A DFT Study on the Stabilization of the B≡B Triple Bond in a Metallaborocycle: Contrasting Electronic Structures of Boron and Carbon Analogues.
Chemistry
; 23(41): 9746-9751, 2017 Jul 21.
Article
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| MEDLINE
| ID: mdl-28557024
The electronic structure of (η5 -Cp)2 Zr(NH2 -BB-NH2 ) (3 b) suggests that it could be a candidate for having a boron-boron triple bond in the cyclic system; however, computational studies shows that 3 b is a very high energy isomer on its potential energy surface. Replacement of amines with tricoordinate nucleophilic boron groups (η5 -Cp)2 Zr[B(PH3 )2 -BB-B(PH3 )2 ] (3 c) reduces the relative energy dramatically. The B≡B triple bond arises through the donation of two electrons from the metal fragment, ZrCp2 , to the in-plane π-bonding orbital of the central B-B unit. Strong σ-donating and chelating bis-phosphine ligands (Me2 P(CH2 )n PMe2 ), which stabilize donor-acceptor bonding interaction in gem-diborene L2 B-BBr2 (10), would be a good choice along the synthetic path towards 3 d, (η5 -Cp)2 Zr[B4 (Me2 P(CH2 )3 PMe2 )2 ]. A comparison of the energetics of the reaction leading to a cyclic boryne system (3 d), with the linear boryne isomer [(B2 NHCPh )2 ] shows that the angle strain from cyclization is compensated by stabilization from the metal.
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01-internacional
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MEDLINE
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En
Revista:
Chemistry
Asunto de la revista:
QUIMICA
Año:
2017
Tipo del documento:
Article
País de afiliación:
India
Pais de publicación:
Alemania