Synthesis and Crystal Structures of Multidimensional Coordination Polymers Based on W/Cu/S Clusters with Flexible Imidazole Ligands

Abstract

Reactions of [WES3]2- (E = S, O) with CuX (X = NCS, CN, I) in the presence of bix (bix = 1,4-bis(imidazole-1-ylmethyl)benzene) in DMF or CH3CN resulted in the formation of two novel 2D --> 3D interpenetrating coordination polymers [S2W2S6Cu4(bix)2]n (1) and {[WS4Cu4(NCS)2(bix)3].CH3CN}n (2), a noninterpenetrating 3D polymer {[WS4Cu2(bix)].DMF}n (3), and two 2D sheet polymers [WS4Cu3(CN)(bix)]n (4) and {[OWS3Cu3(bix)2][I].DMF.2H2O}n (5), depending on the reaction temperature and the reagents used. Compound 1 contains a hexagonal prism of W2Cu4S6 cluster core, which serves as a 4-connecting node to link equivalent nodes via bix ligands, forming a 2D (4,4) net. In 2, a WCu4S4 core, which also acts as a 4-connecting node, connects the neighboring nodes either through single or double bix bridges, affording a different 2D (4,4) sheet. Inclined interpenetration occurs between two stacks of 2D sheets in the total structure of 1, while 2 involves a parallel interpenetration between the adjacent layers, both creating a 3D network. Compounds 1 and 2 represent the first examples of interpenetrating (4,4) frameworks with clusters as nodes and bidentate pyridyl-based ligands as linkers. Unlike 1 and 2, compound 3 has a noninterpenetrating 3D network, which is composed of the inorganic 1D (WS4Cu2)n chains linked by cis and trans bix ligands. Compound 4 features an inorganic 1D (WS4Cu3)n chain structure, which is linked by CN groups and bix ligands to form an infinite 2D network. Compound 5 is a 2D layer polymer with large inner cavities.