Synthesis and Characterization of Rigid Ditopic N-Heterocyclic Benzobisgermylenes and -stannylenes

A rigid ditopic benzobisgermylene, 4a, was
prepared by the reaction of the 1,2,4,5-tetra(alkylamine)­benzene 3a and Ge­[N­(SiMe3)2]2. The
analogous reaction of two 1,2,4,5-tetra(alkylamine)­­benzenes, 3b,c, with Sn­[N­(SiMe3)2]2 led to the oxidation of the tetramine ligand and formation
of N-alkyl-2-(alkylamine)-N′-alkyl-5-(alkylamine)-1,4-benzoquinonediimines (5b,c) and tin(0). The p-benzoquinonediimines 5b,c subsequently react with remaining Sn­[N­(SiMe3)2]2 to yield distannylene complexes
of type [N-alkyl-2-(alkylamino)-N′-alkyl-5-(alkylamino)-1,4-benzoquinonediimine]­di­[bis­(trimethylsilyl)­aminotin­(II)]
(6b,c). The 2,5-di­(alkylamine)-1,4-benzoquinonediimines 5b,c can also be obtained directly by aerial
oxidation of the 1,2,4,5-tetrakis­(alkylamine)­benzenes 3b,c. They react with two equivalents of Sn­[N­(SiMe3)2]2 also under transmetalation and
formation of [N-alkyl-2-(alkylamino)-N′-alkyl-5-(alkylamino)-1,4-benzoquinonediimine]­di­[bis­(trimethylsilyl)­aminotin­(II)]
(6b,c). The molecular structures of 3b, 4a, 6b, and 6c have
been established by X-ray diffraction.