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

Abstract

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.