Boron-boron bond oxidative addition to rhodium(I) and iridium(I) centres

William Clegg, Fiona J. Lawlor, Todd B. Marder, Paul Nguyen, Nicholas C. Norman, A. Guy Orpen, Michael J. Quayle, Craig R. Rice, Edward G. Robins, Andrew J. Scott, Fabio E.S. Souza, Graham Stringer, George R. Whittell

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50 Citations (Scopus)


The reaction between the diborane(4) compound B2(1,2-O2C6H4)2 and either of the rhodium(I) complexes [RhCl(PPh3)3] or [{Rh(μ-Cl)(PPh3)2}2] afforded the colourless rhodium(III) bis(boryl) species [RhCl(PPh3)2-{B(1,2-O2C6H 4)}2]. Similar reactions have been carried out with the diborane(4) compounds B2(1,2-O2-4-ButC6H3) 2, B2(1,2-O2-3,5-But 2C 6H2)2, B2(1,2-O2-3-MeC6H3)2, B2(1,2-O2-4-MeC6H3)2, B2(1,2-O2-3-MeOC6H3)2, B2(1,2-S2C6H4)2, B2(1,2-S2-4-MeC6H3)2 and B2[R,R-1,2-O2CH(CO2Me)CH(CO 2Me)]2 affording analogous rhodium complexes all of which have been characterised spectroscopically. The complexes derived from the reactions with B2(1,2-O2C6H4)2 and B2(1,2-O2-3-MeC6H3)2 have also been characterised by X-ray crystallography, the structures comprising a five-co-ordinate rhodium centre with a square-based-pyramidal geometry in which the apical site is occupied by a boryl group and the phosphines are mutually trims in basal positions. Reactivity studies have also been carried out for [RhCl(PPh3)2{B(1,2-O2C6H 4)}2]. Hydrolysis or alcoholysis with catechol afforded [RhH2Cl(PPh3)3] and either B2(1,2-O2C6H4)2(μ-O) or B2(1,2-O2C6H4)3 and addition of the phosphines PMe3, PEt3 and PMe2Ph afforded the new bis(boryl) compounds cis,mer-[RhCl(PMe3)3{B(1,2-O2C 6H4)}2], [RhCl(PEt3)2-{B(1,2-O2C6H 4)}2] and cis,mer-[RhCl(PMe2Ph)3{B(1,2-O2C 6H4)}2], the PEt3 complex having been characterised by X-ray crystallography and shown to be similar to the PPh3 complex. The iridium analogue [IrCl(PEt3)2-{B(1,2-O2C6H 4)}2] was also prepared from the reaction between [IrCl(PEt3)3] and B2(1,2-O2C6H4)2 and shown by X-ray crystallography to be isomorphous with the rhodium complex. Reactions between [RhCl(PPh3)2-{B(1,2-O2C6H 4)}2] and the phosphines PPri 3, P(C6H11)3, 1,2-bis(diphenylphosphino)ethane (dppe) and 1,2-bis(dicyclohexylphosphino)ethane (dcpe) are also described although these do not result in new rhodium boryl complexes. The reaction between [{RhCl(dppe)}2] and B2(1,2-O2C6H4)2 afforded a compound tentatively assigned as [Rh(dppe)2{B(1,2-O2C6H4)}] with analogous compounds being formed with the diborane(4) compounds B2(1,2-O2-3-MeC6H3)2 and B2(1,2-O2-4-MeC6H3)2. Finally, the reaction between [Rh(PMe3)4]Cl and the diborane(4) compound B2(1,2-O2C6H4)2 is described which affords cis,mer-[RhCl(PMe3)3{B(1,2-O2C 6H4)}2]. Analogous reactions with B2(1,2-O2-3,5-But 2C 6H2)2, B2(1,2-O2-3-MeC6H3)2 and B2[R,R-1,2-O2CH(CO2Me)CH-(CO 2MeJ]2 afforded similar products.

Original languageEnglish
Pages (from-to)301-309
Number of pages9
JournalJournal of the Chemical Society - Dalton Transactions
Issue number2
Publication statusPublished - 21 Jan 1998
Externally publishedYes


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