Synthesis, crystal structure and valence tautomerism of a 4,4′-bipyridine-bridged one-dimensional chiral cobalt complex

Abstract

A linear-chain cobalt coordination polymer, [Co(2,3-LH2)2(4,4′-bipy)]⋅2H2O⋅4,4′-bipy]n (1) (2,3-LH2=2,3-tetrahydroxy-9,10-dimethyl-9,10-dihydro- 9,10-ethanoanthracene, 4,4′-bipy=4,4′-bipyridine), has been synthesized and structurally characterized. Single-crystal X-ray analysis reveals that complex 1 is a chiral polymer assemblied from achiral components. The complex 1 crystallizes in the chiral space group P3221 and the central Co ion has a slightly distorted octahedral coordination environment. The temperature dependence of magnetic susceptibility indicates that the complex 1 undergoes valence tautomeric interconversion between low-spin ls-[CoIII(2,3-LH2Cat)(2,3-LH2SQ)] and high-spin hs-[CoII(2,3-LH2SQ)2] (2,3-LH2Cat=2,3-LH2catecholate, 2,3-LH2SQ=2,3-LH2semiquinone).