Acetato complexes of molybdenum(V): A novel tetranuclear core based on the metal–metal bonded {Mo 2O 4} 2+ units

Abstract

A series of acetato complexes of molybdenum(V), based on the singly metal–metal bonded {Mo 2O 4} 2+ structural fragment, has been prepared. A dinuclear (PyH) 3[Mo 2O 4Cl 4(OOCCH 3)] · CH 3CN ( 1) (PyH + = pyridinium cation, C 5H 5NH +) was obtained upon the reaction of (PyH) 5[MoOCl 4(H 2O)] 3Cl 2 with the equimolar solution of pyridine and acetic acid in acetonitrile at ambient conditions. The acetato ligand in 1 is coordinated to a pair of molybdenum atoms in a syn– syn bidentate bridging manner. (PyH) n [MoOBr 4] n afforded in an analogous synthetic procedure a tetranuclear cluster, [Mo 4O 8(OOCCH 3) 3(OH)Py 4] · 1/2CH 3CN · 1/2H 2O ( 3), with a novel core which may be envisioned as the acetate- and hydroxide-assisted assembly of {Mo 2O 4} 2+ building blocks. Its structure is presented in terms of known tetranuclear clusters which are also composed of two {Mo 2O 4} 2+ units. The acetato ligands in 3 adopted apart from bidentate bridging binding modes also a monodentate one. Partial substitution of chlorido ligands in (PyH) 3[Mo 2O 4Cl 4(OOCCH 3)] · CH 3CN ( 1) with pyridine resulted in a neutral [Mo 2O 4Cl(OOCCH 3)Py 3] · Pr i OH · Py ( 2) which retained the original acetate coordination. The title compounds were fully characterized by X-ray diffraction studies and infrared vibrational spectroscopy.