Diosmium and dirhodium compounds containing a cisoid arrangement of 2-diphenylphosphinopyridine bridges

Abstract

Two new compounds with a novel cisoid arrangement of bridging 2-diphenylphosphinopyridine (Ph 2Ppy) have been synthesized. They have been prepared from the tetraacetate compounds and show varying degrees of substitution of the carboxylate ligands. Os 2(O 2CCH 3)(Ph 2Ppy) 2Cl 4 ( 1) has been isolated from the reaction of Ph 2Ppy with Os 2(O 2CCH 3) 4Cl 2. It has been obtained in two crystalline forms: as a dichloromethane adduct ( 1a) and as an acetone adduct ( 1b). Compound 1a crystallizes in the monoclinic space group P2 1/ n with a= 10.496(3), b=20.688(5), c=18.440(5) Å, β= 91.62(2)°, V=4003(3) Å 3 and Z=4. Compound 1b crystallizes in the monoclinic space group P2 1/ c with a=18.977(5), b=10.469(2), c=20.737(6)Å, β=92.36(2)°, V=4116(3) Å 3 and Z=4. The molecule of 1 contains a cisoid arrangement of the two Ph 2Ppy ligands arranged in a head-to-tail fashion, one bridging acetate ion and four chloride ions. The metal-metal distance is 2.395(1)Å in 1a and 2.388(1) Å in 1b and the formal bond order is 2.5. Rh 2(O 2CCH 3) 2(Ph 2Ppy) 2Cl 2 ( 2) has been isolated from the reaction of Rh 2(O 2CCH 3) 4(MeOH) 2 with Ph 2Ppy in toluene in the presence of LiCl. Compound 2 crystallizes in the tetragonal space group P 4 2 1 c with a= b=22.203(3), c=17.049(2) Å, V=8404(2) Å 3 and Z=8. The two Ph 2Ppy ligands are arranged in a cisoid fashion, along with two bridging acetate groups and two axial chloride ions. The rhodium- rhodium distance is 2.518(1) Å.