I. In this structure, there are two inequivalent Na ions, each coordinated by six O atoms. In each of the two types of distorted octahedra, there are three inequivalent Na--O distances; the average Na(1)--O and Na(2)--O distances are 2.379 (10) and 2.405 (23) A, respectively. The perbromate ion in this structure displays very nearly regular tetrahedral geometry, although it is subject to no symmetry constraints; the average observed Br--O distance is 1.601 (4) A, while the average observed O--Br--O angle is 109.5 (9)degrees. These values agree well with previously reported values. The perbromate ion, but neither of the sodium coordination polyhedra, shows rigid-body behavior. The average rigid-body corrected Br--O distance in the perbromate ion is 1.624 (3) A. Refinement of the two inequivalent H atoms permitted detailed analysis of the hydrogen bonding, which is slightly different from that reported for the isomorphic sodium perchlorate monohydrate. Dynamic disordering of the H atoms as detailed by magnetic resonance methods for sodium perchlorate monohydrate is not clearly indicated in our X-ray study of sodium perbromate monohydrate.

Structure of tetrasodium 1,4,5,8-naphthalenetetracarboxylate octahydrate

Na4[C14H4O8].8H2O, Mr = 536.3, monoclinic, P2(1)/n, a = 6.142 (1), b = 8.144 (3), c = 20.527 (4) A, beta = 93.97 (1) degrees, V = 1024.4 (5) A3, Z = 2, Dx = 1.74 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 2.14 cm-1, F(000) = 552 T = 295 K, R = 0.039 for 1769 unique reflections having I greater than sigma I. In this structure, the title compound has an inversion center at the midpoint of the central naphthalene ring bond. The average C-C bond length in the naphthalene core is 1.41 (3) A; the average interior angle is 119.9 (1.0) degrees. The exterior angle at the central naphthalene carbon is 122.7 (3) degrees, significantly smaller than in 1.8-substituted naphthalenes. The two inequivalent carboxyl groups adopt a non-planar arrangement with respect to the naphthalene core, making an average dihedral angle of 53.8 (1) degree with it. The two inequivalent sodium ions have quite different environments. Na(1) is coordinated by six O atoms in a highly distorted octahedral arrangement with an average Na-O distance of 2.44 (10) A. Na(2) is coordinated by five O atoms in a highly distorted trigonal bipyramidal arrangement with an average Na-O distance of 2.36 (3) A. Each of the eight inequivalent water H atoms is involved in a single hydrogen bond. The average H...O (acceptor) distance is 2.00 (5) A, the average O...O (acceptor) distance is 2.85 (5) A and the average O-H...O (acceptor) angle is 165 (8) degrees for these hydrogen bonds.(ABSTRACT TRUNCATED AT 250 WORDS)

Structure of hexaaquacopper(II) bromate

[Cu(H2O)6](BrO3)2, Mr = 427.44, cubic, Pa3, a = 10.3240 (6) A, V = 1100.38 (4) A3, Z = 4, Dx = 2.580 g cm-3, lambda (Mo K alpha) = 0.71073 A, mu = 92.32 cm-1, F(000) = 828, T = 296 K, R = 0.038 for 336 unique reflections having I greater than sigma I. The single type of copper ion (site symmetry 3) is coordinated by six water-molecule O atoms, each at an observed distance of 2.079 (4) A, in an array which is virtually regular octahedral, the nominal 90 degree angles measuring 89.95 (15) and 90.05 (15) degrees. Thus, this is not a typical CuII complex in which (consistent with a static Jahn-Teller effect) a distorted octahedral array displays '(2 + 2 + 2)' coordination; rather, it is the sixth strict example of a CuII static structure inconsistent with the Jahn-Teller theorem. The presence of a dynamic Jahn-Teller effect is supported by the data. The single type of bromate ion has an observed Br-O bond length 1.649 (3) A and O-Br-O bond angle 104.17 (15) degrees. The bromate ion was found to manifest rigid-body behavior but, consistent with a dynamic Jahn-Teller effect, the copper-oxygen complex did not. The Br-O bond length corrected for rigid-body motion is 1.663 A. Refinement of the positional parameters of the two inequivalent H atoms permitted a detailed analysis of hydrogen bonding, which occurs principally between the oxygen octahedra and the bromate groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Structure of 4-dibenzofurancarboxaldehyde, C13H8O2

