Professor Werner Massa zum 60. Geburtstag gewidmet Inhaltsübersicht. Die vorsichtige Oxidation des tetraedrischen Tetragalliumclusters Ga 4 [C(SiMe 3 ) 3 ] 4 (1) mit elementarem Brom in Gegenwart von AlBr 3 führt zur Bildung des entsprechenden Subhalogenids Ga 2 Br 2 R 2 [4, R ϭ C(SiMe 3 ) 3 ], das überraschenderweise selbst im Festkörper monomer vorliegt und in dem die zweiwertigen Galliumatome über eine kurze Ga-Ga-Einfachbindung [243,2(2) pm] miteinander verbunden sind. Die analoge Digalliumdiiod-Verbindung Ga 2 I 2 R 2 (3), die bereits früher in unserer Arbeitsgruppe auf ähnlichem Weg erhalten wurde, reagiert mit Lithium-tert-butanolat nicht unter Substitution, sondern unter teilweiser Disproportionierung zu dem Trigalliumdiiodid Ga 3 I 2 R 3 (6), Abstract. The oxidation of the tetrahedral tetragallium cluster Ga 4 [C(SiMe 3 ) 3 ] 4 (1) with elemental bromine in the presence of AlBr 3 yielded the corresponding gallium subhalide Ga 2 Br 2 R 2 [4, R ϭ C(SiMe 3 ) 3 ], which remains monomer even in the solid state and in which the Ga II atoms are connected by a short Ga-Ga single bond [243.2(2) pm]. The analogous diiodide Ga 2 I 2 R 2 (3), which was obtained on a similar route by our group only recently, did not react with lithium tert-butanolate by substitution as originally expected. Instead, partial disproportionation occurred with the formation of the trigallium diiodide Ga 3 I 2 R 3 (6), in which three Ga atoms are connected by two Ga-Ga single bonds (255.1 pm on av-

The organoelement subhalides R2Ga2I2 (5) and R3In3I2 [6; R = C(SiMe3)3] reacted with silver benzoate AgOOCC6H5 to yield the dicarboxylato dielement compounds R2E2(µ‐OOCC6H5‐O,O′)2 (7, E = Ga; 8, E = In). Both compounds possess E−E single bonds bridged by the chelating carboxylato ligands. The chelating groups are arranged perpendicular to one another. Owing to the small bite of the carboxylato group very short E−E bond lengths of 240.5 pm (Ga−Ga) and 265.4 pm (In−In) were observed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

The organoelement subhalides R 2 Ga 2 I 2 (1) and [R 2 In 2 Cl 2 ] 2 (2) [R = C(SiMe 3 ) 3 ] react with silver acetylacetonate Ag(acac) (acac = [OC(CH 3 )] 2 CH) and lithium acetylacetonate Li(acac), respectively, to yield the di(acetylacetonato)dielement compounds R 2 E 2 (acac) 2 (3: E = Ga; 4: E = In). Both products possess E-E single bonds with relatively long E-E distances of 251.1 (Ga-Ga) and 278.0 pm (In-In). The gallium or indium atoms are terminally coordinated by an alkyl and a bidentate

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Keywords: Gallium / Subvalent compounds / Subhalides / Metal-metal bonds / Carboxylato ligands The organoelement subhalide R 2 Ga 2 I 2 (1) [R = C(SiMe 3 ) 3 ] reacted with one equivalent of different lithium carboxylates LiO 2 CR [R = -C 6 H 5 , -4-Me 3 C-C 6 H 4 , -4-BrC 6 H 4 , -3,5-Me 2 C 6 H 3 , -CMe 3 ] by the selective replacement of only one iodine atom. Bifunctional digallium compounds were formed, in which one chelating carboxylato group bridges the Ga-Ga bonds. Thus, both gallium atoms are coordinated to one car-