Borohydride boron-hydrogen activation and dimerization by a doubly bonded, early-transition-metal organodimetallic complex. Ditantalladiborane syntheses as models for dehydrodimerization of methane to ethane

Abstract

The 2-D INEPT-INADEQUATE spectrum for 7 (Figure 2) is also irrefutable evidence for structural identification.7 Note that 8 (Figure 3b) would show a connected to b and b connected to c. The spectrum clearly shows a directly bonded to both b and c, with two-bond coupling between b and c and three-bond coupling between c and d.10•11

Metallaboranes of the Early Transition Metals: Direct Synthesis and Characterization of [{(η5‐C5Me5)Ta}2BnHm] (n=4, m=10; n=5, m=11), [{(η5‐C5Me5)Ta}2B5H10(C6H4CH3)], and [{(η5‐C5Me5)TaCl}2B5H11]

“…Despite the availability of well-developed routes to metallaboranes of Group 6-9 metals, to our knowledge examples of characterized Group 5 metallaboranes are very rare. [21] Tantalaboranes [(Cp*Ta) 2 A C H T U N G T R E N N U N G (B 2 H 6 ) 2 ] [22] and [(Cp*Ta)Cl 2 B 4 H 8 ] [23] were synthe- (4) in modest yield. Compounds 1-3 are air-and moisture-sensitive but 4 is reasonably stable in air.…”

Structure and decomposition of [HFe(CO)4(B2H5)], a revised behavior of an old uncharacterized complex

“…Nevertheless the BeB distance (1.907 A) which is longer than the usual bridged B 2 (m-H)M (M ¼ Ru) one (1.733e1.840) [13,16,20,53,54] in the complexed state, does not support this view. In the bimetallic species (C 5 Me) 2 Ta 2 (mBr) 2 (B 2 H 6 ) [55], the BeB bond exhibits a close distance to ours (1.88 A). It has been concluded that this parameter is not consistent with a strong BeB bond.…”

Molecular Models of Solid State Metal Boride Structures

“…Although the reaction of metal chlorides with borohydride is a known method for the production of hydrides (and reduction of the metal center), what has not been appreciated is the fact that conversion of a polychloride to a polyborohydride permits H elimination with the formation of BB and MB bonds to be competitive with loss of borane to form a polyhydride. It was the work of Ting and Messerle (23), that demonstrated this unambiguously for the "rst time. In contrast, something unanticipated before our work is the fact that BH THF readily reacts with the same substrates to form metallaboranes with the chlorine being eliminated as BH Cl in all cases except one.…”