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 ), wh ich re act s in sit u wit h K-(C 5 H 4 CH 2 CH 2 NMe 2 ) (KCp Do ) or K(OCH 2 CH 2 NMe 2 ) (KOR Do ) to produce the monomeric species (dpp-Bian)-GaCp Do (3) and (dpp-Bian)GaOR Do (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(S 2 CNMe 2 ) (6) reacts with PhCCH and HCCH to give the cycloaddition products [dpp-Bian(PhC CH)]Ga(S 2 CNMe 2 ) ( 7) and [dpp-Bian(HCCH)]Ga(S 2 CNMe 2 ) (8). The related compounds [dpp-Bian(MeCCC(O)-OMe)]Ga(S 2 CNMe 2 ) ( 9) and [dpp-Bian(CH 2 CHC(Me)O)]Ga(S 2 CNMe 2 ) (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 1 H 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.

Cycloaddition versus Cleavage of the C=S Bond of Isothiocyanates Promoted by Digallane Compounds with Noninnocent α‐Diimine Ligands

“…The addition of unsaturated compounds to metal–organic rings containing transition and main group metals is known . Such compounds as Ar 2 C=O, O 2 ,, CH 2 =CHC(O)CH 3 , and Ph 2 C=C=O, form cycloadducts with main group metal–organic rings. The closest analogy to the discussed reactions with isothiocyanates is the addition of alkynes to metal complexes with neutral or dianionic α‐diimine ligands.…”

Redox‐Active Ligand‐Assisted Two‐Electron Oxidative Addition to Gallium(II)

“…In the search for a reductive elimination in the dpp‐bian gallium derivatives, we have studied the solution behavior of compounds 11 – 16 as well as complex (dpp‐bian)Ga(C≡CPh) 2 at high temperature. With the exception of complex 14 , all the compounds were stable in solution up to 130 °C and under UV irradiation.…”

Gallium “Shears” for C=N and C=O Bonds of Isocyanates

“…[2] In contrast, reactions in which a metal becomes part of ac ycle are rare. [19] Under reduction with sodium in THF,digallanes 1 and 2 generate carbene-like gallylenes 1A and 2A. [19] Under reduction with sodium in THF,digallanes 1 and 2 generate carbene-like gallylenes 1A and 2A.…”

“…[3] In 2009, Power and co-workersd isclosed additions of ethylene, norbornadiene, and 1,3,5,7-cyclooctatetraene to metallynes RMMR (M = Ge, Sn; gallium complexes, [L 1 AlEt(Et 2 O)] and [L 1 Ga(S 2 CNMe 2 )],r eact with alkynes and methyl vinyl ketone to give cycloadducts. [19] Under reduction with sodium in THF,digallanes 1 and 2 generate carbene-like gallylenes 1A and 2A. [12a, 13a, 20] Related gallium NHC analogues consisting of four-, five-, and six-membered metallacycles have also been reported.…”