Mr = 196.21, monoclinic, P2(1)/n, a = 6.589 (1), b = 9.784 (2), c = 14.394 (2) A, beta = 95.69 (1) degrees, V = 923.4 (3) A3, Z = 4, Dx = 1.41 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 0.89 cm-1, F(000) = 408, T = 296 K, R = 0.048 for 964 unique reflections having I greater than 3 sigma I. The average C-C bond length within the benzenoid rings in 4-dibenzofurancarboxaldehyde is 1.388 (9) A; the average interior angle is 120.0 (2.6) degrees. While two of the three rings of 4-dibenzofurancarboxaldehyde are planar, the benzenoid ring to which the carbonyl group is attached is slightly non-planar. The dihedral angle between the two benzenoid rings measures 1.4(1) degrees. The structure is composed of pairs of 4-dibenzofurancarboxaldehyde molecules related by inversion centers. This structure is further characterized by approaches of both the carbonyl and the furan O atoms to ring H atoms with separations which are slightly less than the sum of the relevant van der Waals radii.

Structure of 1,8-naphthalenedicarboxylic acid (naphthalic acid), C12H8O4: ring geometry and hydrogen-bonding effects

C12H8O4, Mr = 216.19, orthorhombic, Pbca, a = 15.308 (2), b = 17.926 (2), c = 7.093 (2) A, V = 1946.4 (5) A3, Z = 8, Dx = 1.48 g cm-3, lambda (Mo K alpha) = 0.71073 A, mu = 1.05 cm-1, F(000) = 896, T = 296 K, R = 0.043 for 912 unique reflections having I greater than 3 sigma (I). In this structure, 1,8-naphthalenedicarboxylic acid departs significantly from planarity. While the average deviation of carbons from the best least-squares plane for the naphthalene core is 0.055 (4) A, the carboxyl carbons adopt positions +0.403 (4) and -0.350 (4) A from that plane. The carboxyl groups are twisted in the same direction with respect to that plane and make an average dihedral angle of 42.6 (3) degrees with it. The nearly equal lengths of the C--O distances within the carboxyl groups [mean value 1.267 (5) A] indicate almost complete disorder of the H atoms of these groups. Hydrogen bonding occurs in cyclic dimer fashion between two molecules related by a center of inversion. The carboxyl hydrogens appear to be subject to a symmetric double-minimum potential and to be disordered via tunneling; there is no evidence that the carboxyl oxygens are disordered. The mean carboxyl H--O acceptor distance is 1.90 (7) A.

Structure of hexaaquanickel(II) bromate

[Ni(H2O)6](BrO3)2, Mr = 422.60, cubic, Pa3, a = 10.2987 (6) A, V = 1092.3 (2) A3, Z = 4, F(000) = 824, Dx = 2.57 g cm-3, lambda(Mo K alpha) = 0.71073 A, mu = 90.79 cm-1, T = 296 K, R = 0.024 for 360 unique reflections having I greater than sigma I. The single type of nickel ion is coordinated by six water-molecule O atoms, each at an observed distance of 2.061 (2) A, in an almost regular octahedral array. The single type of bromate ion has an observed Br--O bond length of 1.655 (2) A and O--Br--O bond angle 104.25 (9) degrees. Both the nickel-oxygen complex and the bromate ion were found to manifest rigid-body behavior. The Ni--O distance corrected for rigid-body motion is 2.065 A, while the corrected Br--O bond length is 1.663 A. Location and refinement of the two inequivalent H atoms permitted a detailed analysis of the hydrogen bonding, which occurs principally between the oxygen octahedron and the bromate groups. This structure is isomorphic to the structures of hexaaquanickel(II) chlorate and hexaaquacobalt(II) bromate which have been reported recently from this laboratory.

