2,2′:6′,2″-Terpyridine complexes of molybdenum(II) and tungsten(II). X-ray crystal structures of [MoI(CO)(terpy)(η2-PhC2Ph)]I and [WI(terpy)(η2-PhC2Ph)2]I·CDCl3

Equimolar quantities of [MI2(CO)3(NCMe)2] (M=Mo or W) and terpy (terpy=2,2′:6′,2″-terpyridine) react in CH2Cl2 at room temperature to give the cationic complexes [MI(CO)3(terpy)]I (1 and 2) in high yield. Treatment of [MoCl(GeCl3)(CO)3(NCMe)(PPh3)] with one equivalent of terpy affords [Mo(GeCl3)(CO)2(PPh3)(terpy)]Cl (3) in good yield. Reaction of [MI2(CO)(NCMe)(η2-RC2R)2](M=Mo, W; R=Ph; for M=W only, R=Me) with an equimolar quantity of terpy in CH2Cl2 at room temperature gives the cationic complexes [MI(CO)(terpy)(η2-RC2R)]I (4 and 5) or the crystallographically characterised cationic complex [WI(terpy)(η2-PhC2Ph)2]I (6). Equimolar quantities of [WI(CO)(terpy)(η2-MeC2Me)]I(5) and Na[BPh4] react to give the anion-exchanged product, [WI(CO)(terpy)(η2-MeC2Me)][BPh4] (7). The X-ray crystal structure of [MoI(CO)(terpy)(η2-PhC2Ph)]I shows the three nitrogen atoms of the terpy bonded in the equatorial plane of an octahedron together with the carbonyl group. The iodo and diphenylacetylene ligands are mutually trans- to each other in the axial positions. The structure of [WI(terpy)(η2-PhC2Ph)2]I·CDCl3 (6) has a distorted octahedral geometry, with the three nitrogen atoms of the terpy ligand in a mer-configuration, with two cis-and parallel diphenylacetylene ligands and an iodo group occupying the other three mer-sites.