Different alkynes add reversibly to the gallium complex of the dpp-Bian dianion. The reactions proceed with addition of the alkynes across the Ga-N-C fragment resulting in carbon-carbon and carbon-gallium bonds. In the case of 3 and 4 a full elimination of the alkyne takes place at T < 100 degrees C, whereas with adducts 5 and 6 it occurs at heating to ca. 200 degrees C.

The reactions of (dpp-bian)Mg(thf) 3 (1) {dpp-bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene} with 0.5 molar equivalents of RS-SR (R = Bz, sBu, C(S)NMe 2 ) occur with a cleavage of the S-S bond to afford monosulfide complexes (dpp-bian)Mg(SBz)(dme) (2), (dpp-bian)Mg[S(sBu)]-(dme) (3), and (dpp-bian)Mg[SC(S)NMe 2 ](thf) (4). Compounds 2, 3, and 4 are paramagnetic due to the presence of dpp-bian radical-anions that are formed in the course of oneelectron transfer from the dpp-bian dianion in 1 to the sulfurcontaining substrate. Reduction of BzS-SBz with gallane (dpp-bian)Ga-Ga(dpp-bian) (5) gives a mononuclear Ga III

Acetylene, phenylacetylene, and alkylbutynoates add reversibly to (dpp-bian)Ga-Ga(dpp-bian) (dpp-bian=1,2-bis[(2,6-diisopropylphenyl)-imino]acenaphthene) to give addition products [dpp-bian(R(1)C=CR(2))]Ga-Ga[(R(2)C=CR(1))dpp-bian]. The alkyne adds across the Ga-N-C section, which results in new carbon-carbon and carbon-gallium bonds. The adducts were characterized by electron absorption, IR, and (1)H NMR spectroscopy and their molecular structures have been determined by single-crystal X-ray analysis. According to the X-ray data, a change in the coordination number of gallium from three [in (dpp-bian)Ga-Ga(dpp-bian)] to four (in the adducts) results in elongation of the metal-metal bond by approximately 0.13 Å. The adducts undergo a facile alkynes elimination at elevated temperatures. The equilibrium between [dpp-bian(PhC=CH)]Ga-Ga[(HC=CPh)dpp-bian] and [(dpp-bian)Ga-Ga(dpp-bian) + 2 PhC≡CH] in toluene solution was studied by (1)H NMR spectroscopy. The equilibrium constants at various temperatures (298≤T≤323 K) were determined, from which the thermodynamic parameters for the phenylacetylene elimination were calculated (ΔG°=2.4 kJ mol(-1), ΔH°=46.0 kJ mol(-1), ΔS°=146.0 J K(-1) mol(-1)). The reactivity of (dpp-bian)Ga-Ga(dpp-bian) towards alkynes permits use as a catalyst for carbon-nitrogen and carbon-carbon bond-forming reactions. The bisgallium complex was found to be a highly effective catalyst for the hydroamination of phenylacetylene with anilines. For instance, with [(dpp-bian)Ga-Ga(dpp-bian)] (2 mol%) in benzene more than 99% conversion of PhNH(2) and PhC≡CH into PhN=C(Ph)CH(3) was achieved in 16 h at 90 °C. Under similar conditions, the reaction of 1-aminoanthracene with PhC≡CH catalyzed by (dpp-bian)Ga-Ga(dpp-bian) formed a carbon-carbon bond to afford 1-amino-2-(1-phenylvinyl)anthracene in 99% yield.

Molybdenum hexacarbonyl reacts with 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene (, dpp-BIAN) and 1,2-bis[(trimethylsilyl)imino]acenaphthene (, tms-BIAN) in toluene to produce (dpp-BIAN)Mo(CO)(4) () and (tms-BIAN)Mo(CO)(4) (), respectively. The reaction of [CpNi(CO)](2) with yields (dpp-BIAN)NiCp (). Metathesis between Li(2)(tms-BIAN) and NiCl(2)(dppe) affords the Ni(0) complex (tms-BIAN)Ni(dppe) (). The diamagnetic compounds , and have been characterized by (1)H, (29)Si and (31)P NMR spectroscopy, IR spectroscopy and elemental analysis. The ESR spectrum of the paramagnetic compound indicates the presence of Ni(i) coordinated by Cp and a neutral dpp-BIAN ligand. The molecular structures of have been determined by single-crystal X-ray analysis.

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