SYNTHESIS, CHARACTERIZATION, AND REACTIONS OF PLATINUM AND RHODIUM COMPLEXES OF THE HYBRID PHOSPHORUS-NITROGEN LIGAND 4-CH3C6H4C[N(SIME3)](NPPH2) - X-RAY STRUCTURES OF [ML2(PPH2NHC(4-CH3C6H4)NH)]X (M = PT, X = CL - M = RH, X = BF4)

The reaction of 4-CH3C6H4C[N(SiMe3)2](NPPh2) with [Pt(PEt3)Cl2]2 or [Rh(cod)Cl]2 in a 2:1 molar ratio in THF produces the monodentate complexes trans-Pt(PEt3)[PPh2NC(4-CH3C6H4)N(SiMe3)2]Cl2 (4a) and Rh(cod)[PPh2-NC(4-CH3C6H4)N(SiMe3)2]Cl (4b), which were characterized by H-1 and P-31 NMR spectroscopy. The reaction of 4a with PhSeCl in a 1:2 molar ratio yields Pt(PEt3)Cl [PPh2NHC(4-CH3C6H4)NH] Cl (5), which was identified by H-1 and P-31 NMR spectroscopy and by X-ray crystallography. This complex crystallizes in the space group P1BAR with a = 11.840(1) angstrom, b = 14.523(8) angstrom, c = 10.081(3) angstrom, alpha = 107.93(3)degrees, beta = 90.00(2)degrees, gamma = 87.60(2)degrees, Z = 2, and R = 0.044 for 2950 observed reflections. The PPh2NHC(4-CH3C6H4)NH ligand in 5 is chelated via phosphorus and nitrogen to platinum with the PPh2 and PEt3 groups in cis positions and hydrogen-bonding [d(H(N)-Cl) = 2.20 angstrom] between the NH group attached to phosphorus and the chloride counterion. By contrast, the H-1-N-15 HMQC spectra of 5 indicate that in solution the other NH group (delta(H-1) = 12.73 ppm) is involved in strong hydrogen-bonding with the chloride counterion. The decomposition of 4a in boiling THF also yields 5. Possible pathways for the formation of 5 by these two different routes are discussed. The reaction of 4-CH3C6H4C[N(SiMe3)2]-(NPPh2) with [Rh(cod)Cl]2 in acetone in the presence of NaBF4 produces [Rh(cod)(PPh2NHC(4-CH3C6H4)-NH)]BF4 (8), which was characterized by H-1 and P-31 NMR spectra and by X-ray crystallography. The crystals of 8 are triclinic, space group P1BAR, with a = 13.844(6) angstrom, b = 14.236(7) angstrom, c = 9.156(5) angstrom, alpha = 99.08(4)degrees, beta = 105.08(4)degrees, gamma = 68.84(3)degrees Z - 2, and R = 0.074 for 2929 observed reflections. The PPb2NHC(4-CH3C6H4)NH ligand in 8 is chelated to rhodium in a fashion similar to that observed for 5. The reaction of 4-CH3C6H4C[N(SiMe3)2](NPPh2) With [Rh(CO)2Cl]2 in a 2:1 molar ratio in THF produces Rh(CO)[PPh2NHC(4-CH3C5H4)-NH]Cl identified by H-1, C-13, and P-31 NMR and IR spectroscopic data.