1,4,7-Trithiacyclononane ([9]aneS3) and 2,5,8-trithia[9]orthocyclophane complexes of molybdenum(II) and tungsten(II): crystal structures of [WI(CO)3([9]aneS3)][BPh4] and [WI2(CO)3(NCMe)(PPh3)]

Abstract

Reaction of [MI₂(CO)₃(NCMe)₂](M = Mo or W) with a slight excess of 1,4,7-trithiacyclonoane ([9]aneS₃) in CH₂Cl₂ at room temperature gave the cationic complexes [MI(CO)₃([9]aneS₃)]I 1 and 2 in high yield. Treatment of 1 and 2 with an excess of Na[BPh₄] in methanol gave [MI(CO)₃([9]aneS₃)][BPh₄]3 and 4. The molecular structure of [WI(CO)₃([9]aneS₃)][BPh₄]4 has been determined by X-ray crystallography. It shows that the geometry around the tungsten centre is distorted capped octahedral with a capping carbonyl ligand. Room-temperature ¹³C NMR studies on complexes 1 and 2 indicate a unique CO ligand, demonstrating that their structures in solution are similar to that found for 4 in the solid state. Reaction of [MI₂(CO)₃(NCMe)L][M = Mo or W, L = PPh₃; M = W, L = P(OPh)₃] with an equimolar quantity of [9]aneS₃ gave the seven-co-ordinate cation/anion complexes [MI(CO)₂L([9]aneS₃)][MI₃(CO)₄]5–7. Treatment of [MI₂(CO)₃(NCMe)₂] with 1 equivalent of 2,5,8-trithia[9]orthocyclophane (ttoc) in CH₂Cl₂ at room temperature gave the dicarbonylmolybdenum complex [MoI₂(CO)₂(ttoc)]8 or the seven-co-ordinate cation/anion tungsten complex [WI(CO)₃(ttoc)][WI₃(CO)₄]9. Reaction of [MI₂(CO)₃(NCMe)L] with an equimolar amount of ttoc gave [MI(CO)₂L(ttoc)][MI₃(CO)₄]10–12. The complex [WI₂(CO)₃(NCMe)(PPh₃)] was also shown to have a distorted capped-octahedral geometry by X-ray crystallography.