Isolation of an Annulated 1,4‐Distibabenzene Diradicaloid
Henric Steffenfauseweh, Dennis Rottschäfer, Yury V. Vishnevskiy, Beate Neumann, Hans‐Georg Stammler, Dariusz W. Szczepanik, Rajendra S. Ghadwal
Abstract
Abstract The first 1,4‐distibabenzene‐1,4‐diide compound [(ADC)Sb] 2 ( 5 ) based on an anionic dicarbene (ADC) (ADC=PhC{N(Dipp)C} 2 , Dipp=2,6‐ i Pr 2 C 6 H 3 ) is reported as a bordeaux‐red solid. Compound 5 , featuring a central six‐membered C 4 Sb 2 ring with formally Sb I atoms may be regarded as a base‐stabilized cyclic bis‐stibinidene in which each of the Sb atoms bears two lone‐pairs of electrons. 5 undergoes 2 e‐oxidation with Ph 3 C[B(C 6 F 5 ) 4 ] to afford [(ADC)Sb] 2 [B(C 6 F 5 ) 4 ] 2 ( 6 ) as a brick‐red solid. Each of the Sb atoms of 6 has an unpaired electron and a lone‐pair. The broken‐symmetry open‐shell singlet diradical solution for ( 6 ) 2+ is calculated to be 2.13 kcal mol −1 more stable than the closed‐shell singlet. The diradical character of ( 6 ) 2+ according to SS‐CASSCF (state‐specific complete active space self‐consistent field) and UHF (unrestricted Hartree‐Fock) methods amounts to 36 % and 39 %, respectively. Treatments of 6 with (PhE) 2 yield [(ADC)Sb(EPh)] 2 [B(C 6 F 5 ) 4 ] 2 ( 7 ‐E) (E=S or Se). Reaction of 5 with (cod)Mo(CO) 4 affords [(ADC)Sb] 2 Mo(CO) 4 ( 8 ).