Neutral one-dimensional metal chains consisting of alternating anionic and cationic rhodium complexes

Abstract

The metallophilic interactions were investigated within chains of oppositely charged rhodium carbonyl complexes. The cationic [Rh(CO)₂(L)]⁺ (L = 2,2′-bipyridine and 1,10-phenanthroline) and anionic [RhCl₂(CO)₂]⁻ units were self-assembled into one dimensional rhodium chains supported by electrostatic interactions. The array of Rh centers in {[Rh(CO)₂(2,2′-bpy)][RhCl₂(CO)₂]}_n was found to be nearly linear with a Rh⋯Rh⋯Rh angle of 170.927(11)° and Rh⋯Rh distances of 3.3174(5) Å and 3.4116(5) Å. The crystal structure of {[Rh(CO)₂(1,10-phen)][RhCl₂(CO)₂]} consisted of two sets of crystallographically independent chains with slightly different Rh⋯Rh⋯Rh angles (170.275(9)° and 159.573(9)°). The higher linearity allowed closer packing of the rhodium complexes. The Rh⋯Rh distances were 3.2734(3) Å and 3.3155(3) Å for the more linear and 3.3498(3) Å and 3.3211(3) Å for the less linear system. The existence of metallophilic interactions was confirmed computationally by TD-DFT and QTAIM analysis. The computational results also indicated that the intermolecular charge transfer from the cation to the anion had a significant contribution to the absorption properties of the chain compounds.