Tricyclohexylphosphinecarbondisulphide seven-coordinate complexes of molybdenum(II) and tungsten(II)

Abstract The complexes [MI 2 (CO) 3 (NCMe) 2 ] (M = Mo or W) react with one equivalent of S 2 CPCy 3 in CH 2 Cl 2 to afford the new seven-coordinate complexes [MI 2 (CO) 3 (S 2 CPCy 3 )]. Reaction of [MI 2 (CO) 3 (NCMe) 2 ] (M = Mo or W), with two equivalents of S 2 CPCy 3 afford the new dicationic complexes [M(CO) 2 (S 2 CPCy 3 ) 2 ]2I in good yield. The dicationic nature [W(CO) 3 (S 2 CPCy 3 ) 2 ]2I was confirmed by the formation of the complex [W(CO) 3 (S 2 CPCy 3 ) 2 ][BPh 4 ] 2 by iodide exchange with Na[BPh 4 ]. Further reaction in situ of [M(CO) 3 (S 2 CPCy 3 ) 2 ]2I with one equivalent of S 2 CPCy 3 afforded the tris ligand complex [W(CO) 3 (S 2 CPCy 3 ) 3 ]2I. The reaction of [W(CO) 3 (S 2 CPCy 3 ) 3 ]2I with Na[BPh 4 ] in acetonitrile gave [W(CO) 3 (S 2 CPCy 3 ) 3 ][BPh 4 ] 2 , which confirmed the dicationic nature of [W(CO) 3 (S 2 CPCy 3 ) 3 ]2I. The mixed ligand complexes [MI(CO) 3 (PPh 3 )(S 2 CPCy 3 )]I (M = Mo or W) and [WI(CO) 3 L(S 2 CPCy 3 )]I (L = P(OPh) 3 , AsPh 3 or SbPh 3 ) were synthesised by reaction of [MI 2 (CO) 3 -(NCMe) 2 ] with an equimolar quantity of L in CH 2 Cl 2 followed by an in situ reaction with one equivalent of S 2 CPCy 3 . The cationic nature of [MI(CO) 3 (PPh 3 )(S 2 CPCy 3 )]I was confirmed by iodide exchange with Na[BF 4 ] to afford the complexes [MI(CO) 3 (PPh 3 )(S 2 CPCy 3 )][BF 4 ]. The reaction of two equivalents of [WI 2 (CO) 3 (NCMe)(PPh 3 )] with S 2 CPCy 3 afforded the ligand-bridged complex [W 2 I 4 (CO) 6 (PPh 3 ) 2 (μ-S 2 CPCy 3 )]. Treatment of [WI 2 (CO) 3 (NCMe) 2 ] with two equivalents of PPh 3 followed by an in situ reaction with one equivalent of S 2 CPCy 3 afforded the dicationic complex [W(CO) 3 (PPh 3 ) 2 (S 2 CPCy 3 )]2I. The ionic nature of the complex was confirmed by iodide exchange with Na[BPh 4 ] to give [W(CO) 3 (PPh 3 ) 2 (S 2 CPCy 3 )][BPh 4 ] 2 . Treatment of [W(CO) 3 (PPh 3 ) 2 (S 2 CPCy 3 )]2I with one further equivalent of S 2 CPCy 3 afforded the complex [W(CO) 3 (PPh 3 ) 2 (S 2 CPCy 3 )]2I. The low temperature 13 C NMR spectra (carbonyl region) of several-coordinate complexes are interpreted to suggest likely structures for these compounds.