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

Attempts at methylating cis-[MO2CP2(mu-SMe)(3)L-2](BF4) [CP = eta(5)-C5H5; L = CO (1a) CNxyl (1b), CNBu'(1c), NCMe (1d)] with methyl triflate gave the corresponding thioether-bridged cations [Mo2CP2(mu-SMC)(2)(v-SMe2)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 [Mo2CP2(mu-SMe)(3)(CNBu’)(CN)] (2) and [Mo2CP2(mu-SMe)(3){mu-eta(1)-N=C(CH3)CH2CN}] (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. (c) 2005 Elsevier B.V. All rights reserved.