Cyanooxo molybdenum(IV) complexes with 2-pyrazinecarbonitrile and 2-pyrazinecarboxylate: Crystallographic and spectroscopic studies reveal metal-assisted nitrile hydrolysis

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• 作者：Dariusz Matoga ; Janusz Szklarzewicz ; Krzysztof Lewiń ; ski
• 关键词：Molybdenum ; Cyano ; Complexes ; Hydrolysis ; Nitrile ; Carboxylate
• 刊名：Polyhedron
• 出版年：2008
• 出版时间：21 August 2008
• 年：2008
• 卷：27
• 期：12
• 页码：2643-2649
• 全文大小：728 K

文摘

The pH-control of a reaction between tetracyanooxomolybdate(IV) and 2-pyrazinecarbonitrile (pcn), in aqueous-ethanolic solution under ambient conditions, affords the Mo(IV) mixed-ligand complex anions [Mo(CN)₄O(pcn)]²⁻ (1) or [Mo(CN)₄O(Hpca)]²⁻ (2) with a monodentately bound 2-pyrazinecarboxylic acid (Hpca), resulting from metal-assisted organonitrile hydrolysis. The acid undergoes slow rearrangement to a bidentate mode in [Mo(CN)₃O(pca)]²⁻ (3), which is confirmed by means of UV–Vis spectroscopy. The nitrile hydrolysis, favored by the basic conditions, has been ascertained by elemental analyses as well as IR, ¹H and ¹³C NMR spectroscopy. The use of Hpca instead of pcn in the synthetic procedure results in the direct formation of [Mo(CN)₃O(pca)]²⁻ (3) with the bidentate 2-pyrazinecarboxylate. The coordination versatility of 2-pyrazinecarboxylate toward cyanooxomolybdenum(IV) complexes is demonstrated by the IR and UV–Vis spectroscopy of solids with [Mo(CN)₄O(Hpca)]²⁻ and [Mo(CN)₃O(pca)]²⁻ ions, and the definitive evidence for the structure of [Mo(CN)₃O(pca)]²⁻ is provided by single-crystal X-ray crystallography. The chemical formulations of all the complexes, isolable as [PPh₄]⁺ salts, have been verified with microanalyses, spectroscopic measurements and X-ray crystal structures of 1 and 3.