Computational investigations into the potential use of poly(benzyl phenyl ether) dendrimers as supports for organometallic catalysts

We studied the structure and conformation of organic and organochromium poly(benzylphenyl ether) dendrimers (PBPE dendrimers) via atomistic molecular dynamics computer simulations. The results of our computational investigations show that the metal carbonyl centers are available to participate in chemical reactions. When the results of a course-grain computer simulation study by Murat and Grest(1) were used, this conclusion was valid for all solvent conditions. The terminal groups of both the organic and organochromium dendrimers smaller than generation 3 (g(max) less than or equal to 3) undergo significant backfolding and are capable of penetrating the central (core) region. However in the organochromium case, for g(max) > 3 the terminal ((benzyl)tricarbonylchromium(0)) groups do not penetrate the core region to the same extent as do the terminal (benzyl) groups in the organic dendrimers of similar generation. This is mainly due to molecular crowding. By calculating the fractal dimensions we are able to determine that both dendrimer types are compact structures. However, despite their compact nature the terminal groups of the later organochromium polymers are solvent accessible and hence spatially available to act as catalysts in chemical reactions.