Weak intermetallic bonding. A rare example of molecular stacking in a neutral square planar second-row transition-metal complex. X-Ray crystal structures of [Rh(cod)(Cl)(dmpH)] and [Rh(CO)2(Cl)(pzH)](cod = cyclo-octa-1,5-diene; dmpH = 3,5-dimethylpyrazole; pzH = pyrazole)

Abstract

The molecular geometry of [Rh(cod)(Cl)(dmpH)](cod = cyclo-octa-1,5-diene; dmpH = 3,5-dimethyl-pyrazole) is normal in all respects with the heterocycle almost perpendicular to the Rh co-ordination plane and intermolecular Rh ⋯ Rh 4.49 Å; by contrast the crystal structure of [Rh(CO)₂(Cl)(pzH)](pzH = pyrazole) provides a classic example of molecular ‘stacking’, with Rh–Rh long at 3.4522(4)Å along the one-dimensional chain.