Oxomolybdenum coordination compounds with pyridine. Syntheses and structures of [Mo4O8(OCH3)2Cl2L4]·2L (L=Py, 4-MePy), [Mo4O8(OCH3)4(4-MePy)4], [Mo6O12(OCH3)6Py4] and [Mo10O26Py8]·7Py

(PyH)2[MoOCl5] reacts with methanol and pyridine or 4-methylpyridine to give neutral oxomolybdenum(V) and oxomolybdenum(V,VI) clusters built of Mo2O4 2+ units, i.e. tetranuclear [Mo4O8(OCH3)2Cl2Py4]·2Py (Py=pyridine (C5H5N)) (i), [Mo4O8(OCH3)2Cl2(4-MePy)4]·2(4-MePy) (4-MePy=4-methylpyridine (C6H7N)) (ii), [Mo4O8(OCH3)4(4-MePy)4] (iii), hexanuclear [Mo6O12(OCH3)6Py4] (iv) and decanuclear [Mo10O26Py8]·7Py (v). It was shown by the X-ray structure analysis that i and iii contain the same [Mo4O4(μ2-O)2(μ3-O)2(μ2-OCH3)2]2+ core to which different peripheral ligands 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 shown to contain a planar arrangement of six molybdenum atoms linked together by oxo and methoxo bridging groups. The X-ray structure analysis of v revealed the presence of molybdenum(V) and molybdenum(VI) atoms. Neutral, decanuclear molecules of v are built of four Mo2O4 2+ units which are connected with two molybdenum(VI) centres.