Synthesis and Characterization of Oxygen/Sulfur-Bridged Incomplete Cubane-Type Clusters, [M3S4(Tpe)3]+ and [M3OS3(Tpe)3]+ (M = Mo and W), and a Mixed-Metal Cubane-Type Cluster, [Mo3PdS4Cl(Tpe)3

Abstract

Abstract The reaction of [Mo3S4(H2O)9]4+ (1) and [Mo3OS3(H2O)9]4+ (2) with hydrotris(pyrazolyl)ethanol (HTpe) ligands produced [Mo3S4(Tpe)3]PF6·3CH2Cl2 ([5]PF6·3CH2Cl2) and [Mo3OS3(Tpe)3]PF6·4CH2Cl2 ([6]PF6·4CH2Cl2), respectively, using solvent extraction. Furthermore, the tungsten analogous compounds, [W3S4(Tpe)3]PF6·4CH2Cl2 ([7]PF6·4CH2Cl2) and [W3OS3(Tpe)3]PF6·2.5CH2Cl2 ([8]PF6·2.5CH2Cl2) have been prepared using a similar procedure to that used in the preparation of 5. The cyclic voltammograms of 5, 6, and 7 show one reversible one-electron oxidation process and one reversible one-electron reduction process (5, E1/2 = −0.96 and 1.10 V; 6, E1/2 = −0.96 and 1.00 V; 7, E1/2 = −1.54 and 0.77 V: all values are given vs. SHE). Complex 8 also shows one reversible (E1/2 = 0.61 V) and one irreversible one-electron oxidation processes (Epc = 1.12 V) and one irreversible one-electron reduction process (Epc = −1.54 V). The reaction of 5 with organometallic compound [Pd2(dba)3] in CH3CN afforded [Mo3PdS4Cl(Tpe)3]·4.5CH2Cl2 ([11]·4.5CH2Cl2). Complex 11 showed a high catalytic activity for the intramolecular cyclization of 4-pentynoic acid to give γ-methylene-γ-butyrolactone in the presence of Et3N. X-ray structure analyses of [5]PF6·3CH2Cl2, [6]PF6·4CH2Cl2, [7]PF6·4CH2Cl2, [8]PF6·2.5CH2Cl2, and [11]·4.5CH2Cl2 revealed that each molybdenum or tungsten atom is bonded to the Tpe ligand.