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

Abstract

Crystalline compounds of general composition (NBu 4 ) 2 [M II 2 (dhbq) 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 NBu 4 Br in aqueous solution at 115 °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 II 2 (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 in the presence of Zn(OAc) 2 and NBu 4 Br 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 NBu 4 Br affords crystalline samples of the chloranilate (NBu 4 ) 2 [Mn II 2 (can) 3 ], which contains two interpenetrating (10,3)- a [Mn II 2 (can) 3 ] 2– networks of opposite hand.