Controlling the Number of Metal Sites to Which a Polytertiary Phosphine Coordinates in Tungsten Carbonyls

Judiciously selected coordinated fragments of Ph2PCH2CH2PPhCH2-CH2PPh2 [(OC)5WPPh2H, (OC)5WPPh2CH=CH2 and (OC)5WPPh(CH=CH2)2] were used to construct its five possible nonchelated pentacarbonyltungsten complexes. These are the trimetallic (OC)5WPPh[CH2CH2PPh2W(CO)5]2 and the two pairs of constitutional isomers, (OC)5WPPh[CH2CH2PPh2]2 and (OC)5WPPh2CH2CH2PPhCH2CH2PPh2, and PPh[CH2CH2PPh2W(CO)5]2 and (OC)5WPPh2CH2CH2PPh[W(CO)5]CH2CH2PPh2. Their syntheses, based on free radical and base catalyzed addition reactions, demonstrate a successful approach to ligation control of a polydentate phosphorus ligand. The reactions used to synthesize these complexes are as follows […] The new complexes were characterized structurally by phosphorus-31 nuclear magnetic resonance and infrared spectroscopy and their purity established with elemental analyses