N-H and N=C Bond Formation via Germanium(III) Diradicaloid Intermediates and C-S Bond Cleavage in Reactions of the Digermyne Ar′GeGeAr′ (Ar′ = C6H3-2,6-(C6H3-2,6-Pri2)2) with Azides

Reactions of the digermyne Ar'GeGeAr' (Ar' = C6H3-2,6(C6H3-2,6-Pr-2(i))(2)) (1) with four different azides R'N-3 (R = Me3Sn, (Bu3Sn)-Bu-n, PhSCH2, or 1-adamantanyl) are described. Treatment of 1 with Me3SnN3 or (Bu3SnN3)-Bu-n afforded the low-valent germanium (II) parent amido derivative, Ar'Ge(mu(2)-NH2)(2)GeAr' (3) or the high-valent germanium (IV) parent imido derivative, Ar'((Bu3Sn)-Bu-n)Ge(mu(2)-NH)(2)Ge((SnBu3)-Bu-n)Ar' (4), respectively. Addition of AdN(3) (Ad = 1-admantanyl) yielded a monoimide bridged species Ar'Ge(mu(2)-NAd)GeAr' (5). The structure of 5 differs from that of the diradicaloid Ar'Ge(mu(2)-NSiMe3)(2)GeAr' (2), which was previously obtained from the analogous reaction of 1 with Me3SiN3. The reaction of 1 with PhSCH2N3 afforded the germanium ketimide Ar'Ge(SPh)(2)(N=CH2) (6) containing the imino -N=CH2 functional group. These reactions demonstrate a remarkable product dependence on the azide substituent. All compounds were spectroscopically and structurally characterized. Both 3 and 4 feature a four-membered Ge2N2 core. The structure of 5 is stabilized by CH-T interactions while 6 features a rare example of a interaction between an aromatic ring and a non-aromatic double bond (N=C). The mechanism of formation of 3-6 are discussed. It is proposed that 3 and 4 are obtained via diradical imido intermediates followed by H-abstraction from solvents, whereas 6 was formed by the activation of azide group in concert with C-S bond cleavage.