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Syntheses and structures of new alkali-metal boraamidinates and ferrocenyl aminoboranes†‡§
Andrea M. Corrente,Tristram Chivers
New Journal of Chemistry Pub Date : 06/28/2010 00:00:00 , DOI:10.1039/C0NJ00279H
Abstract

The ferrocenyl bis(amino)boranes FcB[N(H)R]2 (Fc = ferrocenyl; 1a, R = tBu, 1b, R = Dipp) and 1,1′-Fc{B[N(H)tBu]2}2 (2) are obtained by the reactions of [Li][N(H)R] with the corresponding ferrocenyl dibromoboranes FcBBr2 and 1,1′-Fc(BBr2)2. In a similar manner 1,4-[N(H)tBu]2BC6H4B[N(H)tBu]2 (3) is prepared in good yield by treatment of 1,4-Br2BC6H4BBr2 with five equivalents of [Li][N(H)tBu] in toluene. Compound 3 is converted to the highly air-sensitive tetralithio derivative [Li4][1,4-(NtBu)2BC6H4B(NtBu)2] (4), by deprotonation with nBuLi in hexanes. Alkali-metal derivatives of a monoanionic boraamidinate [M][PhB(NDipp){N(H)Dipp}] [M = Li (5), K (6)] are produced by reactions of PhB[N(H)Dipp]2 with one equivalent of nBuLi in hexanes or [K][CH2Ph] in THF, respectively. The use of two equivalents of [K][CH2Ph] generates the dipotassium reagent [K2][PhB(NDipp)2] (7) in excellent yield. The X-ray structures of 1a, 1b, 2, 4·6THF, 5·2THF and 7·3THF were determined. The complex 4·6THF incorporates one terminal and one bridging THF molecule for each Li+ cation. The boraamidinate ligand in 5·2THF is connected in an N-monodentate fashion to the Li+ cation, which is solvated by two THF molecules. In the solid state 7·3THF forms an extended structure as a result of η1-amide–η6-arene coordination to the two K+ cations, which are coordinated by one or two THF molecules, respectively.

Graphical abstract: Syntheses and structures of new alkali-metal boraamidinates and ferrocenyl aminoboranes
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