Synthesis and, structural characterization of two molybdenum carbonyl complexes containing dithiocarbamato ligands derived from pyrrolidine and piperidine

Reaction of [Mo(pip),(CO),] (pip = piperidine) with (S, S)in acetonitrile gives readily [Mdq*-(S, SlXCO)J, isolated as [PPNl[Mo(n*-(S, S))(CO),] (PPN+= bis(triphenylphosphine)iminium; (S, S)-= pyrrolidine(1) or piperidine-1-carbodithioato (2)). The two compounds have been characterized by ejemental analysisd IR, nuclear magnetic resonance and X-ray crystallography. 1: monoclinic, P2,/n; a = 16.207(S), b = 12.804(3) A, c = 20.398(4) A, B = 91.02(zF, V= 4232(2) $, Z = 4; R = 0.034, R, = 0.037 based on 4989 reflections with I > 3.00(I). 2: monoclinic, P2,/n; a = 14.148(4) A, b = 13X%6(5) A, c = 22.535(8) A; B = 95.92(3)“; V= 4327(3) i3, Z = 4; R = 0.054, R, = 0.041 based on 2048 reflections with I > 2.00(I). No appreciably modified ligand structure is found in response to the different pK, of the amine used to form the specific (S, S)in the compounds. This feature is rationalized by the electron-withdrawing effect of the metal carbonyl fragment, leading to the observed similarity in both the C-O stretching and the MO-C-O distances.