Diisothiocyanatophenylphosphine—C 6H 5P(NCS) 2—a versatile chelating agent towards transition metal ions

Abstract

The title reagent, an unstable P III derivative, affords table compounds via chelation with metal ions. With PdCl 2 the diamagnetic complex [Pd(L)Cl]Cl ( 1) (L = C 6H 5P(NCS) 2), with square planar geometry was obtained. Reactions of NiCl 2 and PdCl 2 with the reagent in presence of Zn powder have yielded M(L) 2, M = Pd ( 2), Ni ( 3), with metals in the zero valent state. Analogous redox reaction with Ni(Ph 3P) 2Cl 2 has provided two products. A good yield of a red diamagnetic compound [Ni 2(Ph 3P) 4(L) 2]Cl 2 ( 4a) and spectral data indicate that it is a ligand bridged dimer processing NiNi bonds with d 9 configuration of Ni ions in which both the Ni I ions are five coordinate. The second minor product is a yellow solid [Ni 2(Ph 3P) 2(L) 2]Cl 2 ( 4b), which is also a ligand bridged, diamagnetic dimer due to NiNi bonding but with tetracoordinate Ni I ions. Reaction of Ru(Ph 3P) 3Cl 2 with the reagent affords [Ru(Ph 3P)(L)Cl]Cl ( 5) along with 2 mol equivalent of free ancillary ligand Ph 3P, as released in the solution. Present investigations are consistent with a d 6 configuration of the metal ion in ( 5) having a trigonal bipyramidal array of ligands around the Ru II ion. Reaction of (η 5-C 5H 5) 2TiCl 2 with the reagent produces red (η 5-C 5H 5) 2Ti(NCS) 2 ( 6a) (major) and yellow (minor) (η 5-C 5H 5) 2Ti(L)Cl ( 6b), and the latter is a Ti III species. Metathetic reaction of titanocene dichloride with AgSCN ha produced a good yield of a red solid ( 6a *) found to be chemically identical with ( 6a).