Coordination Polymers of 2,5-Dihydroxybenzoquinone and Chloranilic Acid with the (10,3)-a Topology

Crystalline compounds of general composition (NBu4)(2)[M-2(II)(dhliq)(3)] (where M = Mn, Fe, Co, Ni, Zn, and Cd and dhbq(2-) is the dianion of 2,5-dihydroxybenzoquinone) are obtained by reaction of the divalent metal acetate (or the sulfate in the case of Fe) with 2,5-diaminobenzoquinone and an excess of NBu4Br in aqueous solution at 115 degrees C in sealed tubes. The dhbq(2-) ligand is generated in situ by hydrolysis of the 2,5-diaminobenzoquinone. We have been unable to obtain these compounds in a crystalline form suitable for single crystal X-ray diffraction studies directly from H(2)dhbq itself A structural feature common to this series is the presence of two interpenetrating [M-2(II)(dhbq)(3)](2-) coordination networks, each with the chiral (10,3)-a topology, with the two independent nets being of opposite hand-unprecedented circumstances for dhbq-based coordination polymers. Crystals of the same zinc compound as that obtained above from 2,5-diaminobenzoquinone can alternatively be obtained by in situ aerial oxidation of 1,2,4,5-tetrahydroxybenzene presence of Zn(OAc)(2) and NBu4Br in aqueous methanol at room temperature. Analogous in situ aerial oxidation of 1,2,4,5-tetrahydroxy-3,6-dichlorobenzene in the presence of Mn(OAc)(2) and NBu4Br affords crystalline samples of the chloranilate (NBu4)(2)[Mn-2(II)(can)(3)], which contains two interpenetrating (10,3)-a [Mn-2(II)(can)(3)](2-) networks of opposite hand.