Syntheses, Characterization, and X-ray Crystal Structures of Mono-Lacunary Dawson Polyoxometalate-Based Organosilyl Complexes

• Published in: European Journal of Inorganic Chemistry 2006-12, Vol.2006 (23), p.4834-4842
• Main Authors: Kato, Chika Nozaki, Kasahara, Yuhki, Hayashi, Kunihiko, Yamaguchi, Asuka, Hasegawa, Takeshi, Nomiya, Kenji
• Format: Article
• Language: English
• Subjects: Polyoxometalates; Silicon; Tungsten; X-ray diffraction
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.200600479

The syntheses and crystal structures of a series of organosilyl polyoxotungstate derivatives with the Dawson monovacant phosphotungstate [α2‐P2W17O61]10– are described. The polyoxometalates (Me2NH2)5H[α2‐P2W17O61{O[Si(CH2)3SH]2}]·6H2O (Me2NH2‐1), (Me2NH2)6[α2‐P2W17O61{O[Si(CH2)3SCN]2}]·3H2O (Me2NH2‐2), and (Me2NH2)6[α2‐P2W17O61{O(SiPh)2}]·4H2O (Me2NH2‐3) were obtained as analytically pure, homogeneous yellow crystals by the reaction of mono‐lacunary Dawson polyoxotungstate with HS(CH2)3Si(OMe)3, NCS(CH2)3Si(OEt)3, and PhSiCl3, respectively, in an HCl/water/acetonitrile mixed solution or a water/acetonitrile mixed solution, followed by crystallization from water in the dark. Single‐crystal X‐ray structure analyses revealed that the four‐coordinate –Si–O–Si– bonding of the organosilyl groups {O[Si(CH2)3SH]2}, {O[Si(CH2)3SCN]2}, and {O(SiPh)2} is attained through four oxygen atoms in the mono‐lacunary site of the polyanion, resulting in an overall C1 symmetry for Me2NH2‐1 and Me2NH2‐2 and Cs symmetry for Me2NH2‐3. In the molecular structures of Me2NH2‐1 and Me2NH2‐2, a unique configuration of the organosilyl groups is observed in the solid state, i.e. the equatorial and axial bonding of each of the two HS(CH2)Si moieties in the {O[Si(CH2)3SH]2} group for Me2NH2‐1 and the two NCS(CH2)3Si moieties oriented in a syn fashion in the {O[Si(CH2)3SCN]2} group for Me2NH2‐2. The characterization of Me2NH2‐(1–3) was accomplished by elemental analysis, TG/DTA, and FT‐IR, solution (1H, 13C, and 31P) NMR, and solid‐state 13C NMR spectroscopy. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)