Spontaneous dehydrocoupling in peri-substituted phosphine-borane adducts
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Bis(borane) adducts Acenap(PiPr2·BH3)(PRH·BH3) (Acenap = acenaphthene-5,6-diyl; 4a, R = Ph; 4b, R = ferrocenyl, Fc; 4c, R = H) were synthesised by the reaction of excess H3B·SMe2 with either phosphino-phosphonium salts [Acenap(PiPr2)(PR)]+Cl− (1a, R = Ph; 1b, R = Fc), or bis(phosphine) Acenap(PiPr2)(PH2) (3). Bis(borane) adducts 4a–c were found to undergo dihydrogen elimination at room temperature, this spontaneous catalyst-free phosphine-borane dehydrocoupling yields BH2 bridged species Acenap(PiPr2)(µ-BH2)(PR·BH3) (5a, R = Ph; 5b, R = Fc; 5c, R = H). Thermolysis of 5c results in loss of the terminal borane moiety to afford Acenap(PiPr2)(µ-BH2)(PH) (14). Single crystal X-ray structures of 3, 4b and 5a–c are reported.
Taylor , L J , Surgenor , B A , Wawrzyniak , P , Ray , M J , Cordes , D B , Slawin , A M Z & Kilian , P 2016 , ' Spontaneous dehydrocoupling in peri -substituted phosphine-borane adducts ' Dalton Transactions , vol 45 , no. 5 , pp. 1976-1986 . DOI: 10.1039/C5DT02539G
Copyright 2015 the Authors. This article is licensed under a Creative Commons Attribution 3.0 Unported Licence (http://creativecommons.org/licenses/by/3.0/).
This work was financially supported by the EPSRC and COST action CM1302 SIPs.