SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF 2 MOLYBDENUM CARBONYL-COMPLEXES CONTAINING DITHIOCARBAMATO LIGANDS DERIVED FROM PYRROLIDINE AND PIPERIDINE

Reaction of [Mo(pip)(2)(CO)(4)] (pip = piperidine) with (S, S)(-) in a cetonitrile gives readily [Mo(eta(2)-(S, S))(CO)(4)](-), isolated as [ PPN][Mo(eta(2)-(S, S))(CO)(4)] (PPN+ = bis(triphenylphosphine)iminium; (S, S)(-) = pyrrolidine- (1) or piperidine-1-carbodithioato (2)). The two compounds have been characterized by elemental analysis, IR, nucl ear magnetic resonance and X-ray crystallography. 1: monoclinic, P2(1) /n; a = 16.207(5), b = 12.804(3) Angstrom, c = 20.398(4) Angstrom; bet a = 91.02(2)degrees; V = 4232(2) Angstrom(3), Z = 4; R = 0.034, R(w) = 0.037 based on 4989 reflections with I> 3.0 sigma(I). 2: monoclinic, P2(1)/n; a = 14.148(4) Angstrom, b = 13.646(5) Angstrom, c = 27,.535(8 ) Angstrom; beta = 95.92(3)degrees; V = 4327(3) Angstrom(3), Z = 4; R = 0.054, R(w) = 0.041 based on 2048 reflections with I> 2.0 sigma(I). No appreciably modified ligand structure is found in response to the d ifferent pK(a) of the amine used to form the specific (S, S)(-) in the compounds. This feature is rationalized by the electron-withdrawing e ffect of the metal carbonyl fragment, leading to the observed similari ty in both the C-O stretching and the Mo-C-O distances.