The syntheses and molecular structures of four compounds are reported:  1 (RBBr3), 2 (R(H)2B−B(H)2R), 3 (R(H)BB(H)R), and 4 (RBH3) (R = :C{N(2,6-Pr i 2C6H3)CH}2). These compounds were characterized by single-crystal X-ray diffraction, 1H and 11B NMR, and elemental analyses. Compounds 2 and 3 were prepared by the KC8 reduction of 1 in Et2O. Compound 3 is the first structurally characterized neutral diborene (mean BB:  1.560(18) Å). The nature of the BB double bond in 3 was delineated by DFT computations.

No abstract

Potassium reduction of RZn(mu-I)2Li(OEt2)2 (R = [{(2,6-Pri2C6H3)N(Me)C}2CH]) affords the second compound with a Zn-Zn bond, RZn-ZnR. The air- and moisture-sensitive title compound was characterized by 1H NMR, elemental analyses, and single-crystal X-ray diffraction. The Zn-Zn bond was determined to be 2.3586(7) A; this value is only about 0.05 A longer than the Zn-Zn bond reported for Cp*Zn-ZnCp* (Cp* = C5Me5), the first reported compound with a Zn-Zn bond. In addition, density functional theory (DFT) computations on related model RZn-ZnR compounds provide insight into the intriguing Zn-Zn bond.

The reaction of N-heterocyclic carbene, L:, with BeCl(2) quantitatively yields L:BeCl(2)1 (L: = :C{N(2,6-Pr(i)(2)C(6)H(3))CH}(2)). The carbene-stabilized beryllium borohydride monomer L:Be(BH(4))(2)2 is prepared by the reaction of 1 with LiBH(4). Compound 3, prepared by the reaction of 2 with Na(2)[Fe(CO)(4)]·dioxane, represents an unusual "dual reduction" of the imidazole ring (i.e., hydroboration of the C═C backbone and hydrogenation of the C2 carbene center).

Potassium graphite reduction of L:Ga(Mes)Cl(2) [L: = :C{(i-Pr)NC(Me)}(2), Mes = 2,4,6-Me(3)C(6)H(2)] (1) in hexane yields the organogallium dimer L:(Mes)(Cl)Ga-Ga(Cl)(Mes):L (2), while potassium reduction of 1 in toluene affords the neutral aromatic Ga(6) octahedron L:Ga[Ga(4)Mes(4)]Ga:L (3).