Crystal structure and coordination chemistry of the pentane-soluble sodium salt of an oxygen tripod ligand

Tin(II) and Tin(IV) Complexes Incorporating the Oxygen Tripodal Ligands [(η5-C5R5)Co{P(OEt)2O}3]-, (R = H, Me; Et = -C2H5) as Potent Inflammatory Mediator Inhibitors: Cytotoxic Properties and Biological Activities against the Platelet-Activating Factor (PAF) and Thrombin

Metal complexes displaying antiplatelet properties is a promising research area. In our methodology, Platelet-Activating Factor (PAF), the most potent lipid pro-inflammatory mediator, serves as a biological probe. The antiplatelet activity is exerted by the inhibition of the PAF-induced aggregation in washed rabbit platelets (WRPs) and in rabbit plasma rich in platelets (rPRPs). Herein, the synthesis and biological investigation of a series of organometallic tin(II) and tin(IV) complexes, featuring the oxygen tripodal Kläui ligands [(η⁵-C₅R₅)Co{P(OEt)₂O}₃]^-, {R = H, (L_OEt^-); Me (L*_OEt^-)}, are reported. Reaction of NaL_OEt (1a) and NaL*_OEt (1b) with SnCl₂, yielded the rare four-coordinate L_OEtSnCl (2a) and L*_OEtSnCl (2b) complexes. Accordingly, L_OEtSnPh₃ (3a) and L*_OEtSnPh₃ (3b) were prepared, starting from Ph₃SnCl. Characterization includes spectroscopy and X-ray diffraction studies for 2a, 2b and 3b. The antiplatelet activity of the lead complexes 2b and 3a (IC₅₀ = 0.5 μΜ) is superior compared to that of 1a and 1b, while both complexes display a pronounced inhibitory activity against thrombin (IC₅₀ = 1.8 μM and 0.6 μM). The in vitro cytotoxic activities of 3a and 2b on human Jurkat T lymphoblastic tumor cell line is higher than that of cisplatin.

Thiacalix[4]arene-supported mononuclear lanthanide compounds: slow magnetic relaxation in dysprosium and erbium analogues

Four mononuclear Ln^III compounds have been synthesized, and the dysprosium and erbium analogues exhibit typical field-induced SMM behavior.

Syntheses, structures, and magnetic properties of homodinuclear lanthanide complexes based on dinucleating Schiff base ligands

Two series of homodinuclear lanthanide(iii) complexes were synthesized and characterized. Magnetic studies reveal the weakly antiferromagnetic coupling between paramagnetic Ln ions and enhanced relaxation of magnetization for Dy₂ complexes.

Syntheses, structures, and magnetic properties of seven-coordinate lanthanide porphyrinate or phthalocyaninate complexes with Kläui's tripodal ligand

A series of seven-coordinate mononuclear lanthanide(III) complexes of the general formula [(TPP)Ln(L(OEt))]·0.25H2O and [(Pc)Ln(L(OEt))] (Ln(3+) = Dy(3+), Tb(3+), Ho(3+), and Gd(3+); TPP = 5,10,15,20-tetraphenylporphyrinate; Pc = phthalocyaninate; L(OEt)(-) = [(η(5)-C5H5)Co(P(=O)(OEt)2)3](-)) are synthesized on the basis of the tripodal ligand L(OEt)(-) and either porphyrin or phthalocyanine ligands. All of the complexes are characterized by X-ray crystallography and by static and dynamic magnetic measurements. The Dy and Tb complexes show the field-induced slow relaxation of magnetization, and they are interesting seven-coordinate single-lanthanide-based SMMs. The magnetic relaxation properties of these double-decker sandwich complexes are influenced by the local molecular symmetry and are sensitive to subtle distortions of the coordination geometry of the paramagnetic lanthanide ions, such as metal-to-plane distances, plane center distances, and bending angles.

