Reactions of the octahydrotriborate(1–) anion, [B3H8]–, with some complexes of cobalt(I), cobalt(II), rhodium(I), and iridium(I), and the characterization of the ‘borallyl’ complex [IrIII(η3-B3H7)(CO)H(PPh3)2]

Abstract

The octahydrotriborate(1–) anion, [B₃H₈]^–, reacts with amine and tertiary phosphine complexes of cobalt(I) and cobalt(II) halides to give arachno-triborane-ligand adducts, B₃H₇L, together with B₂H₄L₂ and BH₃L (where L = pyridine or tertiary phosphine). A similar reaction occurs with trans-[Rh^I(CO)Cl(PPh₃)₂] and with [Ir^I(CO)Cl(PPh₃)₂]. The latter complex also yields the novel ‘borallyl’ compound [Ir^III(η³-B₃H₇)(CO)H(PPh₃)₂] which may also be described as a nido-iridatetraborane, [(IrB₃H₇)(CO)H(PPh₃)₂]. The spectroscopic properties and structure of this compound are discussed. The [B₃H₈]^– ion does not react with [Ir^I(CO)(dppe)₂]⁺ but [Ir^I(dppe)₂]⁺ is converted into [Ir^IIIH₂(dppe)₂]⁺(dppe = Ph₂PCH₂CH₂PPh₂).