Synthesis, reactivity, and X-ray crystal structure of [Rh{C6H4N(O)O-2}(η-C5Me5)Cl]

Abstract

Reaction of [{Rh(η-C₅Me₅)Cl₂}₂] with [Hg(C₆H₄NO₂-2)₂](1/1) or [Hg(C₆H₄NO₂-2)Cl](1/2) in the presence of an excess of [NMe₄]Cl gives [[graphic omitted]-2}(η-C₅Me₅)Cl]. This compound reacts with AgClO₄ giving solutions from which, after addition of the corresponding ligands, the cationic complexes [[graphic omitted]-2}(η-C₅Me₅)(PPh₃)]ClO₄, [[graphic omitted]-2}(η-C₅Me₅)(py)]ClO₄(py = pyridine), [Rh(C₆H₄NO₂-2)(η-C₅Me₅)(bipy)]ClO₄(bipy = 2,2′-bipyridyl) can be obtained. The crystal structure of [[graphic omitted]-2}(η-C₅Me₅)Cl] has been determined by an X-ray diffraction study. Crystals are orthorhombic, space group Pbca, with a= 14.574 2(5), b= 14.917 8(6), c= 14.678 2(6)Å, and Z= 8. The molecule exhibits a pseudo-octahedral geometry around the rhodium atom with the C₆H₄(O)O-2 group acting as a chelating ligand, bonded to the metal through a carbon atom of the phenyl ring [Rh–C(1) 2.023(3)Å] and an oxygen atom of the nitro group [Rh–O(1) 2.142(3)Å]. The co-ordination of the nitro group causes a lengthening of the N–O(Rh) bond distance [N–O(1) 1.260(4)Å] compared with the unco-ordinated N–O bond length [1.224(4)Å]. Infrared data indicate that the aryl ligand co-ordinates in the same way in the complexes [[graphic omitted]-2}(η-C₅Me₅)(PPh₃)]ClO₄ and [[graphic omitted]-2}(η-C₅Me₅)(py)]ClO₄ but it is unidentate in the compound [Rh(C₆H₄NO₂-2)(η-C₅Me₅)(bipy)]ClO₄.