Syntheses, structures, and magnetic properties of low-dimensional heterometallic complexes based on the versatile building block [(Tp)Cr(CN)3]-

Using the tricyano precursor (Bu(4)N)[(Tp)Cr(CN)(3)] (Bu(4)N(+) = tetrabutylammonium cation; Tp = tris(pyrazolyl)hydroborate), a pentanuclear heterometallic cluster [(Tp)(2)Cr(2)(CN)(6)Cu(3)(Me(3)tacn)(3)][(Tp)Cr(CN)(3)](ClO(4))(3)·5H(2)O (1, Me(3)tacn = N,N',N'-trimethyl-1,4,7-triazacyclononane), three tetranuclear heterometallic clusters [(Tp)(2)Cr(2)(CN)(6)Cu(2)(L(OEt))(2)]·2.5CH(3)CN (2, L(OEt) = [(Cp)Co(P(O)(OEt)(2))(3)], Cp = cyclopentadiene), [(Tp)(2)Cr(2)(CN)(6)Mn(2)(L(OEt))(2)]·4H(2)O (3), and [(Tp)(2)Cr(2)(CN)(6)Mn(2)(phen)(4)](ClO(4))(2) (4, phen = phenanthroline), and a one-dimensional (1D) chain polymer [(Tp)(2)Cr(2)(CN)(6)Mn(bpy)](n) (5, bpy = 2,2'-bipyridine) have been synthesized and structurally characterized. Complex 1 shows a trigonal bipyramidal geometry in which [(Tp)Cr(CN)(3)](-) units occupy the apical positions and are linked through cyanide to [Cu(Me(3)tacn)](2+) units situated in the equatorial plane. Complexes 2-4 show similar square structures, where Cr(III) and M(II) (M = Cu(II) or Mn(II)) ions are alternatively located on the rectangle corners. Complex 5 consists of a 4,2-ribbon-like bimetallic chain. Ferromagnetic interactions between Cr(III) and Cu(II) ions bridged by cyanides are observed in complexes 1 and 2. Antiferromagnetic interactions are presented between Cr(III) and Mn(II) ions bridged by cyanides in complexes 3-5. Complex 5 shows metamagnetic behavior with a critical field of about 22.5 kOe at 1.8 K.

Bis{[(η)-cyclopentadienyl]tris(diethyl phosphito-κP,P',P'')cobaltate(III)-κO,O',O'']oxovanadium(IV)}-μ-oxalate

The title compound {systematic name: bis[1,4(η⁵)-cyclo­penta­dien­yl]hexa­kis(μ-diethyl phosphito)-1:2κ⁶P:O;3:4κ⁶O:P-μ-ox­alato-2:3κ⁴O¹,O²:O^1′,O^2′-dioxido-2κO,3κO-1,4-dicobalt(III)-2,3-divanadium(IV)}, [Co₂V₂(C₅H₅)₂(C₂O₄)(C₄H₁₀O₃P)₆O₂], is an oxalate-bridged dinuclear complex of oxovanadium(IV). The geometric center of the dimer lies on an inversion center. The unique Co atom is bonded to three P atoms and a cyclo­penta­dienyl ring. The unique V atom has six O atom neighbors in an approximately octa­hedral arrangement; the V—O bond trans to the V=O bond is significantly lengthened.

Poly[μ(3)-aqua-μ(2)-2,4-dinitro-phenolato-rubidium(I)]

The asymmetric unit of the title compound, [Rb(C₆H₃N₂O₅)(H₂O)]_n, comprises a rubidium cation, a 2,4-dinitro­phenoxide anion and a water mol­ecule. The Rb⁺ cation is 11-coordinated by O atoms from 2,4-dinitro­phenolate anions and water mol­ecules. The metal centre is firstly coordinated by two μ₃-H₂O to form a one-dimensional ladder-shaped unit, [Rb₂(μ₃-H₂O)₂], which is further linked by 2,4-dinitro­phenolate to give the three-dimensional framework of the title compound. The crystal structure involves O—H⋯O hydrogen bonds.

