2-乙烯吡啶-丁烯酮共聚物及其羰基铑配合物的XPS研究

Study of 2-Vinylpyridine-Vinyl Methyl Ketone Copolymers and Their Carbonyl-Rhodium Complexes by XPS

本文用X-射线光电子能谱(XPS)研究了2-乙烯吡啶-丁烯酮共聚物及其与四羰基二氯二铑形成的配合物的结构特征.由反映在共聚物Cls光电子伴峰和(?)基Cls峰的消失,以及共聚物Nls和Ols结合能在配合物中的降低,即从施受两方面确证N→Rh和O→Rh配位键的形成.对催化性能的探讨表明,丁烯酮含量的增加导致催化活性的升高。

A series of linear copolymers of 2-vinylpridine(Y) and vinyl methyl ketone(D) with different compositions, as well as their complexes with tetracarbonyldichlorodirhodium (YDRh) have been prepared. Structrue characteristics of the complexes YDRh have been determined by X- ray photoelectron spectroscopy(XPS), and the influence of complex structures on their catalytic activity in carbonylation of methanol has been investigated. The shift, or phenomenally the disappearence or coalescence with others, of Cls peaks of copolymer carbonyl groups in the coordination complexes, the augmentation of binding energies of copolymer N1s and O1s, and the parallel reduction of Rh3d5/2 binding energies in the corresponding complexes, i. e. from the evidences of donor and acceptor be haviours, confirm the formation of N→ Rh and O→Rh coordination bonds, and demonstrate the existence of the two structural units in the complexes(see the schemes on p. 40). Experiments of methanol carbon''lation catalyzed by the complexes reveal that the reaction rate increases with the content of D-moncmer in copolymer ligands within a certain range, showing that the activity of the coordination unit-A is mch higher than B-unit's, which is , maybe, due to the weaker coordination linkage of O→Rh. In the A-units, the strong N→Rh bond is favorable to stabilize the complex and the weaker O→Rh linkage is easy to dissociate. Introducing the Rh-ion into the unsaturated state and promoting the oxidative addition of iodomethane to the cis-dicarbonylrhodium ( I )-ion active species, therefore, accelerate the catalytic reaction.