REACTIONS OF RH-BIS(IMINOPHOSPHORANYL)METHANIDE AND IR-BIS(IMINOPHOSPHORANYL)METHANIDE COMPOUNDS WITH ELECTROPHILES - A TRAPPED CATION-ANION COMPLEX IN THE OXIDATIVE ADDITION OF IODINE TO A D(8) METAL CENTER AND X-RAY CRYSTAL-STRUCTURE OF [IRI(CW(PPH(2)=N-C6H4CH3-4)(2))(COD)]I, CONTAINING 2 FUSED 4-MEMBERED METALLACYCLES

Reaction of square planar M{CH(PPh(2)=N-C6H4-CH3-4)(2)(COD)] (1a: M=Rh; 1b: M=Ir), in which the bis-iminophosphoranylmethanide ligand is bidentate N,C-coordinated, with I-2, MeI and MeOSO(2)CF(3) yields products resulting from metal or ligand (N atom) centred reactivity. Complexes 1a and 1b react with MeI and MeOSO(2)CF(3) to yield mainly cationic N-methyl or N,N'-dimethy] derivatives. The reaction of 1b with I-2 results in the selective formation of the hexacoordinate Ir(III) complex (OC-6-43)-[Ir(I)sigma-N,sigma-N',sigma-C-{CH(PPh(2) = N-C6H4-CH3-4)(2)}(eta(2),eta(2)-COD)]I-+(-) (4). The molecular structure of 4 has been determined by an X-ray crystal structure study; it crystallizes in space group P2(1)/c with a = 21.040(2), b = 18.399(2), c = 26.075(3) Angstrom and beta = 102.33(2)degrees. A total of 5243 reflections (I > 2.5 sigma(I)) has been used in the refinement which converged, after including a model for observed disorder, to R = 0.061 (R(W) = 0.084). In the cationic part of 4 the N,N',C ligand is facially tridentate coordinated to Ir, thus forming a [2.2.0]-bicyclohexane structure containing an Ir, a C, two P and two N atoms. Iodine is in hans position to the methanide carbon atom. Compound 4 represents a trapped cation-anion complex and may be regarded as a model of an intermediate in the polar oxidative addition of I-2 to d(8) transition metal compounds. Instead of coordinating the second iodine atom, stabilization of 4 is achieved by virtue of the adaptation of the bis(iminophosphoranyl)methanide ligand by coordination of the pendant N atom.