Sulfur Atoms as Ligands in Metal Complexes

Abstract

Dedicated to Professor Helmut Behrens on the occasion of his 60th birthdayThe types of sulfur bonding-as sulfane or sulfide-encountered in the molecules of maingroup elements are almost unknown in the chemistry of metal complexes, where the sulfur atoms function instead as two-electron donors by bridging two metal atoms, as four-electron donors by bridging three or four metal atoms, or as six-electron donors by incorporation between four metal atoms. In such complexes, the metal-metal bond can be modified over a wide range by chemical or electrochemical variation of the number of electrons present. The readiness with which polynuclear complexes containing metals and sulfur undergo redox reactions is also utilized by Nature in the active sites of some redox proteins.

Reactions of Terminal and Bridging Thiol Di-μ-methylene Dirhodium Complexes with Alkynes to Afford the Corresponding Ethenethiolate Complexes. Remarkable C−C Bond Formation between Two μ-CH2 and Alkynes on the Bridging Ethenethiolate Complexes

“…As early as 1975 it was indicated that the reactivity of M(µ-SH)M groups is different from that of M-SH groups and is low because one lone pair of (5) Rh-C(1)′ 2.051(4) S-C (12) 1.722 (4) O(1)-C (14) 1.322(7) O(2)-C (14) 1.195 (7) O (3)-C(17) 1.331(7) O(4)-C (17) 1.213 (7) C(12)-C (13) 1.364(6) C(12)-C (14) 1.500 (7) C(13)-C(17) 1.460 (6) Bond Angles S-Rh-Rh′ 90.86 (3) (13) 125.9(5) electrons on the sulfur atom of µ-SH is blocked in order to coordinate to two metal atoms. 18 However, recent studies have revealed that the bridging thiol ligands in dinuclear complexes have rather high reactivities and show additions to alkynes. 2-4 The reaction of the cationic bridging thiol complex [(RhCp*) 2 (µ-CH 2 ) 2 (µ-SH)]-(BPh 4 ) (3) with 1 equiv of dimethyl acetylenedicarboxylate or carbyl propiolate in a mixed solvent of CH 2 Cl 2 / MeOH (5:1) gave [(RhCp*) 2 (µ-CH 2 ) 2 (µ-SCR 1 dCHR 2 )]-(BPh 4 ) (4a, R 1 , R 2 ) COOMe; 4b, R 1 ) H, R 2 ) COOPh; 4c, R 1 ) H, R 2 ) COOMe) (eq 3).…”

Chiral Thiophosphoramide and Thioamide Ligands in Catalytic Asymmetric Carbon-Carbon Bond-Formation Reactions

“…This could be due to the fact that the primary product can easily react to yield sulfhydryl or multinuclear complexes with bridging sulfur ligands. 9 The first stable hydrogen sulfide complexes were reported in 1976. 10 Other sulfur-containing ligands, such as thioethers, 11 oxides of sulfur, 12 thioureas, 13 dithiobiurets, 14 dithiolenes, 15 phosphine sulfides, 16 aminosubstituted phosphine sulfides, 17 sulfur-containing oxazolines 18 and polysulfides 19 are widely utilized in organic reactions.…”

Molecular Mercury Zinc Sulfides

“…This has long been known for classical [1] as well as for organometallic [2] coordination chemistry. In recent years Fenske and co-workers have provided impressive examples of high-nuclearity clusters constructed by the nucleation of metal ions around sulfide ions.…”

“…Our present work in this field, after past experiences with polynuclear organometallic complexes, [2] results from our attempts to construct monofunctional zinc complexes for biomimetic and catalytic studies. Since sulfur ligation of zinc is a common feature of both industrially applied and biological zinc species, we have also experimented with thiolates and sulfide as ligands for zinc.…”