Solvothermal assembly of a mixed-valence Cu(I,II) cyanide coordination polymer [Cu(II)Cu(I)2(µ-Br)2(µ-CN)2(bdmpp)]n by C–C bond cleavage of acetonitrile

Dissolving CuBr and 2,6-bis(3,5-dimethyl-1H-pyrazol-1-yl)pyridine (bdmpp) in MeCN followed by a solvothermal treatment afforded an unique mixed-valence Cu(I,II) cyanide coordination polymer [Cu(II)Cu(I)2(µ-Br)2(µ-CN)2(bdmpp)]n (1). Comparative reactions using CuCN and bdmpp under the same conditions gave rise to a different mixed-valence Cu(I,II) cyanide polymer [Cu(II)Cu(I)3(µ-CN)5(bdmpp)]n (2). Both reactions are involved in partial oxidation of Cu(I) into Cu(II) via O2 in open air while in the case of 1, the cyanide may be generated in situ from the C–C cleavage of acetonitrile under solvothermal conditions. 1 consists of a 2D (6,3) layer network in which the [Cu(I)8{Cu(II)(bdmpp)}4(µ-Br)8(µ-CN)7]n double chains are interconnected by a pair of µ-CN bridges. 2 shows a 2D (6,3) folded network in which the [Cu(I)6{Cu(II)(µ-CN)(bdmpp)}2(µ-CN)7]n double chains are inter-linked by a pair of µ-CN bridges. The luminescent properties of 1 and 2 in solid state at ambient temperature were also investigated.