Destabilizing d.pi.-p.pi. orbital interactions and the alkylation reactions of iron(II)-thiolate complexes

Abstract

Cl, CF3, N02) the -type interaction between formally occupied metal d orbitals and the sulfur lone pair that is principally 3p in character has been modeled with Fenske-Hall molecular orbital calculations and experimentally investigated by gas-phase photoelectron spectroscopy. A calculation for 1 (R = H) predicts that the highest occupied molecular orbital (HOMO) is metal-sulfur antibonding and largely sulfur in character. The observed HOMO ionization energies of 1 correlate with several chemical properties, including the rate of reaction of the thiolate ligand with alkyl halides. Solvent and substituent effects on the reaction rate favor a mechanism involving nucleophilic displacement of the halide by the coordinated thiolate ligand. The nucleophilicity of the coordinated thiolate ligand of 1 is related to the metal-sulfur d -p antibonding interactions.

Chloride substitution of [CpRu(dppf)Cl] with sulfur-containing ligands

“…The long Ru-S bond is due to the destabilizing filled-filled dp-pp orbital interaction between the p-type sulfur lone pair and the formally occupied metal dp orbitals of the Ru(II) low spin d 6 -centre, as sustantiated by FenskeHall molecular orbital calculations coupled with gas-phase photoelectron spectroscopy for CpFe thiophenolate complexes by Ashby et al [19].…”

Synthesis and Oxidation of Ruthenium Allyl Thioether Complexes Bearing Phosphite and Phosphonite Coligands [1]

“…The second steps of both paths apparently favor the same diastereoisomer. In the previously investigated series the rela tive configuration of the major diastereoisomer was in one case identified by X-ray crystallography as (R,R/S,S) [3], Compounds 7 and 8 do not provide any clear-cut spectroscopic handle from which the relative (7) or absolute (8 ) configurations of the two new stereocenters could be derived with certainty. The diastereoselectivity achieved in the oxidation of the bbpe complexes 6 a, b (eq (8 )) is similar to what we have found with the analogous (S,S)-CHIRAPHOS complexes [3].…”

“…Thiolate ligands are very strong a-and 7r-donors and as such are capable of stabilizing coordinatively unsaturated intermediates [8 ]. As a result, the substitution of adjacent ligands in low-valent transition metal complexes is greatly accelerated.…”

Methylation sites in tris(μ-thiolato)dimolybdenum(III) complexes

“…It should be observed that the monothioether complexes 4 are stable to further methyl addition. Finally, there is some evidence that the nucleophilicity of the sulfur atoms in the tris(thiolato)-bridged complexes 1 is restricted; for example, 1d does not react with soft alkylating agents (e.g., CH 3 I) though this reaction is generally observed for thiolate ligands bound to metal atoms which are in high oxidation states or are electron-deficient for other reasons [6].…”