η3-Allyl rhodium complexes with azolate ligands. Crystal structures of the trinuclear 1,2,4-triazolate (tz) complexes [Rh3(µ-tz)3(η3-C3H5)6] and [Rh3(µ3-tz)(µ-Cl)Cl(η3-C3H5)2(CO)4]·0.5C2H4Cl2

Abstract

The η3-allyl rhodium compound [Rh(acac)(η3-C3H5)2](acac = acetylacetonate) reacts with azole ligands to give the new azolate complexes [Rh3(µ-az)3(η3-C3H5)6][az = tetrazolate (ttz)(1), 1,2,4-triazolate (tz)(2), benzotriazolate (btz)(3), or imidazolate (im)(4)]. A single-crystal X-ray diffraction study on complex (2) has established that its structure consists of discrete trinuclear complexes in which each rhodium atom is bridged by the 1,2,4-triazolate ligands through the non-adjacent nitrogen atoms to form a multiatomic ring. Complexes (2) and (1) react with [Rh2(µ-Cl)2(CO)4] to give the mixed-valence trinuclear complexes [Rh3(µ3-az)(µ-Cl)Cl(η3-C3H5)2(CO)4][az = tz (10) or ttz (11)]. The crystal structure of complex (10) has confirmed the existence of trinuclear molecules in which a chlorine atom and a triazolate bridge Rh(CO)2 and Rh(η3-C3H5)2 moieties; in addition the remaining nitrogen atom of the triazolate ligand completes the square-planar co-ordination of a RhCl(CO)2 unit. In the crystal, there is an intermolecular Rh–Rh distance of 3.393(1)A. Complex (2) reacts with [Rh2(µ-Cl)2(η3-C3H5)4] to give the trinuclear complex [Rh3(µ3-tz)(µ-Cl)Cl(η3-C3H5)6]. Heterobridged binuclear pyrazolate (pz) complexes of formula [Rh2(µ-pz)(µ-X)(η3-C3H5)4](X = Cl, OH, or N3) have also been prepared.