The syntheses of novel N-heterocyclic carbene (NHC) adducts of
group 13, 14 and 15 element hydrides are reported. Salt metathesis reactions between NaPH2 and IDipp ·GeH2BH2OTf (1)
(IDipp=1,3-bis(2,6-iisopropylphenyl)imidazol-2-ylidene) led to mixtures of the two isomers IDipp ·GeH2BH2PH2 (2a) and IDipp ·BH2GeH2PH2 (2b); by altering the reaction conditions an almost exclusive formation of 2b was achieved. Attempts to purify mixtures of 2a and 2b by re-crystallization from THF afforded a salt [IDipp ·GeH2BH2 · IDipp][PHGeH2BH2PH2BH2GeH2]
(4) that contains the novel anionic cyclohexyl-like inorganic heterocycle [PHGeH2BH2PH2BH2GeH2]􀀀 . In addition, the borane adducts IDipp ·GeH2BH2PH2BH3 (3a) and IDipp ·BH2GeH2PH2BH3
(3b) as even longer chain compounds were obtained from reactions of 2a/2b with H3B·SMe2 and were studied by NMR
spectroscopy. Accompanying DFT computations give insight into the mechanism and energetics associated with 2a/2b isomerization as well as their decomposition pathways.