Substituent effects on stability (assumed as the singlet and triplet energy gaps, ΔΕ) of novel 1,4-disubstituted-tetrazole-5-vinylidene germylenes (normal, 1) and their corresponding 1,3-disubstituted-tetrazole-5-vinylidene germylenes (abnormal, 2) are computed and compared, at B3LYP/6-311++G** and M06/6-311++G**, where R = H, CN, CF, F, SH, CH, OMe, and OH. Interestingly, every triplet vinylidene germylene shows more stability than its corresponding singlet. Also, every triplet abnormal isomer (2) emerges to be more stable than its corresponding normal (1). All abnormal 2 isomers show broader band gaps (ΔE) and higher nucleophilicity (N), but less electrophilicity (ω) than their corresponding normal 1 isomers. The NICS (nuclear-independent chemical shift) results indicate that every 1 (except singlet 2) emerges more aromatic than its corresponding 2. Our Hammet studies indicate that 1 is more sensitive to the electronic effects of substituents, R, than 2. Electron-donating species increase N in both 1 and 2, while electron-withdrawing groups increase stability.
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http://dx.doi.org/10.1007/s00894-019-4213-2 | DOI Listing |
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