Pentacoordinated cationic rhodium(I) and iridium(I) organocomplexes with α-diimine ligands derived from glyoxal:: crystal structure of [Rh(norbornadiene) (glyoxalbis(4-dimethylamino-anil))-(PPh3)] BF4•1/2CH2Cl2

[{M(L-2)Cl}(2)] (M = Rh, L-2 = norbornadiene (NBD))z; M = Ir, L-2 = 1,5-cyclooctadiene (COD) react in acetone solution with PPh3, AgBF4 and alpha-diimines derived from glyoxal RN:C(H)C(H):NR(LL) to give pentacoordinated [M(L-2) (LL) (PPh3)] BF4 complexes. The molecular structure of [Rh(NBD) (GAA) (PPh3)]BF4. 1/2CH(2)Cl(2) (GAA= glyoxalbis(4-dimethylanlino-anil)) was determined by X-ray diffraction study. The cation is best described as having slightly distorted trigonal bipyramidal geometry with the equatorial positions occupied by the diimine and one of the olefinic bonds of NBD and the other olefinic bond and the PPh3 in axial positions. [M(L-2)(GCH)(PPh3)]BF4 (GCH = glyoxalbis(cyclohexylimine)) react with carbon monoxide to give tetracoordinated [ Rh(CO) (GCH) (PPh3)] BF4 when M = Rh or pentacoordinated [Ir(CO)(2)(GCH)(PPh3)]BF4 when M=Ir. The reaction of trans-M(OClO3)(CO) (PPh3)(2) with GCH, GAA or GHA ( GHA = glyoxalbis (4-hydroxy-anil)) leads to displacement of the covalently bonded perchlorate group by a-diimine, giving pentacoordinated monocarbonylated [M(CO)(LL) (PPh3)(2)] ClO4. (C) 1998 Elsevier Science S.A. All rights reserved.