Reaction of disodium tetracarbonylferrate, Na2[Fe(CO)4], with [2,6-bis(2,4,6-triisopropylphenyl)phenyl]gallium dichloride, (Mes*2C6H3)GaCl2 (Mes* = 2,4,6-triisopropylphenyl), affords tetracarbonyliron [2,6-bis(2,4,6-triisopropylphenyl)phenyl]gallyne, (CO)4Fe⋮Ga(C6H3Mes*2), as anaerobically stable yellow prism crystals. The title compound offers evidence in support of an iron−gallium triple bondthe first ferrogallyne.

The cyclogallane dipotassium tris((2,6-dimesitylphenyl)cyclogallene), K 2 [(Mes 2 C 6 H 3 )Ga] 3 (Mes ) 2,4,6-Me 3 C 6 H 2 ), has been prepared by either of two distinct synthetic routes. Disproportionation of gallium(II) chloride, Ga 2 Cl 4 , in the presence of (2,6-dimesitylphenyl)lithium, (Mes 2 C 6 H 3 )Li, followed by potassium metal reduction in Et 2 O affords the title compound as large ruby red crystals. Alternatively, K 2 [(Mes 2 C 6 H 3 )Ga] 3 may readily be approached by direct alkali metal reduction of (Mes 2 C 6 H 3 )GaCl 2 . The title compound was characterized by 1 H and 13 C NMR, elemental analyses, IR spectroscopy, and single-crystal X-ray diffraction. The cyclogallane resides about the planar Ga 3 triangle constituted by extremely short Ga-Ga bonds: 2.4260(5), 2.4317(5), and 2.4187(5) Å. Theoretical examination of the Ga 3 2anionic core in [GaH] 3 2-, Na 2 [GaH] 3 , and K 2 [GaH] 3 suggests a well-defined π-molecular orbital. Both experimental and theoretical results strongly support the cyclogallene dianion, [(Mes 2 C 6 H 3 )Ga] 3 2-, as a well-defined metalloaromatic systemsa metallic ring system exhibiting aromatic behavior.

Reaction of gallium chloride with (2,6-dimesitylphenyl)lithium, (Mes2C6H3)Li (Mes = 2,4,6-Me3C6H2), gives bis[(dimesitylphenyl)gallium dichloride], [(Mes2C6H3)GaCl2]2, I. Treatment of I with {2-[(dimethylamino)methyl]phenyl}lithium, [2-(Me2NCH2)C6H4]Li, affords (dimesitylphenyl)-2-((dimethylamino)methyl)phenylgallium chloride, (Mes2C6H3)[2-(Me2NCH2)C6H4]GaCl, II. Reaction of (Mes2C6H3)Li with gallium bromide affords bis(dimesitylphenyl)gallium bromide, (Mes2C6H3)2GaBr, III, while reaction of I with (Mes)Li yields (dimesitylphenyl)dimesitylgallium, (Mes2C6H3)(Mes)2Ga, IV. Gallium aryls I − IV have been characterized by elemental analyses, 1H and 13C NMR and IR spectroscopies, and single-crystal X-ray diffraction. I assumes a μ2-chloro-bridged dimeric structure, while the coordination of gallium in II is completed by one Mes2C6H3 ligand and one chloride ligand and is intramolecularly stabilized by the nitrogen atom of [2-(Me2NCH2)C6H4]. III assumes a rare T-shaped coordination about the gallium center (C−Ga−C 153.5(2)°), while IV represents, arguably, the most sterically crowded trigonal planar gallium aryl reported with the aromatic rings about the GaC3 plane approaching 90°.

(2,6-Diphenylphenyl)lithium−bis(diethyl ether), Ph2C6H3Li·2Et2O (I), was synthesized by reaction of n-butyllithium with 2,6-diphenyl-1-iodobenzene in diethyl ether. Reaction of I with group 13 metal halides, MX3 (M = Ga, X = Cl, I; M = In, X = Cl), affords bis(2,6-diphenylphenyl)gallium iodide, (Ph2C6H3)2GaI (II), bis(2,6-diphenylphenyl)indium chloride, (Ph2C6H3)2InCl (III), and bis(diethyl ether)lithium trichloro-2,6-diphenylphenylgallate, [Li·2Et2O][Ph2C6H3GaCl3] (IV). Reaction of (2,4,6-triphenylphenyl)lithium with GaCl3 gives (diethyl ether)lithium trichloro(2,4,6-triphenylphenyl)gallate, [Li·Et2O][Ph3C6H2GaCl3] (V). The group 13 metal aryls were characterized by 1H and 13C NMR spectroscopy, elemental analyses, and single-crystal X-ray diffraction. The neutral lithium aryl (I) and arylgallium halide species (II) exhibit trigonal-planar coordination, while the coordination of the gallium atoms in anions IV and V assume distorted-tetrahedral conformations.