Complexes of a hexa-nitrile dianion with neutral, chelating co-ligands: Self-assembly, structure and magnetism

Abstract

Several new first-row transition-metal complexes have been synthesised by combining the polynitrile dianion HCTMCP²⁻ (hexacyanotrimethylenecyclopropandiide) with neutral, chelating co-ligands; 2,2′-bipyridine, 1,10-phenanthroline and 3-(2-pyridyl)pyrazole. The products cover a remarkable range of species including mononuclear complexes, dimers, charge-separated species and coordination polymers. Complexes containing 2,2′-bipyridine take the form [Mn(2,2′-bipy)₂(HCTMCP)]₂·2MeOH (1) or [M(2,2′-bipy)₃](HCTMCP) (2Fe and 2Co) which are dimeric and charge-separated products, respectively. The products obtained using 1,10-phenanthroline were the discrete complex [Co(HCTMCP)(1,10-phen)₂(H₂O)]·H₂O·MeCN (3) and the 1D coordination polymer [Mn(HCTMCP)(1,10-phen)(H₂O)(MeOH)] (4). Complexes using the 3-(2-pyridyl)pyrazole co-ligand (pypzH) form similar 1D complexes to 4, namely [Mn(pypzH)(HCTMCP)(MeOH)(H₂O)] (5) and [M(pypzH)(HCTMCP)(MeOH)₂] (6Co and 6Fe), albeit with different hydrogen-bonding motifs between the chains. The polymeric HCTMCP complexes show weak to zero antiferromagnetic coupling between metal centres and thus no long-range ordering.