The chemistry of the group 2 metals (beryllium, magnesium, calcium, strontium, and barium) is dominated by the +2 oxidation state. Here, we report the reductions of two magnesium(II) iodide complexes with potassium metal in toluene, leading to thermally stable magnesium(I) compounds, (L)MgMg(L) (where L is [(Ar)NC(NPri2)N(Ar)]- or {[(Ar)NC(Me)]2CH}-, Ar is 2,6-diisopropylphenyl, Me is methyl, and Pri is isopropyl) in moderate yields. The results of x-ray crystallographic and theoretical studies are consistent with central Mg2+(2) units that have single, covalent magnesium-magnesium bonding interactions with 2.8508 +/- 0.0012 (standard deviation) and 2.8457 +/- 0.0008 angstrom bond lengths, respectively, and predominantly ionic interactions with the anionic ligands (L).

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The guanidinato- or amidinato-bridged diarsenes [As2{mu-(ArN)2CR}2] (Ar = C6H3Pri2-2,6; R = N(C6H11)2, NPri2, or But) have been prepared by reduction of the corresponding As(III) precursors, [Cl2As{kappa2-N,N'-(ArN)2CR}]. Theoretical studies suggest that the As-As bonds of the dimers have significant double-bond character, the sigma and pi components of which are derived mainly from As p orbital overlaps.

The odd couple: A dimeric magnesium(I) complex acts as a facile and selective two-center/two-electron reductant towards a series of unsaturated substrates (see scheme; Ar = 2,6-iPr(2)C(6)H(3), Ad = 1-adamantyl). The novel reduced or reductively coupled products obtained from these reductions suggest that magnesium(I) compounds may find wide use in organic and organometallic syntheses.

Reactions of the anionic gallium(I) heterocycle [:Ga{[N(Ar)C(H)] 2 }] -(Ar ) C 6 H 3 Pr i 2 -2,6) with a variety of N-heterocyclic carbene (NHC) complexes of group 9 and 11 halides are reported. In all cases, salt elimination occurs, yielding the neutral metal gallyl complexes). NHC coordination apparently stabilizes the formed complexes toward elimination processes that have been observed in previous studies. The majority of the complexes in this study have been the subjects of X-ray crystallographic studies, which in several cases reveal the first examples of Ga-Cu or Ga-Ag bonds in molecular complexes. Analogies between the gallium heterocycle and cyclic boryl ligands are explored. Solid-state and spectroscopic studies on the prepared complexes suggest that the gallyl ligand has a trans influence intermediate between cyclic boryls and chloride.

The reactions of the anionic gallium(I) N-heterocyclic carbene (NHC) analogue, [K(tmeda)][:Ga{[N(Ar)C(H)]2}], Ar = C6H3Pri2-2,6, with the heavier group 14 alkene analogues, R2E=ER2, E = Ge or Sn, R = -CH(SiMe3)2, have been carried out. In 2:1 stoichiometries, these lead to the ionic [K(tmeda)][R2EGa{[N(Ar)C(H)]2}] complexes which exhibit long E-Ga bonds. The nature of these bonds has been probed by DFT calculations, and the complexes have been compared to neutral NHC adducts of group 14 dialkyls. The 4:1 reaction of [K(tmeda)][:Ga{[N(Ar)C(H)]2}] with R2Sn=SnR2 leads to the digallyl stannate complex, [K(tmeda)][RSn[Ga{[N(Ar)C(H)]2}]2], presumably via elimination of KR. In contrast, the reaction of the gallium heterocycle with PbR2 affords the digallane4, [Ga{[N(Ar)C(H)]2}]2, via an oxidative coupling reaction. For sake of comparison, the reactions of [K(tmeda)][:Ga{[N(Ar)C(H)]2}] with Ar'2E=EAr'2, E = Ge, Sn or Pb, Ar' = C6H2Pri3-2,4,6, were carried out and led to either no reaction (E = Ge), the formation of [K(tmeda)][Ar'2SnGa{[N(Ar)C(H)]2}] (E = Sn), or the gallium(III) heterocycle, [Ar'Ga{[N(Ar)C(H)]2}] (E = Pb). Salt elimination reactions between [K(tmeda)][:Ga{[N(Ar)C(H)]2}] and the guanidinato group 14 complexes [(Giso)ECl], E = Ge or Sn, Giso = [Pri2NC{N(Ar)}2]-, gave the neutral [(Giso)EGa{[N(Ar)C(H)]2}] complexes. All complexes have been characterized by NMR spectroscopy and X-ray crystallographic studies.

Vielseitig reduzierend: Ein dimerer Magnesium(I)‐Komplex wirkt als ein selektives Zweizentren‐Zweielektronen‐Reduktionsmittel gegenüber einer Serie von ungesättigten Substraten (siehe Schema; Ar=2,6‐iPr2C6H3, Ad=1‐Adamantyl). Die neuartigen reduzierten oder reduktiv gekuppelten Produkte stellen eine weite Verbreitung von Magnesium(I)‐Verbindungen in organischen und metallorganischen Synthesen in Aussicht.

A series of complexes between recently developed four-membered group 13 metal(I) heterocycles and group 10 metal(0) fragments have been prepared and structurally characterized. One prepared complex, [Pt{Ga[N(Ar)]2CNCy2}3] (Ar = C6H3Pri2-2,6; Cy = cyclohexyl), possesses the shortest Pt-Ga bonds yet reported, the covalent components of which are suggested by theoretical studies to have significant pi character.