Studies of Structure and Conformation Using NMR Spectroscopyand X-Ray Crystallography

该研究包括四个部分：(1)环丙基共轭的核磁共振研究，用于比较三元环、双键和苯基的给电子能力，以及有望证明带负电荷的二价磷可以作为有效电子给体的研究；(2)硫脲类化合物结构和动力学的二维核磁共振研究，旨在阐明构象平衡和缔合现象；(3)具有两个金属原子的新型有机金属化合物的合成和X射线结构测定，其中两个金属原子通过一个配体连接到一个金属上作为-芳烃配体，并通过一对孤电子连接到第二个配体上；(4)在含有金属氧基的第6族元素上形成金属碳键；新合成的配合物有望表现出氧基和烷基之间的相互作用，并且存在氧转移到烷基配体的可能性。这四个项目将广泛使用核磁共振光谱和X射线结晶学。多核变温一维和二维核磁共振实验将能够分析有机和有机金属化合物的交换、结构和构象。此外，合成的有机金属络合物的结构将通过X射线结晶学进行确定。这些项目将为少数民族学生提供使用这两种结构分配方法的经验和构象以及在化学和磁化交换的研究中。

The proposed research consists of four parts, as follows: (1) NMR studies of cyclopropyl conjugation, for comparing the - donating abilities of the three-membered ring, double bond, and phenyl group; also studies expected to show that negatively-charged divalent phosphorus can be an effective -electron donor; (2) 2-D NMR studies of structure and dynamics for thioureas aimed at elucidating conformational equilibria and associative phenomena; (3) Synthesis and X-ray structural determination of novel organometallic compounds having two metal atoms joined by a ligand attached to one metal as a -arene ligand, and attached to the second ligand by a lone pair of electrons; (4) Formation of metal-carbon bonds on group 6 elements containing metal-oxo groups; the newly synthesized complexes are expected to show an interaction between the oxo and alkyl groups and a possibility exists of a transfer reaction of oxygen to an alkyl ligand. The four projects will make extensive use of NMR spectroscopy and X-ray crystallography. Multinuclear variable temperature one- and two-dimensional NMR experiments will allow analysis of exchange, structure and conformations of organic and organometallic compounds. In addition, the structure of the organometallic complexes synthesized will be determined by X-ray crystallography. The projects will provide minority students with experience in using both methods of assigning structure and conformation and in the study of chemical and magnetization exchange.//