Phosphato, Chromato, and Perrhenato Complexes of Titanium(IV) and Zirconium(IV) Containing Kläui's Tripodal Ligand

Treatment of titanyl sulfate in dilute sulfuric acid with 1 equiv of NaL(OEt) (L(OEt)(-) = [(eta(5)-C(5)H(5))Co{P(O)(OEt)(2)](3)](-)) in the presence of Na(3)PO(4) and Na(4)P(2)O(7) led to isolation of [(L(OEt)Ti)(3)(mu-O)(3)(mu(3-)PO(4))] (1) and [(L(OEt)Ti)(2)(mu-O)(mu-P(2)O(7))] (2), respectively. The structure of 1 consists of a Ti(3)O(3) core capped by a mu(3)-phosphato group. In 2, the [P(2)O(7)](4-) ligands binds to the two Ti's in a mu:eta(2),eta(2) fashion. Treatment of titanyl sulfate in dilute sulfuric acid with NaL(OEt) and 1.5 equiv of Na(2)Cr(2)O(7) gave [(L(OEt)Ti)(2)(mu-CrO(4))(3)] (3) that contains two L(OEt)Ti(3+) fragments bridged by three mu-CrO(4)(2-)-O,O' ligands. Complex 3 can act as a 6-electron oxidant and oxidize benzyl alcohol to give ca. 3 equiv of benzaldehyde. Treatment of [L(OEt)Ti(OTf)(3)] (OTf(-) = triflate) with [n-Bu(4)N][ReO(4)] afforded [[L(OEt)Ti(ReO(4))(2)](2)(mu-O)] (4). Treatment of [L(OEt)MF(3)] (M = Ti and Zr) with 3 equiv of [ReO(3)(OSiMe(3))] afforded [L(OEt)Ti(ReO(4))(3)] (5) and [L(OEt)Zr(ReO(4))(3)(H(2)O)] (6), respectively. Treatment of [L(OEt)MF(3)] with 2 equiv of [ReO(3)(OSiMe(3))] afforded [L(OEt)Ti(ReO(4))(2)F] (7) and [[L(OEt)Zr(ReO(4))(2)](2)(mu-F)(2)] (8), respectively, which reacted with Me(3)SiOTf to give [L(OEt)M(ReO(4))(2)(OTf)] (M = Ti (9), Zr (10)). Hydrolysis of [L(OEt)Zr(OTf)(3)] (11) with Na(2)WO(4).xH(2)O and wet CH(2)Cl(2) afforded the hydroxo-bridged complexes [[L(OEt)Zr(H(2)O)](3)(mu-OH)(3)(mu(3)-O)][OTf](4) (12) and [[L(OEt)Zr(H(2)O)(2)](2)(mu-OH)(2)][OTf](4) (13), respectively. The solid-state structures of 1-3, 6, and 11-13 have been established by X-ray crystallography. The L(OEt)Ti(IV) complexes can catalyze oxidation of methyl p-tolyl sulfide with tert-butyl hydroperoxide. The bimetallic Ti/ Re complexes 5 and 9 were found to be more active catalysts for the sulfide oxidation than other Ti(IV) complexes presumably because Re alkylperoxo species are involved as the reactive intermediates.

Synthesis, Structure, and Reactivity of O-Donor Ir(III) Complexes: C−H Activation Studies with Benzene

Various new thermally air- and water-stable alkyl and aryl analogues of (acac-O,O)2Ir(R)(L), R-Ir-L (acac-O,O = kappa2-O,O-acetylacetonate, -Ir- is the trans-(acac-O,O)2Ir(III) motif, R = CH3, C2H5, Ph, PhCH2CH2, L = Py) have been synthesized using the dinuclear complex [Ir(mu-acac-O,O,C3)-(acac-O,O)(acac-C3)]2, [acac-C-Ir]2, or acac-C-Ir-H2O. The dinuclear Ir (III) complexes, [Ir(mu-acac-O,O,C3)-(acac-O,O)(R)]2 (R = alkyl), show fluxional behavior with a five-coordinate, 16 electron complex by a dissociative pathway. The pyridine adducts, R-Ir-Py, undergo degenerate Py exchange via a dissociative mechanism with activation parameters for Ph-Ir-Py (deltaH++ = 22.8 +/- 0.5 kcal/mol; deltaS++ = 8.4 +/- 1.6 eu; deltaG++298 K) = 20.3 +/- 1.0 kcal/mol) and CH3-Ir-Py (deltaH++ = 19.9 +/- 1.4 kcal/mol; deltaS++ = 4.4 +/- 5.5 eu; deltaG++298 K) = 18.6 +/- 0.5 kcal/mol). The trans complex, Ph-Ir-Py, undergoes quantitatively trans-cis isomerization to generate cis-Ph-Ir-Py on heating. All the R-Ir-Py complexes undergo quantitative, intermolecular CH activation reactions with benzene to generate Ph-Ir-Py and RH. The activation parameters (deltaS++ =11.5 +/- 3.0 eu; deltaH++ = 41.1 +/- 1.1 kcal/mol; deltaG++298 K = 37.7 +/- 1.0 kcal/mol) for CH activation were obtained using CH3-Ir-Py as starting material at a constant ratio of [Py]/[C6D6] = 0.045. Overall the CH activation reaction with R-Ir-Py has been shown to proceed via four key steps: (A) pre-equilibrium loss of pyridine that generates a trans-five-coordinate, square pyramidal intermediate; (B) unimolecular, isomerization of the trans-five-coordinate to generate a cis-five-coordinate intermediate, cis-R-Ir- square; (C) rate-determining coordination of this species to benzene to generate a discrete benzene complex, cis-R-Ir-PhH; and (D) rapid C-H cleavage. Kinetic isotope effects on the CH activation with mixtures of C6H6/C6D6 (KIE = 1) and with 1,3,5-C6H3D3 (KIE approximately 3.2 at 110 degrees C) are consistent with this reaction mechanism.

