Computational analyses of the tris(3,4‐dimethylenecyclobuteno)benzene molecule indicate that the absence of the equivalent of a HOMO of an etheno group between the internal carbon atoms of the annelating butadieno groups is mainly responsible for the relatively weak cyclohexatriene‐like fixation in the central benzene ring. To increase the extent of C–C bond‐length alternation in the benzene moiety, two strategies of modification of the annelating groups are proposed to make the presence of the equivalent of a HOMO of an etheno group between the internal carbon atoms of the annelating butadieno groups. The first is to introduce a π‐electron‐donating heteroatom/group to form a five‐membered ring with the annelating butadieno groups (model I). The extent of bond‐length alternation could be tuned by the choice of the heteroatom/group in model I. The second is to coordinate with transition‐metal groups, such as the irontricarbonyl groups, for the annelating butadieno groups (model II). Computational results predict that molecules generated by using these two strategies could form strong cyclohexatriene‐like fixation of the double bonds in the central benzene ring.

Abstract-The purpose of this paper is to study the assessment method of carbon emission value. Firstly I introduce the traditional evaluation methods in the process, which are market method, income method and cost method. Then I analyze the applicability of those methods by combining the carbon emission value. As a result, these methods all have some limitations. So I propose a new method-evaluation model of gray system theory. The innovation of this paper lies in proposing a more suitable method to evaluate the carbon emission value.