Mononuclear dpp-Bian Gallium Complexes: Synthesis, Crystal Structures, and Reactivity toward Alkynes and Enones

Abstract

Treatment of (dpp-Bian)Ga–Ga(dpp-Bian) (1) (dpp-Bian = 1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with iodine gives (dpp-Bian)Ga(I)–Ga(I)(dpp-Bian) (2), which reacts in situ with K(C5H4CH2CH2NMe2) (KCpDo) or K(OCH2CH2NMe2) (KORDo) to produce the monomeric species (dpp-Bian)GaCpDo (3) and (dpp-Bian)GaORDo (4), respectively. Complex 3 reacts with PhC≡CH to give the paramagnetic derivative (dpp-Bian)Ga(C≡CPh)2 (5), while compound 4 is inert toward this alkyne. In contrast, monomeric (dpp-Bian)Ga(S2CNMe2) (6) reacts with PhC≡CH and HC≡CH to give the cycloaddition products [dpp-Bian(PhC═CH)]Ga(S2CNMe2) (7) and [dpp-Bian(HC═CH)]Ga(S2CNMe2) (8). The related compounds [dpp-Bian(MeC═CC(O)OMe)]Ga(S2CNMe2) (9) and [dpp-Bian(CH2CH═C(Me)O)]Ga(S2CNMe2) (10) have been obtained in the reactions of complex 6 with methyl 2-butynoate and methyl vinyl ketone, respectively. New complexes have been characterized by 1H NMR (3, 4, and 7–10) and ESR (5) spectroscopy; their molecular structures have been established by single-crystal X-ray analysis. The catalytic activity of complex 6 in the hydroamination and hydroarylation of alkynes has been examined.