Rational assembly of a 3D metal–organic framework for gas adsorption with predesigned cubic building blocks and 1D open channels

A novel 3D metal-organic framework with predesigned cubic building blocks and 1D open channels exhibiting significant N2 adsorption has been synthesized and characterized by single crystal X-ray diffraction analysis.

Titanium(IV) and Zirconium(IV) Sulfato Complexes Containing the Kläui Tripodal Ligand: Molecular Models of Sulfated Metal Oxide Surfaces

Treatment of titanyl sulfate in about 60 mM sulfuric acid with NaL(OEt) (L(OEt) (-)=[(eta(5)-C(5)H(5))Co{P(O)(OEt)(2)}(3)](-)) afforded the mu-sulfato complex [(L(OEt)Ti)(2)(mu-O)(2)(mu-SO(4))] (2). In more concentrated sulfuric acid (>1 M), the same reaction yielded the di-mu-sulfato complex [(L(OEt)Ti)(2)(mu-O)(mu-SO(4))(2)] (3). Reaction of 2 with HOTf (OTf=triflate, CF(3)SO(3)) gave the tris(triflato) complex [L(OEt)Ti(OTf)(3)] (4), whereas treatment of 2 with Ag(OTf) in CH(2)Cl(2) afforded the sulfato-capped trinuclear complex [{(L(OEt))(3)Ti(3)(mu-O)(3)}(mu(3)-SO(4)){Ag(OTf)}][OTf] (5), in which the Ag(OTf) moiety binds to a mu-oxo group in the Ti(3)(mu-O)(3) core. Reaction of 2 in H(2)O with Ba(NO(3))(2) afforded the tetranuclear complex (L(OEt))(4)Ti(4)(mu-O)(6) (6). Treatment of 2 with [{Rh(cod)Cl}(2)] (cod=1,5-cyclooctadiene), [Re(CO)(5)Cl], and [Ru(tBu(2)bpy)(PPh(3))(2)Cl(2)] (tBu(2)bpy=4,4'-di-tert-butyl-2,2'-dipyridyl) in the presence of Ag(OTf) afforded the heterometallic complexes [(L(OEt))(2)Ti(2)(O)(2)(SO(4)){Rh(cod)}(2)][OTf](2) (7), [(L(OEt))(2)Ti(O)(2)(SO(4)){Re(CO)(3)}][OTf] (8), and [{(L(OEt))(2)Ti(2)(mu-O)}(mu(3)-SO(4))(mu-O)(2){Ru(PPh(3))(tBu(2)bpy)}][OTf](2) (9), respectively. Complex 9 is paramagnetic with a measured magnetic moment of about 2.4 mu(B). Treatment of zirconyl nitrate with NaL(OEt) in 3.5 M sulfuric acid afforded [(L(OEt))(2)Zr(NO(3))][L(OEt)Zr(SO(4))(NO(3))] (10). Reaction of ZrCl(4) in 1.8 M sulfuric acid with NaL(OEt) in the presence Na(2)SO(4) gave the mu-sulfato-bridged complex [L(OEt)Zr(SO(4))(H(2)O)](2)(mu-SO(4)) (11). Treatment of 11 with triflic acid afforded [(L(OEt))(2)Zr][OTf](2) (12), whereas reaction of 11 with Ag(OTf) afforded a mixture of 12 and trinuclear [{L(OEt)Zr(SO(4))(H(2)O)}(3)(mu(3)-SO(4))][OTf] (13). The Zr(IV) triflato complex [L(OEt)Zr(OTf)(3)] (14) was prepared by reaction of L(OEt)ZrF(3) with Me(3)SiOTf. Complexes 4 and 14 can catalyze the Diels-Alder reaction of 1,3-cyclohexadiene with acrolein in good selectivity. Complexes 2-5, 9-11, and 13 have been characterized by X-ray crystallography.

