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-Pr(i)2)2) with azides.
Reactions of the digermyne Ar'GeGeAr' (Ar' = C(6)H(3)-2,6(C(6)H(3)-2,6-Pr(i)(2))(2)) (1) with four different azides R'N(3) (R = Me(3)Sn, (n)Bu(3)Sn, PhSCH(2), or 1-adamantanyl) are described. Treatment of 1 with Me(3)SnN(3) or (n)Bu(3)SnN(3) afforded the low-valent germanium (II) parent amido derivative, Ar'Ge(mu(2)-NH(2))(2)GeAr' (3) or the high-valent germanium (IV) parent imido derivative, Ar'((n)Bu(3)Sn)Ge(mu(2)-NH)(2)Ge(Sn(n)Bu(3))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)-NSiMe(3))(2)GeAr' (2), which was previously obtained from the analogous reaction of 1 with Me(3)SiN(3). The reaction of 1 with PhSCH(2)N(3) afforded the germanium ketimide Ar'Ge(SPh)(2)(N=CH(2)) (6) containing the imino -N=CH(2) 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 Ge(2)N(2) core. The structure of 5 is stabilized by CH-pi interactions while 6 features a rare example of a pi-pi 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.
Wang
Xinping
X
Department of Chemistry, University of California, Davis, One Shields Avenue, California 95616, USA.
Ni
Chengbao
C
Zhu
Zhongliang
Z
Fettinger
James C
JC
Power
Philip P
PP