TRIPHENYLPHOSPHINEOXIDE AND TRIPHENYLPHOSPHINESULFIDE 7-COORDINATE COMPLEXES OF MOLYBDENUM(II) AND TUNGSTEN(II)

The complexes [MI2(CO)3(NCMe)2] (MMo or W) react with one equivalent of OPPh3 in CH2Cl2 at room temperature to rapidly afford the iodo-bridged dimers [M(μ-I)I(CO)3(OPPh3)]2 in good yield. By contrast reaction of equimolar quantities of SPPh3 and [MI2(CO)3(NCMe)2] react in CH2Cl2 at room temperature to give the monoacetonitrile monomers [MI2(CO)3(NCMe)(SPPh3)]. The monomers [MI2(CO)3(NCMe)(SPPh3)] dimerise very slowly on stirring at room temperature in CH2Cl2 for 24 h to eventually give the iodo-bridged dimers [M(μ-I)I(CO)3(SPPh3)]2. The molybdenum iodo-bridged compound [Mo(μ-I)I(CO)3(OPPh3)]2 reacts with two equivalents of L (LPPh3, AsPh3 or P(OPh)3) to rapidly give the bridged cleaved products [MoI2(CO)3L(OPPh3)]. The monoacetonitrile complexes [MI2(CO)3(NCMe)(SPPh3)] react in situ with an equimolar quantity of [NBun4]I in CH2Cl2 at room temperature to give the expected anionic compounds [NBun4][MI3(CO)3(SPPh3)] in good yield. The bis- acetonitrile compounds [MI2(CO)3(NCMe)2] react with two equivalents of L (LOPPh3 or SPPh3) in CH2Cl2 to afford the bis-ligand compounds [MI2- (CO)3L2] in high yield. However, one equivalent of L (LOPPh3 or SPPh3) reacts with [MI2(CO)3L2] to give the monocationic complexes [MI(CO)3L3]I. The ionic nature of these complexes was confirmed by the formulation of the complex [MoI(CO)3- (SPPh3)3][BPh4] by iodide exchange with Na[BPh4]. The reaction of [MI2(CO)3L2] with two equivalents of L (LOPPh3 (for MW only) or SPPh3) give the dicationic compounds [M(CO)3L4]2I. The bis- tetraphenylborate complex [Mo(CO)3(SPPh3)4]- [BPh4]2 was also prepared in the normal manner. Three equivalents of OPPh3 react with [MI2(CO)3- (OPPh3)2] to give the dicarbonyl compounds [M(CO)2(OPPh3)5]2I in high yield. The mixed ligand complexes [MI2(CO)3L′L] (MMo or W; LOPPh3 or SPPh3; L′PPh3, AsPh3 or SbPh3) were synthesized by reaction of [MI2(CO)3(NCMe)2] with an equimolar quantity of L′ in CH2Cl2, followed by an in situ reaction with one equivalent of L. The triphenylphosphine complex [MoI2(CO)3(PPh3)- (OPPh3)] on stirring in CH2Cl2 for 18 h gave the anionic complex [PPh3H][MoI3(CO)3(OPPh3)]. Low temperature 13C NMR spectra (carbonyl region) for several seven-coordinate complexes are interpreted to suggest structures for these compounds. © 1990.