Dimolybdenum(III) Complexes of −OSi(OtBu)3, −O2P(OtBu)2, and −OB[OSi(OtBu)3]2 as Single-Source Molecular Precursors to Molybdenum-Containing, Multi-Component Oxide Materials

The following dimolybdenum complexes containing −OSi(OtBu)3, −O2P(OtBu)2, and −OB[OSi(OtBu)3]2 ligands have been synthesized and structurally characterized:  Mo2(NMe2)4[OSi(OtBu)3]2 (1), Mo2(OtBu)4[OSi(OtBu)3]2 (2), Mo2(NMe)4{OB[OSi(OtBu)3]2}2 (3), Mo2(NMe2)2[μ-O2P(OtBu)2]2[O2P(OtBu)2]2 (4), Mo2(NMe2)2[OSi(OtBu)3]2[μ-O2P(OtBu)2]2 (5), and Mo2(NMe2)2[μ-O2P(OtBu)2]2{OB[OSi(OtBu)3]2}2 (6). The isolation and structural characterization of trans-
and cis-isomers of complexes 4 and 5 (4a and 4b, 5a and 5b, respectively) are also reported.
Studies of the thermal decompositions of the complexes (by thermogravimetric analysis and
solution 1H NMR spectroscopy) were performed. Xerogels with approximate compositions of
2MoO1.5·2P2O5 and 2MoO1.5·2P2O5·2SiO2 were derived from 4a and 5a or 5b, respectively,
via solution thermolyses (toluene). The as-synthesized (and dried) xerogels contain one equiv
of HNMe2 per molybdenum center (by combustion analysis, IR spectroscopy, and thermogravimetric analysis), and these materials have high surface areas (up to 270 m2 g-1). Upon
calcination at 300 °C, the coordinated amines are lost and the surface areas are significantly
reduced (to 40 m2 g-1 and

本研究成功合成并结构表征了一系列含有-OSi(OtBu)3、-O2P(OtBu)2及-OB[OSi(OtBu)3]2配体的二钼配合物，包括Mo2(NMe2)4[OSi(OtBu)3]2 (1)、Mo2(OtBu)4[OSi(OtBu)3]2 (2)、Mo2(NMe)4{OB[OSi(OtBu)3]2}2 (3)、Mo2(NMe2)2[μ-O2P(OtBu)2]2[O2P(OtBu)2]2 (4)、Mo2(NMe2)2[OSi(OtBu)3]2[μ-O2P(OtBu)2]2 (5)及Mo2(NMe2)2[μ-O2P(OtBu)2]2{OB[OSi(OtBu)3]2}2 (6)。此外，还报道了这些配合物中顺式和反式异构体（4a和4b、5a和5b）的分离和结构表征。通过热重分析和溶液1H NMR光谱对配合物的热分解进行了研究。通过溶液热解（甲苯）从4a和5a或5b中分别获得了组成约为2MoO1.5·2P2O5和2MoO1.5·2P2O5·2SiO2的干燥凝胶。合成的（并干燥的）凝胶中，每个钼中心含有一等分的HNMe2（通过燃烧分析、红外光谱和热重分析确定），这些材料具有极高的比表面积（高达270 m2 g-1）。在300°C的煅烧过程中，配位的胺基丢失，比表面积显著降低（降至40 m2 g-1）。