93565-26-5Relevant academic research and scientific papers
Synthesis and structural characterization of rhodium(I) and iridium(I) complexes of the asymmetric tetradentate PPNN ligand 2,2′-bis[[o-(diphenylphosphino)benzylidene]amino]-6,6′- dimethylbiphenyl
Marxen, Tricia L.,Johnson, Brian J.,Nilsson, Per V.,Pignolet, Louis H.
, p. 4663 - 4670 (2008/10/08)
The new asymmetric ligand 2,2′-bis[[o(diphenylphosphino)benzylidene]amino]-6,6′- dimethylbiphenyl, PPNN, was synthesized by the Schiff base reaction of o-(diphenylphosphino)benzaldehyde with 2,2′-dimethyl-6,6′-diaminobiphenyl. The d and l optical isomers of PPNN were also synthesized by the above reaction using the resolved enantiomers of 2,2′-dimethyl-6,6′-diaminobiphenyl. Specific and molecular rotations ([α]25D, [M]25D (CHCl3)) for d-PPNN and l-PPNN were +198, 1493° and -193, -1457°, respectively. Rh(I) and Ir(I) complexes of PPNN were synthesized by the reactions of PPNN with [Rh(1,5-cyclooctadiene)Cl]2 and Ir(PPh3)2(N2)Cl, respectively, using CH2Cl2 as solvent. Both complexes were isolated in good yield as BPh4 salts. The single-crystal X-ray structures of racemic [Rh(PPNN)]BPh4 and [Ir(PPNN)]BPh4 were determined. The two compounds are essentially isostructural. Crystal parameters for Rh: P1, a = 13.473 (2) A?, b = 13.506 (2) A?, c = 17.424 (3) A?, α = 100.20 (1)°, β = 98.17 (1)°, γ = 91.41 (1)°, Z = 2, R (Rw) = 0.034 (0.047) for 6168 observations [Fo2 ≥ 3σ(Fo2)]. Crystal parameters for Ir: P1, a = 13.48 (1) A?, b = 13.551 (3) A?, c = 17.438 (8) A, α = 100.28 (3)°, β = 98.00 (5)°, γ = 91.38 (4)°, Z = 2, R (Rw) = 0.055 (0.064) for 4483 observations [Fo2 ≥ 2σ(Fo2)]. Both compounds have approximately square-planar P2N2 coordination core geometries with average Rh-P and Ir-P distances of 2.222 (1) and 2.244 (3) A? and with average Rh-N and Ir-N distances of 2.106 (3) and 2.09 (1) A?, respectively. The PPNN ligand is tetradentate in both complexes, and the twisted substituted biphenyl group imposes an asymmetry on the entire complex. The reactions of these complexes with CO and H2 have been studied.
