Synthese, Reaktivität und Komplexeigenschaften von nido ‐2,3,5‐Tricarbahexaboranen

Syntheses, Reactivity and Complexation Properties of nido ‐2,3,5‐Tricarbahexaboranes By double hydroboration of 1,3‐dihydro‐1,3‐diborafulvenes 2 or 4,5‐diisopropylidene‐1,3‐diborolanes 3 with (Et 2 BH) 2 and subsequent loss of triethylborane derivatives 1 of 2,3,5‐tricarbahexaborane are formed under mild conditions. The stability of the nido ‐carboranes 1 depends on the substituents in the basal positions. After deprotonation, the tricarbahexaboranate ion ( 1 — H) — functions as a cyclopentadienyl analogue (C 5 H 5 ) — , and its reaction with allylnickel bromide dimer gives the allylnickel complexes 8a, b . Reaction of octacarbonyl dicobalt with 1b yields the dicarbonylcobalt complex 10b . Treatment of 1e with [(C 5 H 5 )Ni(CO)] 2 results in the formation of the di‐nuclear carbonyl‐bridged complex 12e .