Neutral sulfur donors

Neutral sulfur donors are softer and more polarizable than the neutral oxygen donors of Section 2.7.1.4. Thioethers and sulfoxides are the most common neutral sulfur donors. The trans influence of neutral sulfur donors is greater than that of ethers and is more comparable to that of amines, as based on M-Cl bond lengths. The strength of the metal-thioether bond is usually stronger than that of the metal-amine bond, but weaker than the metal-phosphorus bond. They lie in the spectrochemical series in between chloride and phosphine ligands. 

Two sulfur-donor ligands with accompanying carbon or phosphorus donors. 

DMSO complexes have also been prepared and studied in contexts related to organome-tallic chemistiy. DMSO binds to low-valent late metals through the electron pair on sulfur, to harder high-valent metals through the electron pairs on oxygen, and to some complexes with a mixture of 0- and S-bound forms. Palladium complexes of DMSO and of biden-tate sulfoxide ligands have been used as catalysts for the oxidative cyclization of enols and 

Two DMSO complexes of organometallic systems and a ruthenium DMSO complex with mixed S- and 0-donor atoms. 

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Barriers of 12.5-15.5 kcal/mol for neutral CpMo(CO)(MeC=CMe)-(SR) complexes are quite similar to rotational barriers in cationic complexes (74). Given the 7r acidity of CO and the tt basicity of SR-, these barriers are surprisingly small. Sulfur donor ligands tend to be electronically flexible, and the soft thiolate may facilitate alkyne rotation by simultaneous rotation of the thiolate substituent. 

Reactions of [Ml2(CO),(NCMe)21 with Neutral Oxygen and Sulfur Donor Ligands... 

Scheme 7), which can be converted into one another by either chemical or electrochemical reactions (35, 36). When considering the structures depicted in Scheme 7 for [Ni(S2C2H2)2r the oxidation state of the nickel should be Ni(II), Ni(III), or Ni(IV), for n 2, 1, and 0, respectively. However, it is rather unlikely that highly polarizable sulfur donor atoms could stabilize the Ni(IV) high oxidation state in the neutral species. 

CY) (C0)9 or Co3(m3-CC(0)Y)(CO)9. The latter may be formed by solvolysis to the ketenylidene cation. The former products are most likely formed via radical reactions. On the other hand, neutral Lewis bases L can replace the chloride from H30s3(/x3-CC1)(C0)9 to form H20s3(/u-3-CL)(C0)9, where L is a nitrogen, phosphorus or sulfur donor. ... 

Figure 4 compares the relative a- and 7c-donor ability of three distinct sulfur donors thiolate, sulfinate, and thioether 17, 23, 24, 26-28). Based on simple charge considerations, both the thiolate and sulfinate donors are anionic, while the thioether is neutral. In terms of a-donor ability, the thiolato sulfur should be stronger than the sulfinate since the oxygen atoms of the latter withdraw significant electron density away from sulfur. The neutral thioether is the poorest a-donor. In terms of 7c-donor ability, only the thiolate sulfur possess the... 

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