Polysulfide ligands reactions

Reactions of metal halides with polysulfide dianions are useful methods for the synthesis of polysulfido complexes of main group elements and transition metals. In most of these reactions, similarly to other methods, the chain lengths and coordination types of the polysulfide ligands depend on the other ligands coordinated to the metal, on the ratio between the metal and sulfur, on the reaction temperature, and other parameters. 

Bicyclo(4.4.1 Jundecapentaene complexes with group VI B metals, 12 237 Bidentate ligands, reactions with tetracyano complexes containing oxo or nitrido ligands, 40 310-313 Bidentate oligopyridines, 30 72-73 Bidentate polysulfide complexes, bond lengths, 31 114... 

Since (BzS)2S is very reactive, the reaction and the polysulfide ligands it produces will be enhanced. This probably accounts for the high viscosity of the solution observed after the reaction of (BzS)2S and Et2Zn at a 5 1 ratio. If the gel contains residual benzene groups, the presence of these bulky groups further enhances the linear polymerization and stability of the gel. 

We previously reported the synthesis of thiol-modified silica-polyamine composite using ethylene sulfide. Although the reaction of ethylene sulfide with WP-1 gave a material that had excellent mercury capture characteristics, this ligand is toxic and difficult to make and handle. In addition, ethylene sulfide polymerizes with itself in the presence of nucleophiles therefore, we could not tell if we were dealing with an amino-thiol ligand (Fig. 16 ) or a polysulfide ligand (Fig. 165).27... 

The dinuclear ion Mo2(S2) g (F - prepared from the reaction of molybdate and polysulfide solution (13) is a usehil starting material for the preparation of dinuclear sulfur complexes. These disulfide ligands are reactive toward replacement or reduction to give complexes containing the Mo2S " 4 core (Fig. 3f). 

A number of structures with S-rich dianion ligands have been determined (297-299).831 832 For example, (297) can be synthesized by the reaction of [Ni(CN)4]2 with polysulfide.833 Upon further reaction with CS2 or substituted acetylenes it forms perthiocarbonato and dithiolene complexes, respectively. 

Polysulfides of several metals can be prepared by reaction of the metals with excess sulfur in liquid NH3 (group IA metals) or by heating sulfur with the molten metal sulfide. The polysulfide ion binds to metals to form coordination compounds in which it is attached to the metal by both sulfur atoms (as a so-called bidentate ligand). One example is an unusual titanium complex containing the S52-ion that is produced by the following reaction (the use of h to denote the bonding mode of the cyclo-pentadienyl ion is explained in Chapter 16) ... 

Reaction of metal complexes with S is a convenient method for directly introducing the ligand by substitution of other ligands. For example, NajS2 or polysulfide solutions can be used for this purpose (77, 107, 108, 120,146). 

The reaction of ammonium polysulfide with nickel(II) acetate in MeOH solution gave the black diamagnetic square planar complex [Ni(S4)2](NEt4)2 (266) which contains the S4 anion as the unique ligand.1940... 

In each case, it is the carbonyl ligands which are displaced rather than the nitrosyl ligands. In a similar manner, the reaction of polysulfide (23, 27) with [Fe(CO)3NO] causes displacement of carbonyl, rather than nitrosyl, to yield [Fe4S3(NO)7] (see Section II,A). 

The Schiff bases with two benzylidenimine residues bridged by polysulfide chains of different lengths can act as potentially bidentate ligands. These compounds have been obtained by reaction of sulfur with benzylamine in the presence of PbO. They have been characterized by X-ray, NMR, IR and chromatographic techniques.49 The structural analysis of three of them, having n = 2,3 and 4 and R = H, showed that the overall geometry is dominated by the conformation of the polysulfide chain.50... 

A great variety of binary Mo-S complex anions is formed and can be isolated in reactions of the tetrathiomolybdate anion [MoS ] " with various suinde and polysulfide anions. The nature of the anionic products that can be isolated from these reactions depends on (a) the amount of excess sulfur used (and the types of ligands present in the reaction mixtures), (b) the type of counterion used in the isolation of the complex anions, and (c) the type of solvent employed in the synthetic procedure. In a recent article, we described a scheme that interrelates the various [Mo2(S),(S2)6-,] anions. In this scheme (Fig. 1), any of the six homologs can hypothetically be obtained from any other by either the addition of sulfur, or the abstraction of sulfur by triphenylphosphine. Experimentally, the correctness of this scheme has been verified by the successful synthesis of most of the [Mo2(S) (S2)6 ] complexes, or of their internal redox isomers. In the [Mo2(S), (82)6 series, the homologs with n = 4, 5, and 6 have been characterized structurally. Those with n = 2 and 3 have been characterized structurally as the internal-redox isomers, [(S4)Mo(S)(//-S)2(S)Mo S2)] (ref. 3) and... 

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