Date of Award
Doctor of Philosophy
The catalytic properties of Ni(O) and Rh(I) complexes in the isomerization, hydrocyanation and hydrogenation of olefins have been investigated as a function of the steric and electronic properties of phosphite ester ligands. Studies done on the electronic differences between acyclic, monocyclic and bicyclic phosphite esters (Part I) were used to explain the differences in catalytic properties of the complexes of the various phosphites (Parts II, III and IV);Superior catalytic activities in olefin isomerization and hydrocyanation were shown by NiL(,4) complexes of the 4,6-disubstituted phosphorinanes compared to the NiL(,4) complexes of the unsubstituted and 5,5-disubstituted phosphorinanes, acyclic phosphites, five-membered monocyclic phosphites and bicyclic phosphites. This property has been attributed to optimum steric effects in NiL(,4) complexes of the 4,6-disubstituted phosphorinanes for ligand dissociation and coordination of olefins. The observed inactivity of the NiL(,4) complexes of the bicyclic phosphites and five-membered monocyclic phosphites has been attributed to the poor basicity of such phosphites and hence, of their NiL(,4) complexes. In addition to the strong protic acids F(,3)CCOOH and Cl(,3)CCOOH, Lewis acids such as AlCl(,3), ZnCl(,2) and TiCl(,3) were found to act as cocatalysts with NiL(,4) complexes in the isomerization and hydrocyanation of olefins. The optimum excess ligand to complex ratio for maximum rate of hydrocyanation of norbornene by the NiL(,4)/ZnCl(,2) systems was found to vary with L and is higher, the higher the maximum rate of catalysis of a complex. Attempts at asymmetric isomerization, hydrocyanation and hydrogenation of olefins using NiL(,4) and Rh(COD)L(,2)PF(,6) (L = asymmetric monocyclic and bicyclic phosphites) produced moderate optical yields.
Digital Repository @ Iowa State University, http://lib.dr.iastate.edu/
Gultneh, Yilma, "Effects of constraint on the catalytic properties of transition metal complexes of phosphite esters " (1981). Retrospective Theses and Dissertations. 7423.