Electronic and steric effects on singlet and triplet symmetric 2,4-diX-vinylidenes with acyclic, cyclic-saturated, and cyclic-unsaturated structures are compared and contrasted with their corresponding asymmetric 2,5-diX-vinylidenes, at B3LYP/6-311++G** level of theory (X = H, Me, i-Pr, t-Bu, NH₂, OH, OMe, SH, Ph, CN, and CF₃). From 64 novel vinylidenes scrutinized, 45 are singlet while the other 19 show triplet ground state. These are suggested by the conductor like polarizable continuum model on both gas-phase and solvent-phase optimized structures. Regardless of X, band gap decreases in going from acyclic to cyclic-saturated and cyclic-unsaturated structures. More importantly nucleophilicity decreases with the same trend for symmetric carbenes. The proton affinity decreases in going from acyclic to cyclic-unsaturated and to cyclic-saturated structures for both symmetric and asymmetric carbenes. Atoms in molecules wavefunction analysis show internal hydrogen bondings for 1_s-Me, 1_s-i-Pr, 1_s-t-Bu, 1_s-Ph, 1′_s-CF3, 2_s-OH, 2′_s-t-Bu, and 2′_s-OMe.

在B3LYP / 6-311上，比较了具有单环，环饱和和环不饱和结构的单线和三线对称2,4-diX-亚乙烯基的电子和空间效应，并将其与相应的不对称2,5-diX-亚乙烯基进行了对比。 ++ G **理论水平（X = H，Me，i -Pr，t -Bu，NH ₂，OH，OMe，SH，Ph，CN和CF ₃）。从64个被审查的新型亚乙烯基中，有45个是单重态，而其他19个表现出三重态基态。气相和溶剂相优化结构上的导体（如可极化连续体模型）提出了这些建议。无论X如何，带隙都会从非环状结构变为环状饱和和环状不饱和结构。更重要的是，对称卡宾的亲核性下降趋势相同。对于对称和不对称碳烯，质子亲和力从无环结构变为环状不饱和结构，然后变为环状饱和结构。分子波函数分析中的原子显示1 _s-Me，1 _{s- i -Pr}，1 _{s- t -Bu的}内部氢键，1个_S-博士，1' _{S-CF 3}，2个_S-OH，2' _S-吨-Bu，和2' _S-OME。