Influence of the Ligand Alkyl Chain Length on the Solubility, Aqueous Speciation, and Kinetics of Substitution Reactions of Water-Soluble M3S4 (M = Mo, W) Clusters Bearing Hydrox

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• 作者：Tom谩s F. Beltr谩n ; Rosa Llusar ; Maxim Sokolov ; Manuel G. Basallote ; M. Jes煤s Fern谩ndez-Trujillo ; Jose 脕ngel Pino-Chamorro
• 刊名：Inorganic Chemistry
• 出版年：2013
• 出版时间：August 5, 2013
• 年：2013
• 卷：52
• 期：15
• 页码：8713-8722
• 全文大小：425K
• 年卷期：v.52,no.15(August 5, 2013)
• ISSN：1520-510X

文摘

Water-soluble [M₃S₄X₃(dhbupe)₃]⁺ diphosphino complexes (dhbupe = 1,2-bis(bis(hydroxybutyl)phosphino)ethane), 1⁺ (M = Mo, X = Cl) and 2⁺ (M = W; X = Br), have been synthesized by extending the procedure used for the preparation of their hydroxypropyl analogues by reaction of the M₃S₄(PPh₃)₃X₄(solvent)_x molecular clusters with the corresponding 1,2-bis(bishydroxyalkyl)diphosphine. The solid state structure of the [M₃S₄X₃(dhbupe)₃]⁺ cation possesses a C₃ symmetry with a cuboidal M₃S₄ unit, and the outer positions are occupied by one halogen and two phosphorus atoms of the diphosphine ligand. At a basic pH, the halide ligands are substituted by hydroxo groups to afford the corresponding [Mo₃S₄(OH)₃(dhbupe)₃]⁺ (1_OH⁺) and [W₃S₄(OH)₃(dhbupe)₃]⁺ (2_OH⁺) complexes. This behavior is similar to that found in 1,2-bis(bis(hydroxymethyl)phosphino)ethane (dhmpe) complexes and differs from that observed for 1,2-bis(bis(hydroxypropyl)phosphino)ethane (dhprpe) derivatives. In the latter case, an alkylhydroxo group of the functionalized diphosphine replaces the chlorine ligands to afford Mo₃S₄ complexes in which the deprotonated dhprpe acts in a tridentate fashion. Detailed studies based on stopped-flow, ³¹P{¹H} NMR, and electrospray ionization mass spectrometry techniques have been carried out in order to understand the solution behavior and kinetics of interconversion between the different species formed in solution: 1 and 1_OH⁺ or 2 and 2_OH⁺. On the basis of the kinetic results, a mechanism with two parallel reaction pathways involving water and OH^{鈥?/sup> attacks is proposed for the formal substitution of halides by hydroxo ligands. On the other hand, reaction of the hydroxo clusters with HX acids occurs with protonation of the OH鈥?/sup> ligands followed by substitution of coordinated water by X鈥?/sup>.}