Synthesis and Study of Non-Kekule Molecules

这项提案要求提供资金，用化学和光谱方法研究一系列不相交的双自由基。分子轨道计算预测，不相交的双自由基将具有单重态基态。这个实验室以前的工作已经发现了一个三重基态不相交的双自由基。为了与理论计算进行比较，我们将用具有严格定义的结构的新例子来进一步探讨这一理论上的矛盾。我们将探索非交替的双自由基，它们以某种方式含有环戊二烯环。将探索这些双基的结构和多重性之间的相互作用，其中低元系有望是单一元系，而高元系是三元系。来自有机动力学项目的这笔赠款支持匹兹堡大学保罗·多德教授的继续工作。我们将研究一系列称为双自由基的新型活性中间体的化学和光谱性质。双自由基是两个位置上有奇数个电子的分子。例如，在碳氢双基中，两个碳原子将分别与另外三个碳原子成键，并有一个未成键的电子。这两个奇数电子的自旋可能是成对的(单态)，也可能是不成对的(三态)。双自由基的最低能态(单重态或三重态)将作为结构的函数通过实验确定。这些结果将与理论计算进行比较。

This proposal requests funds to examine a series of disjoint biradicals by chemical and spectroscopic methods. Molecular orbital calculations have predicted that disjoint biradicals will possess a singlet ground state. Previous work from this laboratory has resulted in finding a triplet ground state disjoint biradical. This contradiction of theory will be pursued further with new examples which have rigidly defined structures for comparison to theoretical calculations. Non-alternant biradicals will be explored, which contain in some fashion, cyclopentadiene rings. The interplay between structure and multiplicity of these biradicals will be explored, where lower membered systems are expected to be singlets and higher membered systems triplets. This grant from the Organic Dynamics Program supports the continuing work of Professor Paul Dowd at the University of Pittsburgh. The chemical and spectroscopic properties of a novel series of reactive intermediates known as biradicals will be examined. Biradicals are molecules where there are an odd number of electron at two sites. For example, in a hydrocarbon biradical, two carbon atoms will each be bonded to three other carbon atoms and have one unbonded electron. The two odd electrons may have spins paired (a singlet) or unpaired (a triplet). The lowest energy states (singlet or triplet) of the biradicals will be determined experimentally as a function of structure. These results will be compared to theoretical calculations.