Alkane C−H Activation and Catalysis by an O-Donor Ligated Iridium Complex

The first examples of well-defined, O-donor ligated, late-metal complexes that are competent for alkane C-H activation are reported. These complexes exhibit thermal and protic stability and are efficient catalysts for H/D exchange reactions with alkanes.

Half-sandwich titanium(IV) complexes with Kläui's tripod ligand

Treatment of [Ti(O-i-Pr)(2)Cl(2)] with NaL(OEt) (L(OEt)(-) = [CpCo[P(O)(OEt)(2)](3)](-), Cp = eta(5)-C(5)H(5)) afforded [L(OEt)Ti(O-i-Pr)(2)Cl] that reacted with HCl in ether to give [L(OEt)TiCl(3)] (1). The average Ti-O and Ti-Cl distances in 1 are 1.975 and 2.293 A, respectively. Reaction of titanyl sulfate with NaL(OEt) in water followed by addition of HBF(4) afforded [L(OEt)TiF(3)] (2), the Ti-O and Ti-F distances of which are 2.020(2) and 1.792(2) A, respectively. The Zr(IV) analogue [L(OEt)ZrF(3)] (3) was prepared similarly from zirconyl nitrate, NaL(Oet), and HBF(4) in water. The Zr-O and average Zr-F distances in 3 are 2.139(2) and 1.938(2) A, respectively. Treatment of 1 with tetrachlorocatechol (H(2)Cl(4)cat) afforded [L(OEt)Ti(Cl(4)cat)Cl] (4). The average Ti-O(P), Ti-O(C), and Ti-Cl distances in 4 are 1.972, 1.926, and 2.334 A, respectively. Hydrolysis of 4 in the presence of Et(3)N yielded the mu-oxo dimer [(L(OEt))(2)Ti(2)(Cl(4)cat)(2)(mu-O)] (5). The average Ti-O(P), Ti-O(C), and Ti-O(Ti) distances in 5 are 2.027, 1.926, and 1.7977(9) A. Treatment of 1 with 1,1'-binaphthol (BINOLH(2)) in the presence of Et(3)N afforded [(L(OEt))(2)Ti(2)(mu-O)(2)(mu-BINOL)] x 2BINOLH(2) (6.2BINOLH(2)). Complex 1 is capable of catalyzing ring opening of epoxides with Me(3)SiN(3) under solvent-free conditions presumably via a Ti-azide intermediate.

Beryllium(II) Complexes of the Kläui Tripodal Ligand Cyclopentadienyltris(diethylphosphito-P)cobaltate(−)

The interactions of the beryllium(II) ion with the cyclopentadienyltris(diethylphosphito-P)cobaltate monoanion, L(-), have been investigated, in aqueous solution, by synthetic methods, potentiometry, ESMS, and (1)H, (31)P, and (9)Be NMR spectroscopy. L(-) has been found able to displace either two or three water molecules in the beryllium(II) coordination sphere, to form mononuclear, dinuclear, and trinuclear derivatives, in which the metal ion is pseudotetrahedrally coordinated. The species [BeL(H(2)O)](+) and [Be(2)L(2)(mu-OH)](+) have been identified in solution while complexes of formula BeL(2) and [Be(3)L(4)](ClO(4))(2) have been isolated as solid materials. The species [BeL(OPPh(2))](+), closely related to [BeL(H(2)O)](+), has been characterized in acetone solution and isolated as tetraphenylborate salt. The structure of the unusual trimeric complex [Be(3)L(4)](2+) has been elucidated by an unprecedented 2D (9)Be-(31)P NMR correlation spectrum showing the presence of a single central beryllium nucleus and two equivalent terminal beryllium nuclei. The three beryllium centers are held together by four cobaltate ligands, which display two different bonding modes: two ligands are terminally linked with all the three oxygen donors to one terminal beryllium, and the other two bridge two metal centers, sharing the oxygen donors between central and terminal beryllium atoms.

