Mo(W)/Cu/S Cluster-Based Supramolecular Arrays Assembled from Preformed Clusters [Et4N]4[WS4Cu4I6] and [(n-Bu)4N]2[MoOS3Cu3X3] (X = I, SCN) with Flexible Ditopic Ligands

Abstract

In our working toward the rational design and synthesis of cluster-based supramolecular architectures, a set of new [WS4Cu4]- or [MoOS3Cu3]-based supramolecular assemblies have been prepared from reactions of preformed cluster compounds [Et4N]4[WS4Cu4I6] (1) and [(n-Bu)4N]2[MoOS3Cu3X3] (2, X = I; 3, X = SCN) with flexible ditopic ligands such as dipyridylsulfide (dps), dipyridyl disulfide (dpds), and their combinations with dicyanamide (dca) anion and 4,4'-bipy. The cluster precursor 1 reacted with dps or dpds and sodium dicyanamide (dca) in MeCN to produce [WS4Cu4I2(dps)3].2MeCN (4.2MeCN) and [WS4Cu4(dca)2(dpds)2].Et2O.2MeCN (5.Et2O.2MeCN), respectively. On the other hand, treatment of 2 with dpds in DMF/MeCN afforded [MoOS3Cu3I(dpds)2].0.5DMF.2(MeCN)0.5 (6.0.5DMF.2(MeCN)0.5) while reaction of 3 with sodium dicyanamide (dca) and 4,4'-bipy in DMF/MeCN gave rise to [MoOS3Cu3(dca)(4,4'-bipy)1.5].DMF.MeCN (7.DMF.MeCN). Compounds 4.2MeCN, 5.Et2O.2MeCN, 6.0.5DMF.2(MeCN)0.5, and 7.DMF.MeCN have been characterized by elemental analysis, IR spectroscopy, and single-crystal X-ray crystallography. Compound 4 contains a 2D layer array made of the saddle-shaped [WS4Cu4] cores interlinked by three pairs of Cu-dps-Cu bridges. Compound 5 has another 2D layer structure in which the [WS4Cu4] cores are held together by four pairs of Cu-dca-Cu and Cu-dpds-Cu bridges. Compound 6 displays a 1D spiral chain structure built of the nido-like [MoOS3Cu3] cores via two pairs of Cu-dpds-Cu bridges. Compound 7 consists of a 2D staircase network in which each [MoOS3Cu3(4,4'-bipy]2 dimeric unit interconnects with four other equivalent units by a pair of 4,4'-bipy ligands and two pairs of dca anions. The [WS4Cu4] core in 4 or 5 and the [MoS3Cu3] core in 7 show a planar 4-connecting node and a seesaw-shaped 4-connecting node, respectively, which are unprecedented in cluster-based supramolecular compounds. The successful assembly of 4-7 from the three cluster precursors 1-3 through flexible ditopic ligands provides new routes to the rational design and construction of complicated cluster-based supramolecular arrays.