Thiolates and thioethers

Ni11 complexes of various amine/thiophenolate ligands have been investigated (for Ni complexes of ortho-aminothiophenol see Section 6.3.4.9.2(iv)). Thiophenolate is expected to exhibit decreased bridging tendency compared to aliphatic thiolates, but complexes (466) and (467) still consist of two pseudo-octahedral NiL fragments bridged via thiolate donors. In contrast to the parent complex (466), the thiolate and thioether donors in (467) coordinate cis to the Ni center... 

With establishment of the crystal structure, three major features concerning the electronic structure of the blue copper site can be addressed. These features are 1) the nature of the thiolate and thioether bonds, 2) the nature of the ground state wavefunction and 3) the extent of covalency. We have also become strongly involved in using photoelectron spectroscopy as a powerful approach toward determining covalency in transition metal complexes. These will be discussed in turn. 

After administration, the drug circulates in the blood, primarily as the chloride (for cisplatin), or as another rather inert form (such as the biscar-boxylate in carboplatin). In the blood, also reactions with proteins and rescue agents can take place. Upon passing through cell walls (either actively or passively), intracellular reactions with peptides and proteins may take place, presumably followed by transfer to nucleic acids. Given the strong (kinetic) preference of Pt compounds to react with class-B donor atoms (such as those from thiolates and thioethers), binding to nucleic-acid bases (a thermodynamic end product) must at least occur partially via labile intermediates. 

These complexes all exhibit a configuration in which the thiolate and thioether donors pairwise adopt trans positions, and have short Fe-donor bond distances indicating the absence of antibonding electrons, which is shown exemplarily by [Fe(N2H4)(pyS4)] (67), [Fe(CO)(pyS4)] (31), and [Fe(CO) (NhS4)] (28) in Fig. 8. 

Table 89 Preparations Some Tri-, Quadri- and Sexi-dentate Thiolate and Thioether Chelates of Cobalt(III)...

Efforts to optimize rhodium-based systems for methanol carbonylation led to the development of new supporting ligands containing phosphorus and sulfur donor atoms, both thiolates and thioethers, such as those used in the preparation of complexes (20) and (21). Ligands such as 2-diphenylphosphinothiolate have been shown to give rise to complexes that exhibit higher activities, up to four times faster, for the carbonylation of methanol compared to [Rh(CO)2l2] . ... 

It is of particular interest to compare the Fe "-SR and Fe " -SR2 stretching frequencies in connection with cytochrome P-450 and cytochrome c having the thiolate and thioether ligands, respectively. Oshio et al. observed IR bands attributable to the Vpe-sR- and Vpe-sRj modes. The results are also included in Table 8. The Vpe-SR- band appears around 333-341 cm , which are appreciably lower than 351 cm of the vpe-sR-band of oxidized cytochrome P-450 observed with RR spectroscopy. ... 

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