苯型稠环分子共轭效应的定量序列

The Quantitative Sequence of Conjugative Effect of the Even Benzenoid Hydrocarbons

按Longuet-Higgins法算得了37种苯型稠环烃分子的电荷密度分布、并通过环上净获电荷(l-q)与电子吸收光谱;电离电位:极谱氧化及还原半波电位;电子亲力;每个电子的共振能以及自由基亲力等七种分子整体性,以及芳基常数σ_r间的良好线性关系表明(l-q)可用来定量表征各笨型稠环分子中共轭效应的相对大小.

Because of the extent of the charge density which originally localized on the out-of-ring atom of a benzenoid alternate hydrocarbon anion, cation and/or free radical delocalized to the arene nuclei is determined entirely to the power of conjugative effect exerted itself, as shown in Fig. 1. So the release part of the charge density(1-q)conld be used as a scale to arrange the benzenoid arenes in turn according to their power of conjugative effect, and it has been shown that the(1-q)correlates better than corresponding E(N-V_1)with Chiang's factor of homologous series. Since the letter is a very well structural parameter, the(1-q)might be even more precise than E(N-V_1), thongh they are all derived from simple HMO approach. In this paper, the(1-q)of 37 even benzenoid arenes has heen calculated, and it is found that the following linear correlationship is well comformed, in which p is spectra;P=A(1-q)+B electron affinity; polargraphic reductive and/or oxidative half wave potentials; resonance energy per electron; ionization potential; as well as metyl and or trichloromethyl affinity etc., Besides,(1-q)correlates with moderate accuracy to the σ_(?). So it might also be utilized to correlate the reactivity of the side chain reaction.