Crown thioether chemistry of iron(II/III). Synthesis and characterization of low-spin bis(1,4,7-trithiacyclononane)iron(III) and crystal structure of [FeII([9]aneS3)([9]aneS3(O))](ClO4)2.2NaClO4.H2O

Isomers in the chemistry of iron coordination compounds

The coordination chemistry of iron covers a wide field, as shown by a survey covering the crystallographic and structural data of almost one thousand and three hundred coordination complexes. About 6.7% of these complexes exist as isomers and are summarized in this review. Included are distortion (96.6%) and cis — trans (3.4%) isomers. These are discussed in terms of the coordination about the iron atom, bond length and interbond angles. Distortion isomers, differing only by degree of distortion in Fe-L, Fe-L-Fe and L-Fe-L parameters, are the most common. Iron is found in the oxidation states zero, +2 and +3 of which +3 is most common. The stereochemistry around iron centers are tetrahedral, five — coordinated (mostly trigonal — bipyramid) and six — coordinated. The most common ligands have O and N donor sites.

Synthesis and properties of calix[4]arene telluropodant ethers as Ag+ selective sensors and Ag+, Hg2+ extractants

Three novel phenyltelluroalkoxyl functionalized tweezer-like calix[4]arenes 6-8 and two monophenyltelluropropoxyl functionalized calix[4]arenes 10 (cone conformer) and 12 (partial cone conformer) were synthesized and characterized. They are good Ag(+)-selective ionophores in ion-selective electrodes evaluated by electromotive force measurements of polymer membrane electrodes. The tweezer-like ionophores 6-8 showed excellent extraction ability towards Ag(+) and Hg(2+).

Sulfimidation of thioether groups--a versatile method for modifying and linking thia/oxa crowns

Reaction of the mixed thioether/ether crowns [9]aneO2S , [12]aneO3S and [18]aneO4S2 with one mol. equivalent of the aminating agent MSH (o-mesitylsulfonylhydroxylamine) in Et2O results in the formation of the mono-sulfimidated systems {[9]aneO2(S=NH2)}+, {[12]aneO3(S=NH2)}+ and {[18]aneO4S(S=NH2)}+, while using two mol. equivalents of MSH with gives the disulfimidium cation {[18]aneO4(S=NH2)2}2+. All of these species have been isolated in good yields as the [mesSO3]- (mes=2,4,6-Me3C6H2) salts and can be readily converted to the [BPh4]- salts by metathesis with Na[BPh4]. Treatment of or with lithium diisopropylamide (LDA) and N-bromosuccinimide (NBS) at -78 degrees C, followed by addition of a further equivalent of the parent thia/oxa crown, gives monocationic N-bridged sulfimide bicyclic compounds ( and respectively), in which the crowns are linked by the sulfimidic nitrogen. Reaction of with LDA and NBS leads to formation of the {([18]aneO4S2)N}+ cation which exhibits an intramolecular S-N-S bridge. Crystallographic studies on representative examples of each compound type are described, together with their spectroscopic properties.

Precursors to [FeFe]-hydrogenase models: syntheses of Fe2(SR)2(CO)6 from CO-free iron sources

This report describes routes to iron dithiolato carbonyls that do not require preformed iron carbonyls. The reaction of FeCl 2, Zn, and Q 2S 2C n H 2 n (Q (+) = Na (+), Et 3NH (+)) under an atmosphere of CO affords Fe 2(S 2C n H 2 n )(CO) 6 ( n = 2, 3) in yields >70%. The method was employed to prepare Fe 2(S 2C 2H 4)( (13)CO) 6. Treatment of these carbonylated mixtures with tertiary phosphines, instead of Zn, gave the ferrous species Fe 3(S 2C 3H 6) 3(CO) 4(PR 3) 2, for R = Et, Bu, and Ph. Like the related complex Fe 3(SPh) 6(CO) 6, these compounds consist of a linear arrangement of three conjoined face-shared octahedral centers. Omitting the phosphine but with an excess of dithiolate, we obtained the related mixed-valence triiron species [Fe 3(S 2C n H 2 n ) 4(CO) 4] (-). The highly reducing all-ferrous species [Fe 3(S 2C n H 2 n ) 4(CO) 4] (2-) is implicated as an intermediate in this transformation. Reactive forms of iron, prepared by the method of Rieke, also combined with dithiols under a CO atmosphere to give Fe 2(S 2C n H 2 n )(CO) 6 in modest yields under mild conditions. Studies on the order of addition indicate that ferrous thiolates are formed prior to the onset of carbonylation. Crystallographic characterization demonstrated that the complexes Fe 3(S 2C 3H 6) 3(CO) 4(PEt 3) 2 and PBnPh 3[Fe 3(S 2C 3H 6) 4(CO) 4] feature high-spin ferrous and low-spin ferric as the central metal, respectively.

