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

In our working toward the rational design and synthesis of cluster-based suppramolecular 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.