Inorganic Chemistry, Vol.47, No.7, 2608-2612, 2008
Migratory insertion, of the R2P group into a nitrogen-nitrogen bond - A novel type of rearrangement in phosphorus-nitrogen ligand chemistry. 3. The rearrangement of triphosphinohydrazide ligand-N(PPh2)-N(PPh2)(2) to triphosphazenide anion {[(Ph2P-N](2)PPh2}(-) the coordination sphere of divalent cobalt and nickel
Hydrazine dihydrochloride reacts with 3 equiv of Ph2PCl in tetrahydrofuran in the presence of triethylamine to give tris(diphenylphosphino)hydrazine (1) in 70% yield. Each nitrogen atom in 1 has a trigonal-planar environment according to X-ray analysis. Thermolysis of 1 at 130 degrees C results in the formation of two products: bis(diphenylphosphino)amine and octaphenylcyclotetraphosphazene. The interaction of free ligand 1 with NiBr2 affords a simple adduct [(Ph2P)(2)N-NH-PPh2]NiBr2, while its anionic (hydrazide) form undergoes rearrangement in a coordination sphere of divalent cobalt and nickel involving migratory insertion of the Ph2P group into a nitrogen-nitrogen bond. The reaction of 1 with cobalt bis(trimethylsilyl)amide, [(Me3Si)(2)N](2)Co, yields the complex of phosphazenide-type (Me3Si)(2)N-Co[(Ph2PN)(2)PPh2] (2) in 86% yield. A similar reaction of 1 with nikelocene proceeds with substitution of one Cp ring to form durable 18-electron complex CpNi[(Ph2PN)(2)PPh2] (3).