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In search of the PhB(mu-(NBu)-Bu-t)(2) (2)As-center dot radical: Experimental and computational investigations of the redox chemistry of group 15 bis-boraamidinates

Citation:

Konu J, Tuononen HM, Chivers T, Corrente AM, Boeré RT, Roemmele TL. In search of the PhB(mu-(NBu)-Bu-t)(2) (2)As-center dot radical: Experimental and computational investigations of the redox chemistry of group 15 bis-boraamidinates. Inorganic Chemistry [Internet]. 2008;47:3823-3831.

Abstract:

DFT calculations for the group 15 radicals [PhB(mu-(NBu)-Bu-t)(2)](2)M-center dot (M = P, As, Sb, Bi) predict a pnictogen-centered SOMO with smaller contributions to the unpaired spin density arising from the nitrogen and boron atoms. The reactions of Li-2[PhB(mu-NR)(2)] (R = Bu-t, Dipp) with PCl3 afforded the unsolvated complex LiP[PhB(mu-(NBu)-Bu-t)(2)](2) (1a) in low yield and CIP[PhB(mu-NDiPP)(2)] (2), both of which were structurally characterized. Efforts to produce the arsenic-centered neutral radical, [PhB(mu-(NBu)-Bu-t)(2)](2)As-center dot, via oxidation of LiAs[PhB(mu-(NBu)-Bu-t)(2)](2) with one-half equivalent of SO2Cl2, yielded the Zwitterionic compound [PhB(mu-(NBu)-Bu-t)(2)As(mu-(NBu)-Bu-t)(2)B(Cl)Ph] (3) containing one four-coordinate boron center with a B-Cl bond. The reaction of 3 with GaCl3 produced the ion-separated salt, [PhB(mu-(NBu)-Bu-t)(2)](2)As+GaCl4- (4), which was characterized by X-ray crystallography. The reduction of 3 with sodium naphthalenide occurred by a two-electron process to give the corresponding anion [{PhB(mu-(NBu)-Bu-t)(2)}(2)As](-) as the sodium salt. Voltammetric investigations of 4 and LiAs[PhB(mu-(NBu)-Bu-t)(2)](2) (1b) revealed irreversible processes. Attempts to generate the neutral radical [PhB(mu-(NBu)-Bu-t)(2)](2)As-center dot from these ionic complexes via in situ electrolysis did not produce an EPR-active species.

Notes:

Times Cited: 4Konu, Jari Tuononen, Heikki M. Chivers, Tristram Corrente, Andrea M. Boere, Rene T. Roemmele, Tracey L.

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