Synthesis and characterisation of monomeric and dimeric 2-substituted η3-bonded butadienyl complexes of molybdenum(II)

Abstract

Addition of excess thiol RSH ( R = Et, nPr, iPr, nBu or iBu ) to solutions of [MoCl(CO) 2( η 3-CH 2C(COCl)C=CH 2)(phen)] ( 1) (phen = 1,10-phenanthroline) gave good yields of the complexes [MoCl(CO) 2( η 3-CH 2C(COSR)C=CH 2)(phen)], containing a 2-substituted butadienyl ligand. On reaction of 1 with 1,2-ethanedithiol in 2:1 molar ratio under basic conditions, dimeric complexes were obtained containing two metal centres bridged by a pair of 2-substituted butadienyl groups linked by the dithiol unit. Analogous dimeric complexes containing linked amido η 3-butadienyl groups were isolated from a similar 2:1 reaction of 1 and diamines RHN(CH 2) 2NHR (R  H or Me). However, reactions involving 1 and mixed bifunctional reactants HA(CH 2) 2BH (A = NH, B = O, S or A = O, B = S) under the same conditions gave monomeric complexes exclusively, the less electronegative atom of the donor pair remaining unreacted.