The synthesis and characterization of the digermylenes [LGe-GeL] [L = L(1) (3A), L(2) (3B)] supported by the 2,6-diiminophenyl (L(1)) and 2-imino-5,6-methylenedioxylphenyl (L(2)) ligands are described. Their reactivities toward potassium graphite are also reported. The reaction of [LGeCl] [L = L(1) (2A), L(2) (2B)] with KC(8) in tetrahydrofuran (THF) at room temperature afforded the digermylenes [LGe-GeL] [L = L(1) (3A), L(2) (3B)], which are the first examples of diaryldigermylenes stabilized by o-imino donor(s). The treatment of 3A with 2 equiv of KC(8) in Et(2)O, followed by the addition of excess tetramethylethylenediamine (TMEDA), results in cleavage of the Ge(I)-Ge(I) bond to afford the germylidenide anion [L(1)GeK·TMEDA] (4A). Similarly, the reaction of 3B with excess KC(8) in THF afforded the germylidenide anion [L(2)GeK] (4B). The molecular structures of compounds 4A and 4B as determined by single-crystal X-ray diffraction analysis show that the K atoms are η(1)-coordinated with the low-valent Ge atoms. Moreover, the negative charges at the Ge atoms in compounds 4A and 4B are stabilized by electron delocalization in the germanium heterocycles.

The synthesis and characterization of the stannylidenide anion [LSn:]− (L = 2,6-(CHNBut)2C6H3) supported by the 2,6-diiminophenyl ligand is described. The reaction of the chlorostannylene [LSnCl] (2) with excess KC8 in diethyl ether at room temperature afforded the distannylene [LSn:]2 (3). The treatment of 3 with 2 equiv of KC8 in tetrahydrofuran (THF) resulted in the cleavage of the SnI–SnI bond in 3 to afford the potassium stannylidenide [LSnK·THF] (4). The molecular structure of compound 4 as determined by single-crystal X-ray diffraction analysis shows that the K atom is η5-coordinated to the low-valent tin heterocycle. Moreover, the negative charge at the Sn atom in compound 4 is stabilized by an electron delocalization in the low-valent tin heterocycle.

The two-electron reduction of a Group 14-element(I) complex [RË⋅] (E=Ge, R=supporting ligand) to form a novel low-valent dianion radical with the composition [RË:]˙(2-) is reported. The reaction of [LGeCl] (1, L=2,6-(CH=NAr)2C6H3, Ar=2,6-iPr2C6H3) with excess calcium in THF at room temperature afforded the germylidenediide dianion radical complex [LGe]˙(2-)⋅Ca(THF)3(2+) (2). The reaction proceeds through the formation of the germanium(I) radical [LGe⋅], which then undergoes a two-electron reduction with calcium to form 2. EPR spectroscopy, X-ray crystallography, and theoretical studies show that the germanium center in 2 has two lone pairs of electrons and the radical is delocalized over the germanium-containing heterocycle. In contrast, the magnesium derivative of the germylidendiide dianion radical is unstable and undergoes dimerization with concurrent dearomatization to form the germylidenide anion complex [C6H3-2-{C(H)=NAr}Ge-Mg-6-{C(H)-NAr}]2 (3).

The aromatic low‐valent lead analogue of an indenyl anion (see scheme; 1) undergoes oxidation with SnCl2 to form the base‐stabilized lead(I) dimer 2. Reduction of 2 with lithium regenerates 1. These compounds were characterized by NMR spectroscopy and X‐ray crystallography.

Aromatische niedervalente Blei‐Analoga eines Indenylanions (siehe Schema; 1) werden durch SnCl2 unter Bildung des basestabilisierten Blei(I)‐Dimers 2 oxidiert. Die Reduktion von 2 mit Lithium führt wieder zu 1. Beide Spezies wurden NMR‐spektroskopisch und Röntgen‐ kristallographisch charakterisiert.