Structure of diethyl 1,2,3,3b,4a,5,6,7,8,8a,8b,9-dodecahydro-1,5-dioxo-4,8,9-metheno-4H-cycl openta [1,2-a:4,3-a']dipentalene-4,10-dicarboxylate

C24H24O6, Mr = 408.45, triclinic, P1, a = 10.276 (2), b = 13.000 (2), c = 7.782 (1) A, alpha = 98.06 (1), beta = 97.63 (1), gamma = 84.43 (1) degree, V = 1017 A3, Z = 2, Dx = 1.33 g cm-3, lambda(Mo K alpha) = 0.71069 A, mu = 0.89 cm-1, F(000) = 432, T = 296 K, R = 0.048 for 3321 unique reflections with Fo2 greater than 3 sigma(Fo2). Both cyclopentenones are canted in the endo direction (6.0 and 7.9 degrees), the one syn to the ethoxy groups less so for steric reasons. When the ester groups are disregarded, the polyquinane portion of the molecule is seen to possess a non-crystallographic twofold axis. The overall molecular geometry is reconcilable with the absence of any significant alteration in the density maximum of the C--C pi bonds at this level of downward pyramidalization.

Structure of tetraaquacopper(II) chlorate at 296 and 223 K

[Cu(H2O)4](ClO3)2, Mr = 302.51, orthorhombic, Pbca, lambda (Mo K alpha) = 0.71069 A, Z = 4, F(000) = 604; T = 296 K, a = 12.924 (3), b = 9.502 (2), c = 7.233 (1) A, V = 888.3 (3) A3, D chi = 2.26 g cm-3, mu = 31.04 cm-1, R = 0.041 for 1174 unique reflections with I greater than sigma (I); T = 223 K, a = 12.853 (2), b = 9.492 (2), c = 7.216 (2) A, V = 880.4 (3) A3, D chi = 2.28 g cm-3, mu = 31.28 cm-1, R = 0.033 for 1279 unique reflections with I greater than sigma (I). The single type of copper ion is octahedrally coordinated by four water oxygens and two chlorate ion oxygens; the complex is characterized by three distinct pairs of Cu-O distances (which we have previously described as '2 + 2 + 2' coordination), one of which is substantially larger than the remaining two. The nominal 90 degrees O-Cu-O angles of the complex differ from that value by at most +/- 1.8 degrees. The observed structure of the complex is typical for copper(II) and is consistent with the Jahn-Teller effect. The single type of chlorate ion shows the expected trigonal pyramidal geometry, with average Cl-O bond lengths 1.485 (13) and 1.490 (11) A and average O-Cl-O bond angles 106.8 (13) and 106.8 (13) degrees for 296 and 223 K, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Structure of tetraaquacobalt(II) bromide dihydrate (cobalt bromide hexahydrate)

Tetraaquacobalt(II) bromide dihydrate, [Co(H2O)4]Br2 x 2H2O, Mr = 326.83, monoclinic, C2/m, a = 11.0158(12), b = 7.1694(10), c = 6.9111(10) A, beta = 124.761(7)degrees, V = 448.4(1) A3, Z = 2, F(000) = 314, Dx = 2.420 g cm-3, lambda(Mo K alpha) = 0.71069 A, T = 296 K, mu = 107.13 cm-1, R = 0.022 for 532 unique reflections having I greater than 0. The single type of Co ion is octahedrally coordinated by four equivalent water-molecule O atoms at the observed distance 2.081(2) A and two equivalent Br ions at the observed distance 2.6048(5) A in an array which, with respect to its angles, departs only slightly from regular octahedral geometry. The cobalt-oxygen-bromine complex was found to manifest rigid-body behavior. The cobalt-oxygen distance corrected for rigid-body motion was found to be 2.088 A; the corrected cobalt-bromine distance, 2.6081 A. Associated with each complex are two water molecules of hydration. Assignment and refinement of the coordinates of the four non-equivalent H atoms permitted detailed analysis of the hydrogen bonding, which involves each of the four non-equivalent H atoms significantly. The structure as determined in this study differs markedly from that presented in the sole published single-crystal study [Stroganov, Andreev, Kozina & Solov'ev (1961). Vestn. Leningr. Univ. Ser. Mat. Fiz. Khim. 16, 114-119]. In particular, the space-group assignment differs and the pattern of bromine-oxygen distances is quite different. Contrary to Stroganov et al., this structure is isomorphic with that of cobalt chloride hexahydrate.

