A comparative study of the reactivity of the lightly stabilized cluster [Os₃(CO)₈{渭₃-Ph₂PCH₂P(Ph)C₆H₄}(渭-H)] towards tri(2-thienyl)-, tri(2-furyl)- and triphenyl-phosphine

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• 作者：Arun K. Raha ; Md. Nazim Uddin ; Shishir Ghosh ; Abdur R. Miah ; Michael G. Richmond ; Derek A. Tocher ; Ebbe Nordl ; er ; Graeme Hogarth ; Shariff E. Kabir
• 关键词：Triosmium ; Phosphines ; Addition reactions ; Isomerization ; Carbon-phosphorus bond cleavage ; DFT studies
• 刊名：Journal of Organometallic Chemistry
• 出版年：1 February, 2014
• 年：2014
• 卷：751
• 期：Complete
• 页码：399-411
• 全文大小：1291 K

文摘

Reactions of the lightly stabilized triosmium cluster [Os₃(CO)₈{渭₃-Ph₂PCH₂P(Ph)C₆H₄}(渭-H)] with tri(2-thienyl)phosphine (PTh₃) and tri(2-furyl)phosphine (PFu₃) are described and compared to analogous reactions with PPh₃. At room temperature, a number of products are isolated: [Os₃(CO)₁₀(渭-dppm)] from CO addition, [Os₃(CO)₈(PR₃){渭₃-Ph₂PCH₂P(Ph)C₆H₄}(渭-H)] from phosphine addition, [Os₃(CO)₉(PR₃)(渭-dppm)] from phosphine and CO addition and [Os₃(CO)₈(PR₃)₂(渭-dppm)] from addition of two equivalents of phosphine. The latter are shown by NMR and X-ray diffraction to exist as 1,2-isomers, whereby one phosphine is bound to the non-dppm-substituted center and the second shares an osmium atom with one end of the diphosphine. Heating 1,2-[Os₃(CO)₈(PTh₃)₂(渭-dppm)] at 100聽掳C results in its clean isomerization to the 1,1-isomer in which both monodentate phosphines are located on the same osmium atom. Prolonged heating of [Os₃(CO)₈(PR₃)₂(渭-dppm)] (R聽=聽Th, Ph) at 110聽掳C gives [Os₃(CO)₉(PR₃)(渭-dppm)] and the new lightly stabilized clusters [Os₃(CO)₇(PR₃){渭₃-Ph₂PCH₂P(Ph)C₆H₄}(渭-H)], the latter being formed by loss of phosphine and CO with concurrent metalation of a phenyl ring. Heating [Os₃(CO)₈(PFu₃)₂(渭-dppm)] at 110聽掳C gives [Os₃(CO)₉(PFu₃)(渭-dppm)] together with the carbon-phosphorus bond cleavage products [Os₃(CO)₇(渭-PFu₂)(渭₃-畏²-C₄H₂O)(渭-H)(渭-dppm)] and [Os₃(CO)₇(渭-PFu₂)(渭₃-畏²-C₆H₃CH₃)(渭-H)(渭-dppm)]. All new compounds were characterized by analytical and spectroscopic techniques together with single crystal X-ray diffraction analysis of nine clusters. Density functional theory (DFT) calculations have been carried out on isomers of [Os₃(CO)₈(PR₃)₂(渭-dppm)] in order to understand the observed isomer ratios.