REACTIONS OF BIS(IMINOPHOSPHORANYL)METHANES WITH CHLORO-BRIDGED RHODIUM OR IRIDIUM DIMERS GIVING COMPLEXES IN WHICH THE LIGAND IS COORDINATED EITHER AS A SIGMA-N, SIGMA-N' OR AS A SIGMA-N, SIGMA-C CHELATE - X-RAY CRYSTAL-STRUCTURE OF THE SIGMA-N, SIGMA-N' RH(I) COMPLEX [RH((4-CH3-C6H4-N=PPH2)2CH2)(COD)]PF6

Bridge splitting reactions of [ML2Cl2]2 (M = Rh, Ir; L2 = COD, NBD; L = CO) with bis-iminophosphoranylmethanes CH2(PPh2 = NR)2 (bipm, I) lead to Rh(I) and Ir(I) complexes with N,N' as well as N,C bidentate coordinated bipm: [ML2{(4-R'-C6H4-N = PPh2)2CH2}]+X- (II) and [ML2{(4-R'-C6H4-NH-PPh2)CH(PPh2 = N-C6H4-R'-4)}]+X- (III; R' = CH3, NO2, OCH3; X = Cl, MCl2L2, BF4, PF6). The ratio II:III depends on the metal, the bipm ligand I, the solvent and the presence of silver(I) or sodium salts. In the N,C coordinated bipm, a tautomeric 1,3-H shift from carbon to the pendant nitrogen atom has taken place. The X-ray crystal structure of [Rh{(4-CH3-C6H4-N = PPh2)2CH2}(COD)]PF6 has been solved. Space group P2(1)/c, monoclinic, a = 21.832(9), b = 22.349(6), c = 12.001(6) angstrom, beta = 100.28(3)-degrees, Z = 4. Refinement of 4071 observed reflections converged to R = 0.087. The structure comprises a distorted square planar Rh(I) environment where the coordination positions are taken by COD and the two nitrogen atoms of the bipm ligand. The six-membered Rh-N = P-C-P = N-Rh metallacycle has a distorted boat conformation. Synthesis and spectroscopic data of the pure complexes II and III are described. The formation of the complexes and the influence of the reaction parameters on the ratio II:III are discussed.