Dinuclear cobalt(II) complexes with double phosphate ester bridges and tetradentate ligands having anisole or quinoline appendages.

Phosphate esters provide a rigid and stable polymeric backbone in nucleic acids. Metal complexes with phosphate ester groups have been synthesized as structural and spectroscopic models of phosphate-containing enzymes. Dinucleating ligands are used extensively to synthesize model complexes since they provide the support required to stabilize such complexes. The crystal structures of two dinuclear Co complexes, namely bis(μ-diphenyl phosphato-κO:O')bis({2-methoxy-N,N-bis[(pyridin-2-yl)methyl]aniline-κN,N',N'',O}cobalt(II)) bis(perchlorate), [Co(CHOP)(CHNO)](ClO), and bis(μ-diphenyl phosphato-κO:O')bis({N,N-bis[(pyridin-2-yl)methyl]quinolin-8-amine-κN,N',N'',O}cobalt(II)) bis(perchlorate), [Co(CHOP)(CHN)](ClO), with tetradentate 2-methoxy-N,N-bis[(pyridin-2-yl)methyl]aniline (L) and N,N-bis[(pyridin-2-yl)methyl]quinolin-8-amine (L) ligands are reported. The complexes have similar structures, with distorted octahedral geometries around the metal centres. Both are centrosymmetric (Z' = 0.5), with the Co centres doubly bridged by diphenyl phosphate ester groups. A number of aromatic-aromatic interactions are present and differ between the two complexes as the anisole group in L is replaced by a quinoline group in L. A detailed study of these interactions is presented.