Oxomolybdenum coordination compounds with pyridine. Syntheses and structures of [Mo4O8(OCH3)(2)Cl2L4]center dot 2L (L = Py, 4-MePy), [Mo4O8(OCH3)(4)(4-MePy)(4)], [Mo6O12(OCH3)(6)Py-4] and [Mo10O26Py8]center dot 7Py

(PyH)(2)[MoOCl5] reacts with methanol and pyridine or 4-methylpyridine to g ive neutral oxomolybdenum(V) and oxomolybdenum(V,VI) clusters built of Mo2O 42+ units, i.e. tetranuclear [Mo4O8(OCH3)(2)Cl2Py4]. 2Py (Py = pyridine (C5 H5N)) (i), [Mo4O8(OCH3)(2)Cl-2(4-MePy)(4)]. 2(4-MePy) (4-MePy = 4-methylpyr idine (C6H7N)) (ii), [Mo4O8(OCH3)(4)(4-MePy)(4)] (iii), hexanuclear [Mo6O12 (OCH3)(6)Py-4] (iv) and decanuclear [Mo10O26Py8]. 7Py (v). It was shown by the X-ray structure analysis that i and iii contain the same [Mo4O4(mu(2)-O )(2)(mu(3)-O)(2)(mu(2)-OCH3)(2)](2+) core to which different peripheral lig ands are attached. The structure of ii is analogous to that of i, based on the similarity of infrared and far infrared spectra. Molecules of iv were s hown to contain a planar arrangement of six molybdenum atoms linked togethe r by oxo and methoxo bridging groups. The X-ray structure analysis of v rev ealed the presence of molybdenum(V) and molybdenum(VI) atoms. Neutral, deca nuclear molecules of v are built of four Mo2O42+ units which are connected with two molybdenum(VI) centres. (C) 2000 Elsevier Science S.A. All rights reserved.