Reactions of the novel Schiff's base 2-(3-nitrobenzylidene)-benzimidazole (3a) with Rh, Ir and Pt. X-ray crystal structure of (CF3SO3)

Article abstract of DOI:10.1016/0022-328X(88)83153-X

The chemistry of the Schiff's base 2-(3-nitrobenzylidene)benzimidazole (3a), with rhodium(I) is described, and the molecular structure of the cationic complex (CF3SO3) (4b) is reported.The compex has a distorted square planar geometry with the benzimidazole imine-N coordinated; relevant bond distances (Angstroem) and angles (deg) are: Rh-N(1), 2.100(6), Rh-N(6), 2.095(6), Rh-C(16), 2.117(11), Rh-C(17), 2.131(9), Rh-C(20), 2.131(9), Rh-C(21), 2.112(9) Angstroem; N(1)-Rh-N(6), 88.0(2), N(1)-Rh-C(16), 89.5(3), N(1)-Rh-C(17), 92.6(3), N(6)-Rh-C(20), 90.6(3), N(6)-Rh-C(21), 91.7(3) deg.Ligand 3a reacts with 2 (M = Rh, Ir) in the presence of PPh3 to afford rhodium(III) and iridium(III) complexes in which the imine C-H bond has oxidatively added.This type of addition also takes place whith 2-(4-methyl-benzylidene)benzimidazole and several derivatives are reported.Ligand 3a when coordinated to platinum(II) in trans-PtCl2(3a)(PhCH=CH2) does not give rise to Pt <- H-C interactions, in contrast to 2-(3-nitrobenzylidene)3-methylpyridine (2).Reasons for this are suggested, and a steric boundary condition is proposed for this weak Pt <- H-C interaction, the 5- and 6-methyl analogs of 2 being used as models. 103Rh NMR data for two rhodium(III) complexes are reported.