Group 2 and 12 Metal Gallyl Complexes Containing Unsupported Ga−M Covalent Bonds (M = Mg, Ca, Sr, Ba, Zn, Cd)

Reactions of the anionic gallium(I) heterocycle [:Ga(DAB)]− (DAB = {N(Dip)C(H)}2, Dip = C6H3Pri2-2,6) with several group 2
and 12 metal halide complexes are reported. Treatment of in situ generated
[MI2(tmeda)n] (M = Ca, Sr,
Ba; tmeda = N,N,N′,N′-tetramethylethylenediamine) with
2 equiv of [K(tmeda)][:Ga(DAB)] leads to salt elimination and formation
of the neutral metal gallyl complexes trans-[M{Ga(DAB)}2(tmeda)2]. Reaction of [(Nacnac)MgI(OEt2)] (Nanac = {N(Dip)C(Me)}2CH) with [K(tmeda)][:Ga(DAB)]
gives [(Nacnac)(κ1-tmeda)Mg{Ga(DAB)}]. All complexes
were crystallographically characterized and display isomerism in solution,
which for the latter compound has been investigated by variable-temperature
NMR spectroscopy. The 1:1 reactions of [K(tmeda)][:Ga(DAB)] with [MX2(tmeda)] (M = Zn, X = Br; M = Cd, X = I) yield [(tmeda)MX{Ga(DAB)}],
the cadmium example of which is the first molecular complex bearing
a Ga−Cd bond. Attempts to reduce these compounds to low-valent
species, e.g. [{(DAB)Ga}MM{Ga(DAB)}], were unsuccessful. Treating
[(Nacnac)Zn(μ-Br)2Li(OEt2)2] with [K(tmeda)][:Ga(DAB)] gave [(Nacnac)Zn{Ga(DAB)}], the X-ray
crystal structure of which is reported.

本文报道了阴离子型一价镓杂环[:Ga(DAB)]⁻（其中DAB = {N(Dip)C(H)}₂，Dip = 2,6-二异丙基苯基(C₆H₃Pri₂-2,6)）与数种第2族及第12族金属卤化物配合物的反应。将原位生成的[MI₂(tmeda)ₙ]（M = Ca、Sr、Ba；tmeda = N,N,N′,N′-四甲基乙二胺(N,N,N′,N′-tetramethylethylenediamine)）与2当量的[K(tmeda)][:Ga(DAB)]进行反应，可通过消除成盐反应得到中性金属镓基配合物反式-[M{Ga(DAB)}₂(tmeda)₂]。将[(Nacnac)MgI(OEt₂)]（Nacnac = {N(Dip)C(Me)}₂CH）与[K(tmeda)][:Ga(DAB)]反应，可得到[(Nacnac)(κ¹-tmeda)Mg{Ga(DAB)}]。所有配合物均经晶体学表征，且在溶液中表现出异构现象；其中后述化合物的异构行为已通过变温核磁共振波谱法进行了研究。将[K(tmeda)][:Ga(DAB)]与[MX₂(tmeda)]（M = Zn、X = Br；M = Cd、X = I）以1:1摩尔比反应，可得到[(tmeda)MX{Ga(DAB)}]，其中镉类配合物是首例含Ga-Cd键的分子配合物。尝试将这类化合物还原为低价态物种（如[{(DAB)Ga}MM{Ga(DAB)}]）均未获成功。将[(Nacnac)Zn(μ-Br)₂Li(OEt₂)₂]与[K(tmeda)][:Ga(DAB)]反应，得到[(Nacnac)Zn{Ga(DAB)}]，本文报道了该配合物的X射线晶体结构。