Trapping tetramethoxyzincate and -cobaltate(II) between Mo24+ units

Two compounds of a new type, [MO2](CH3O)(2)M(CH3O)(2)[Mo-2] where [Mo-2] is an abbreviation for MO2[(p-MeOC6H4)-NCHN(p-MeOC6H4)](3) and M = Zn (1) and Co (2), are reported. Discrete [M(OR)(4)](2-) ions, either as such or in the mu(2),eta(4) role, have not heretofore been described. In these compounds they have distorted tetrahedral structures and bridge two [MO2] groups in much the same way as did SO42-, MoO42-, and WO42- ions in other recently reported compounds (Cotton, F. A.; Donahue, J. P.; Murillo, C. A. Inorg. Chem. 2001, 40, 2229). The H-1 NMR spectrum of 1 and the visible spectrum and magnetic properties of 2 are consistent with these structures. The M(OCH3)(4) bridges are moderately effective in coupling the two [Mo2] redox centers. Compounds 1 and 2 may also be viewed as having Zn-II and Co-II centers tetrahedrally coordinated by the bidentate ligand [Mo-2[(P-MeOC6H4)NCHN(p-MeOC6H4)](3)-(OMe)(2)](-). From that point of view they may be compared with Zn(DPM)(2) and Co(DPM)(2) (3), where DPM is the anion of dipivaloylmethane. For purposes of comparison, 3 has been fully characterized structurally, spectroscopically, and magnetically. Close analogies between 2 and 3 are shown to exist.