DIISOTHIOCYANATOPHENYLPHOSPHINE-C6H5P(NCS)2 - A VERSATILE CHELATING AGENT TOWARDS TRANSITION-METAL IONS

The title reagent, an unstable P(III) derivative, affords stable compo unds via chelation with metal ions. With PdCl2 the diamagnetic complex [Pd(L)Cl]Cl (1) (L = C6H5P(NCS)2), with square planar geometry was ob tained. Reactions of NiCl2 and PdCl2 with the reagent in presence of Z n powder have yielded M(L)2, M = Pd (2), Ni (3), with metals in the ze ro valent state. Analogous redox reaction with Ni(Ph3P)2Cl2 has provid ed two products. A good yield of a red diamagnetic compound [Ni2(Ph3P) 4(L)2]Cl2 (4a) and spectral data indicate that it is a ligand bridged dimer possessing Ni-Ni bonds with d9 configuration of Ni ions in which both the Ni(I) ions are five coordinate. The second minor product is a yellow solid [Ni2(Ph3P)2(L)2]Cl2 (4b), which is also a ligand bridge d, diamagnetic dimer due to Ni-Ni bonding but with tetracoordinate Ni( I) ions. Reaction of Ru(Ph3P)3Cl2 with the reagent affords [Ru(Ph3P)(L )Cl]Cl (5) along with 2 mol equivalent of free ancillary ligand Ph3P, as released in the solution. Present investigations are consistent wit h a d6 configuration of the metal ion in (5) having a trigonal bipyram idal array of ligands around the Ru(II) ion. Reaction of (eta5-C5H5)2T iCl2 with the reagent produces red (eta5-C5H5)2Ti(NCS)2 (6a) (major) a nd yellow (minor) (eta5-C5H5)2Ti(L)Cl (6b), and the latter is a Ti(III ) species. Metathetic reaction of titanocene dichloride with AgSCN has produced a good yield of a red solid (6a) found to be chemically ide ntical with (6a).