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

Abstract

Attempts at methylating cis-[Mo 2Cp 2(μ-SMe) 3L 2](BF 4) [Cp = η 5-C 5H 5; L = CO ( 1a) CNxyl ( 1b), CNBu t ( 1c), NCMe ( 1d)] with methyl triflate gave the corresponding thioether-bridged cations [Mo 2Cp 2(μ-SMe) 2(μ-SMe 2)L 2] 2+ ( 4 2+), except in the case of 1a which did not react at room temperature. The electronic properties of the ancillary ligands L thus have a crucial influence on the course of this reaction. The dimeric compounds [Mo 2Cp 2(μ-SMe) 3(CNBu t )(CN)] ( 2) and [Mo 2Cp 2(μ-SMe) 3{μ-η 1-N C(CH 3)CH 2CN}] ( 3), which potentially offer the alternatives of S- or N-methylation, reacted with methylating agents to give mainly the S-methylated derivatives 5 and 7. Only in the case of the nucleophilic reactant 2 was N-methylation also observed and isomer 6 was obtained as a minor product together with 5. New complexes have been completely characterised by multinuclear NMR, IR and elemental analysis, supplemented for 5 by X-ray diffraction study at 100 K.