HALOCARBONYL ALKYNE COMPLEXES OF MOLYBDENUM(II) - CRYSTAL-STRUCTURES OF [MOI2(CO)(NCME)(ETA(2)-RC2R)(2)] (R = ME AND PH) AND [MOI2(CO)(5,6-ME-2-1,10-PHEN)(ETA(2)-PHC2PH)]

Reaction of [MoXX'(CO)(3)(NCMe)(2)] with RC2R' in CH2Cl2 at room tempe rature gave the bis (alkyne) complexes [MoXX'(CO)(NCMe)(eta(2)-RC2R')( 2)] (X = X' = I, R = R' = Me; X = X' = Br, R = R' = Me, Ph; X' = I, X = Cl, Br, R = R' = Me, Ph) (1-->7) in high yield. The molecular struct ures of [MoI2(CO)(NCMe) (eta(2)-RC2R)(2)] (R = Me, Ph) have been deter mined by X-ray crystallography. The two structures are very similar, w ith the two alkyne ligands cis- and parallel to each other and trans- to the two iodo ligands. The carbon monoxide and acetonitrile ligands occupy the two axial sites. Treatment of [MoI2(CO)(NCMe)(eta(2)-RC2Ph) (2)] with an equimolar amount of (LL)-L-boolean AND {for R = Ph, (LL)- L-boolean AND = 5,6-Me-2-1,10-phen, Ph2P(CH2)(2)PPh2; for R = Me, (LL) -L-boolean AND = 2,2'-bipy, Ph2P(CH2)(n)PPh2, n = 1, 3, 4} yielded the mono(alkyne) complexes [MoI2(CO)((LL)-L-boolean AND)(eta(2)-RC2Ph)] ( 8-->13), which for (LL)-L-boolean AND = 5,6-Me-2-1,10-phen, R = Ph (8) was crystallogaphically characterised. The geometry around the molybd enum centre is essentially octahedral, with the phenanthroline ligand trans- to a carbonyl and an iodide ligand, with the alkyne and other i odide group in the axial sites. Reaction of [MoI2(CO)(NCMe)(eta(2)-MeC 2Ph)(2)] with two equivalents of NaS2CNMe2 in CH2Cl2 gave [Mo(CO)(S2CN Me2)(2) (eta(2)-MeC2Ph)] (14). (C) 1998 Elsevier Science Ltd. All righ ts reserved.