Synthesis and Complexation Properties of the Anions (eta(5)-C(5)Me(5))Ru(PR(2)O)(3)(2)(-) as Ligands

Reaction of [(eta(5)-C(5)Me(5))Ru(OMe)](2) (2) with HP(O)(OR)(2) gave the novel tripod ligands H(2)(eta(5)-C(5)Me(5))Ru{PO(OR)(2)}(3) (R = Me, Et, (i)Pr, H(2)1). H(2)(eta(5)-C(5)Me(5))Ru{PO(Ph(2))}(3) was formed with HP(O)Ph(2). [(eta(5)-C(5)Me(5))RuCl(2)](2) (3) with NaP(O)(OEt)(2) similarly gave Na(2)(eta(5)-C(5)Me(5))Ru{PO(OEt)(2)}(3) (Na(2)1; Na(2)L). Either the hydrogen form or the sodium salt was reacted with main group and transition metal halides to yield complexes [ML(2)](n)()(-) (M = Si(IV), Ti(IV), Nb(IV), n = 0; Co(II), n = 2; Cr(III), Fe(III), n = 1), or complexes of the form LMX with MX = BPh, VO. Reaction of Na(2)(eta(5)-C(5)Me(5))Ru{PO(Ph(2))}(3) with TiCl(4) gave intermediately [LTiCl(2)](2) which readily hydrolyzed on chromatography over Al(2)O(3) to trinuclear (LTiO)(3)(&mgr;(3)-O)H(2). The latter was characterized by X-ray structure analysis. It crystallizes in the cubic space group Pa3 (No. 205), z = 8, a = 30.83(1) Å, V = 29300(30) Å(3). From the reaction of Na(2)1 and 3 under appropriate conditions, the mixed valence complex LRu(eta(5)-C(5)Me(5)) (4) was isolated. Compounds were characterized by spectroscopy and electrochemistry. From absorption spectra of the Co(II) and the Cr(III) complex ligand field parameters Delta(o) = 902 and 1450 cm(-)(1), respectively, were derived, placing 1 near F(-) in the spectrochemical series.

Vanadium Hydrotris(pyrazolyl)borate Complexes of Diphenyl Phosphate. Heterometallic Complexes of the [LV{(PhO)(2)PO(2)}(3)](-) Fragment

The synthesis and characterization of nine trinuclear, mixed metal complexes of the type [LV{&mgr;-(PhO)(2)PO(2)}(3)](2)M, where the vanadium is in the 3+ oxidation state, L = hydrotris(pyrazolyl)borate, and M = Ba(II) (1), Ca(II) (2), Mg(II) (3), Mn(II) (4), Co(II) (5), Ni(II) (6), Fe(II) (7), 2 Na(I) (8), Al(III) (9), and La(III) (10), are described. X-ray crystal structural analysis of 1, 3, and 4 gave the following parameters: 1, C(92)H(84)B(2)N(12)O(24)P(6)Cl(4)BaV(2), C2/c, a = 26.730(5) Å, b = 15.521(3) Å, c = 27.648(6) Å, beta = 100.53(3) degrees, Z = 4; 3, C(94)H(80)B(2)N(14)O(24)P(6)MgV(2), P&onemacr;, a = 13.410(3) Å, b = 14.179(3) Å, c = 15.694(3) Å, alpha = 112.22(3) degrees, beta = 101.31(3) degrees, gamma = 106.15(3) degrees, Z = 1; 4, C(111)H(80)B(2)N(12)O(28)P(6)MnV(2), R&thremacr;c, a = 18.670(3) Å, b = 18.671(3) Å, c = 61.114(12) Å, Z = 6. Magnetic measurements indicate that compounds containing an integral spin central ion display moderate antiferromagnetic coupling while those with half-integral spins give more complex behavior.