Sulfimidation—a new and versatile strategy for the post ring-closure derivatisation of mixed thia/oxa crowns

Reaction of [18]aneO(5)S with the aminating agent MSH results in the {[18]aneO(5)SNH(2)}+ cation which may be converted through to the linked crown system [({[18]aneO(5)S}(2)N)]+ via deprotonation, bromination and reaction with the parent crown; significantly, despite their positive charge, both systems can coordinate sodium cations to the ether linkages.

Thiophenophane metal complexes IV. Effects from ligand changes outside the coordination sphere

Preparation of two thiophenophane polythioether macrocycles and 11 of their complexes of Cu(I), Cu(II), Ag(I), and Pd(II) is described. The single crystal X-ray structure of [(CuBr)2(L1)x is reported: space group Pcma, a = 8.7120(6), b = 10.7791(5), c = 12.0929(5) Å, Z = 2, Rf = 0.052, Rw = 0.036 for 521 reflections. Variable-temperature magnetic susceptibility measurements for [(CuCl2)2(L1)] and [(CuCl2)2(L2)] reveal weak antiferromagnetic and weak ferromagnetic coupling, respectively. Cyclic voltammograms of these compounds display two unequal waves in acetonitrile solvent but only one in nitromethane or dimethyl sulfoxide. 1H NMR spectra of {[(η-C3H5)Pd]2(L1)}{PF6}2 and {[(η-C3H5)Pd]2(L2)}{PF6}2 in various solvents show different temperature responses. These magnetic, electrochemical, and NMR effects are discussed in the light of structural differences at sites in the two ligands that are outside the coordination spheres. Key words: magnetic susceptibility, copper, thioether, electrochemistry.

Preparations for 1,4,7,11,14,17-hexa-thiacycloeicosane, 1,4,7-trithiecan-9-ol, 1,11 -dioxa-4,8,14,18-tetrathia-cycloeicosane, 1 -oxa-4,8-dithiacyclo-decane, and some complexes of iron, cobalt, nickel, and palladium

Preparations are reported for the title ligands (L1–L4, respectively) and for [Co(L1)][ClO4]2, [Ni(L1)][ClO4]2, [{Pd(η3-C3H5)}2(L1)][ClO4]2, [Co(L2)2][ClO4]2, [Ni(L2)2][ClO4]2, [Co(L3)][ClO4]2, and [Ni(L3)2][ClO4]2. Clarification of earlier reports of L2 and some of its complexes has been achieved by X-ray crystallographic characterization. Crystal data for orthorhombic [Ni(L1)][ClO4]2: space group Pna21 (No. 33); a = 13.270(4), b = 16.564(4), c = 11.348(4) Å; Z = 4; R = 0.047, Rw = 0.040 for 1474 reflections. For monoclinic [Ni(L2)2][ClO4]2: space group P21/c (No. 14); a = 7.617(3), b = 18.034(3), c = 9.098(2) Å, β = 91.58(2)°; Z = 2; R = 0.046, Rw = 0.039 for 1487 reflections. For tetragonal [Co(L3)][ClO4]2: space group [Formula: see text] (No. 121); a = 13.840(5), c = 14.902(4) Å; Z = 4; R = 0.054, Rw = 0.058 for 974 reflections. The new complexes and previously reported [Fe(L1)][ClO4]2have been examined by cyclic voltammetry, NMR, ESR, electronic spectroscopy, and magnetic susceptibility measurements. The influence of L2's extra-cyclic hydroxyl, of changes in M—S lengths, and of O for S substitution on structural, magnetic, redox, and spectroscopic properties has been studied. Keywords: X-ray structures, electrochemistry, magnetic phenomena.