Structure of phenoxathiin (phenothioxin), C12H8OS, at 223 K

Mr = 200.25, orthorhombic, P2(1)2(1)2(1), a = 7.758(2), b = 20.506(3), c = 5.896(2) A, V = 938.0(4) A3, Z = 4, Dx = 1.42 g cm-3, lambda(Mo K alpha) = 0.71069 A, mu = 2.88 cm-1, F(000) = 416, T = 223 K, R = 0.044 for 1414 unique reflections having I greater than 3 sigma I. The phenoxathiin molecule is constituted of two very nearly regular planar hexagonal carbocyclic (benzenoid) rings joined to a non-planar heterocyclic ring. The heterocyclic ring geometry is described in terms of two intersecting planes between which the dihedral angle, the molecular fold angle, is 142.3 degrees. The angle at S (C-S-C) is 97.7(1) degrees, while the angle at O (C-O-C) is 117.4(2) degrees. The overall mean C-C distance in the carbocyclic rings is 1.387(7) A. The absence in this structure of the type of disorder previously found in the dibenzofuran structure is readily understandable since eight sets of close approaches involving each molecule were found in the present structure. These close approaches involve S and O atoms as well as H atoms.

Structure of hexaaquacobalt(II) bromate

[Co(H2O)6](BrO3)2, Mr = 422.83, cubic, Pa-3, a = 10.3505 (7) A, V = 1108.88 (8) A3, Z = 4, Dx = 2.53 g cm-3, lambda(Mo K-alpha) = 0.71069 A, mu = 87.31 cm-1, F(000) = 820, T = 296 K, R = 0.027 for 365 unique reflections having I greater than sigma I. The single type of Co ion is coordinated by six water-molecule O atoms, each at an observed distance 2.095 (2) A, in an array which is regular octahedral within the estimated standard deviations of the relevant angles. The single type of bromate ion has a Br-O bond length 1.653 (2) A and O-Br-O bond angle 104.07 (9) degrees. The cobalt-oxygen complex manifested rigid-body behavior, but the bromate ion did not. The cobalt-oxygen distance corrected for rigid-body motion is 2.099 A. Location and refinement of the two inequivalent H atoms permitted detailed analysis of the hydrogen bonding, which occurs principally between the oxygen octahedra and the bromate groups. This structure is isomorphic to that of hexa-aquanickel(II) chlorate recently reported from this laboratory.

Structure of nickel(II) perbromate hexahydrate at 296 K

Ni(BrO4)2.6H2O, Mr = 454.61, trigonal, P3, a = 7.874 (1), c = 5.423 (2) A, V = 291.2 (1) A3, Z = 1, D chi = 2.59 g cm-3, lambda(Mo K alpha) = 0.71069 A, mu = 85.36 cm-1, F(000) = 222, T = 296 K, R = 0.029 for 457 unique reflections having I greater than 0. The room-temperature structure is very similar to that reported previously for a sample at 169 K. The water O atoms form a very slightly distorted octahedron about nickel while the perbromate-ion geometry is virtually regular tetrahedral. Both the coordination polyhedron and the perbromate ion were tested and found to behave as rigid bodies. Corrected for rigid-body motion, the Ni--O(2) distance is 2.064 (2) A and the mean Br--O distance in the perbromate ion is 1.629 (3) A. A detailed account of the hydrogen bonding is presented. The structure previously determined at 169 K is most probably not the stable structure at that temperature.

The structure of hexaaquanickel(II) chlorate

Hexaaquanickel(II) chlorate, [Ni(H2O)6]-(ClO3)2, Mr = 333.69, cubic, Pa3-, a = 10.3159 (5) A, V = 1097.80 (5) A3, Z = 4, F(000) = 680, Dx = 2.02 g cm-3, lambda(Mo K alpha-) = 0.71069 A, T = 296 K, mu = 23.13 cm-1, R = 0.026 for 388 unique reflections having I greater than sigma I. The single type of Ni ion is coordinated by six water-molecule O atoms, each at an observed distance 2.054 (1) A, in an almost regular octahedral array. The single type of chlorate ion has a Cl--O bond length 1.487 (1) A and O--Cl--O bond angle 106.45 (6) degrees. The Ni--O complex, but not the chlorate ion, manifested rigid-body behavior. The Ni--O distance corrected for rigid-body motion is 2.060 A. Location and refinement of the two inequivalent H atoms permitted a detailed analysis of hydrogen bonding, which occurs principally between the oxygen octahedra and the chlorate groups.

