The Interplay of Alkylidyne and Carbaborane Ligands at Metal Centers II: Proton-Mediated Reactions1

Silver Phosphanes Partnered with Carborane Monoanions: Synthesis, Structures and Use as Highly Active Lewis Acid Catalysts in a Hetero-Diels–Alder Reaction

“…Resonances due to {BH} groups are observed at d 2.25 and d 1.85 in the ratio 1:10 (the latter is a 55 coincidence), with no high-field resonances potentially indicative of M À HÀB interactions observed. [48] That only two {BH} resonances are observed suggests that the {AgPPh 3 } fragment is fluxional over the surface of the cage and affords time-averaged C 5V symmetry in solution. This facile process is evidenced by no significant change observed in the spectrum when recorded at À 90 8C.…”

Metal complexes of monocarbon carboranes bearing C-amine or -amino substituents

“…The pathway for these reactions presumably involves formation of coordinatively and electronically saturated intermediate complexes Bu t -2-X-2-PPh 3 -2-{C(H)CO 2 Et}-closo-2,1-RhCB 10 -H 10 ] followed by insertion of the alkylidene ligand into an adjacent BH bond of the {closo-2,1-RhCB 10 } framework. There is ample precedent for such a step both from earlier work [22] and from studies with aminocarborane-rhenium complexes described below.…”

Alkylidyne-Metal Templated Triboronate Condensation

“…À (R alkyl, aryl; Cb C 2 B 9 H 9 Me 2 , C 2 B 10 H 10 Me 2 ), which have been systematically investigated by Stone and co-workers, [5] and it may be argued that for this class of complex, once again much of the negative charge is located within the carbaborane cage. The reactivity of 1 was investigated with respect to both ligand exchange and bridge-assisted metal ± metal bond-forming processes.…”

“…[2] We recently reported on cagelike silicon ± nitrogen compounds with covalently bonded heteroatoms. [3,4] Cyclopolyalkylsilazanes and alkylsilsesquiazanes have been known for a long time, [5] however these compounds have not been structurally characterized. Single crystals of (MeSi) 6 (NH) 9 (1) [6] have now been investigated by X-ray structure analysis for the first time.…”