Regioselective B-Cyclometalation of a Bulky o-Carboranyl Phosphine and the Unexpected Formation of a Dirhodium(II) Complex

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• 作者：Natalie Fey ; Mairi F. Haddow ; Rakesh Mistry ; Nicholas C. Norman ; A. Guy Orpen ; Timothy J. Reynolds ; Paul G. Pringle
• 刊名：Organometallics
• 出版年：2012
• 出版时间：April 9, 2012
• 年：2012
• 卷：31
• 期：7
• 页码：2907-2913
• 全文大小：362K
• 年卷期：v.31,no.7(April 9, 2012)
• ISSN：1520-6041

文摘

The bulky carboranyl monophosphine closo-1,2-B₁₀H₁₀C(H)C(P^tBu₂) (L) has been prepared in a one-pot procedure from o-carborane. The reaction of [PdCl₂(NCPh)₂] with L rapidly gave the binuclear B-cyclopalladate [Pd₂(渭-Cl)₂(魏²-L鈥?₂] (L鈥?= L deprotonated at B3) as a mixture of two diastereoisomers, assigned structures 1a and 1a鈥? The Cl bridges of 1a/1a鈥?are cleaved by the addition of PEt₃ to give the mononuclear [PdCl(魏²-L鈥?(PEt₃)] (2) as a single isomer, with the P atoms mutually trans. The metalation occurs at boron positions 3 and 6 in the carborane cluster, and DFT calculations show that the 3,6-borometalate is lower in energy than the isomeric 4,5-borometalate and 2-carbometalate. Treatment of [Rh₂Cl₂(CO)₄] with L led to the slow precipitation of the dirhodium(II) species [Rh₂(渭-Cl)₂(CO)₂(魏²-L鈥?₂] (3). The crystal structures of ligand L and complexes 1a, 2, and 3 have been determined.