Structure of copper(II) perchlorate hexahydrate

Cu(ClO4)2.6H2O, Mr = 370.54, monoclinic, P2(1)/c, a = 5.137 (1), b = 22.991 (3), c = 13.849 (2) A, beta = 90.66 (1) degree, V = 1635.4 (4) A3, Z = 6, Dx = 2.26 g cm-3, lambda(Mo K alpha) = 0.71069 A, mu = 26.44 cm-1, T = 296 K, F(000) = 1122, 2911 unique reflections having I greater than sigma 1, R = 0.030. Each of the two inequivalent copper ions is coordinated by six water-molecule O atoms in a significantly distorted octahedral arrangement. Each of the three inequivalent but geometrically quite similar perchlorate groups is slightly distorted from regular tetrahedral geometry. The overall observed mean Cl-O distance is 1.429 (5) A while the overall observed mean perchlorate O-O distance is 2.333 (8) A. Both the Cu-O complexes and the perchlorate ions were tested and found to behave as rigid bodies. The perchlorate-ion parameters corrected for rigid-body motion are: overall mean Cl-O distance, 1.453 (6) A; overall mean perchlorate O-O distance, 2.372 (8) A. Location and refinement of the 18 H atoms gave a detailed account of hydrogen bonding, which occurs between oxygen octahedra, between oxygen octahedra and perchlorate groups, and, more weakly, within oxygen octahedra.

X-ray crystallographic analysis of the structural distortions induced by substitution and annulation of the dodecahedrane nucleus

Methyl dodecahedranecarboxylate, C22H22-O2, (4), Mr = 318.42, monoclinic, C2/c, a = 12.600 (2), b = 7.992 (4), c = 28.975 (7) A, beta = 101.79 (2) degrees, V = 2856 A3, Z = 8, Dx = 1.48 g cm-3, lambda(Mo K-alpha) = 0.71073 A, mu = 0.84 cm-1, F(000) = 1360, T = 294 K, R = 0.044 for 2109 unique reflections with Fo2 greater than 3 sigma(Fo2). 21-Phenylcyclopropadodecahedrane, C27H24, (5), Mr = 348.49, tetragonal, P4(2)/n, a = 17.528 (3), c = 10.752 (2) A, V = 3303 A3, Z = 8, Dx = 1.40 g cm-3, lambda(Mo K-alpha) = 0.71069 A, mu = 0.85 cm-1, F(000) = 1488, T = 295 K, R = 0.053 for the 1773 unique reflections with Fo2 greater than 1 sigma(Fo2). The molecular geometries of methoxycarbonyldodecahedrane (4) and 21-phenylcyclopropadodecahedrane (5) are compared to those of the parent C20H20 hydrocarbon (1) and its 1,16-dimethyl derivative (2). For both (2) and (4), the framework is modestly distorted by the substituents, the intracavity distance being more extended along the axis that contains the pendant group(s). Remarkably for (5), its cyclopropane ring has all C-C bonds and internal angles essentially equal, and those dodecahedrane bonds in the immediate vicinity of the ring fusion are extensively perturbed.

Synthesis and P-388 antitumor properties of the four diastereomeric 1-hydroxy-3,4-diaminocyclohexane-Cl2PtII complexes

Synthesis and antileukemic activity in vivo of the four diastereomeric 1-hydroxy-3,4-diaminocyclohexane-Cl2PtII complexes (Cl2PtII-3a-d) are described. Respective bis(phenylmethyl) (1 alpha,2 alpha,4 beta)-, (1 alpha,2 alpha,4 alpha)-, (1 alpha,2 beta,4 beta)-, and (1 alpha,2 beta,4 alpha)-(4-hydroxy-1,2-cyclohexanediyl)bis(carbamates) (5a, 5b, 7a, 7b) were prepared by hydroboration-oxidation of the bis(carbobenzoxyamino) derivatives (4,5) of cis- and trans-4,5-diaminocyclohexene. The relative stereochemistry of intermediates 5a and 5b was established by correlation with the alcohol obtained by NaBH4 reduction of bis(phenylmethyl) (1 alpha,2 alpha,3 alpha,4 alpha)-(3,4-epoxy-1,2-cyclohexanediyl)bis(carbamate) (8), the all-cis stereochemistry of which was unambiguously determined by X-ray crystallographic analysis. In the P-388 murine leukemia model these monohydroxycyclohexanediamine-PtII complexes were more effective than the PtII complexes of the related diol diamines 1a-e but were less active than the cisplatin positive control.

Structure of barium perchlorate trihydrate

Ba(ClO4)2.3H2O, Mr = 390.28, hexagonal, P63/m, a = 7.277 (2), c = 9.656 (1) A, V = 442.9 (1) A3, Z = 2, F(000) = 368, D chi = 2.93 g cm3, lambda(Mo K alpha) = 0.71069 A, T = 295 K, mu = 52.60 cm1, 456 unique reflections, R = 0.023. The barium atoms in this structure are coordinated by six water oxygens, O(3), at 2.919 (1) A and by six perchlorate oxygens, O(2), at 3.026 (2) A in a slightly distorted icosahedral arrangement, the average Ba-O separation thus being approximately 2.97 A. The perchlorate ion just fails to have regular tetrahedral geometry within the experimental error, and has an average Cl-O bond length of 1.433 (6) A. Consistent with hydrogen bonding delineated on the basis of least-squares-refined hydrogen-atom positions, each axial [O(1)] perchlorate oxygen is hydrogen bonded to three water molecules and each trigonal [O(2)] perchlorate oxygen is hydrogen bonded to two water molecules; thus each perchlorate ion is hydrogen bonded to nine water molecules. Conversely, each water molecule [O(3)] oxygen is hydrogen bonded to six perchlorate ions to two through axial [O(1)] oxygens and to four through trigonal [O(2)] oxygens.

The crystal and molecular structure of syn-[4.4.3]propella-2,4,12-trien-11-ol 3,5-dinitrobenzoate

The crystal structure of syn-[4.4.3]propella-2,4,12-trien-11-ol 3,5-dinitrobenzoate, 2, has been determined by single crystal X-ray diffraction and refined to an R value of 0.051. The crystal structure is triclinic with a = 10.208(2), b = 13.355(2), c = 7.068(1) Å, α = 99.35(1)°, β = 100.63(1)°, γ = 100.79(1)°, and the space group is [Formula: see text] with two molecules per cell, D(calcd) = 1.39 g cm−3. The unsaturated five-membered ring resides in an envelope conformation with C6—C11—C12—C13 lying essentially in a plane. The fifth atom, C1, is positioned 0.47 Å out of this plane on the side opposite O1. The latter is situated 1.38 Å away and projects the 3,5-dinitrobenzoate group above the central portion of the cyclohexadiene unit. Four contiguous carbon atoms in the latter ring are mutually coplanar and the fused cyclohexane ring adopts a chair conformation. The overall molecular geometry is reconcilable with its solvolytic behavior in aqueous acetone.

Optically active catecholimidazolines: a study of steric interactions at alpha-adrenoreceptors

The optical isomers and deoxy form of 2-(3,4, alpha-trihydroxybenzyl)imidazoline hydrochloride were examined for their alpha-adrenergic activity on rat aorta. The rank order of stimulant activity was deoxy (2) congruent to (R)-(-)-1 greater than (S)-(+)-1. This is in contrast to catecholamines in which the order of activity is (R)-(-)-epinephrine greater than (S)-(+)-epinephrine = epinine (deoxyepinephrine). The relative order of potency for the isomers of 2-(3,4, alpha-trihydroxybenzyl)imidazoline is different than that predicted by the Easson--Stedman theory for stereoisomers of catecholamines. Also, substitution of the deoxy compound 2 with substituents, methyl or benzyl, in the 4-position lowers the alpha-adrenergic agonist activity, and differences observed between optical isomers were small.