A Valence Bond Analysis of Olefin Polymerization Catalysts

Timothy K. Firman and Tom Ziegler

Olefin Polymerization

Very important industrial processes Many non-metallocene catalysts have recently

been discovered A variety of d0 homogeneous catalysts are known,

as well as some which are d6, d7, or d8. A better understanding of the effects of changing

metal and ligands will lead to better catalysts

Second Row Transition Metals

Metal Euptake Einsertion Etermination

V (d1) 1 -24.6 +9.5 +14.1Cr (d2) 1 -20.1 +6.3 +13.2Mn (d3) 1 -13.7 +11.1 +17.5Mo (d2) -58.9 +25 +19.6Ru (d4) -38.9 +30 +31.0Pd (d6) -14.3 +19.3 +23.31Rochus Schmid and Tom Ziegler, submitted for publication

H2N

M

H2N

Addition of an Amine GroupH2N

M

H2N

H3N

H2N

M

H2N

Metal Euptake Einsertion Etermination

V(d1) 1 -24.6 +9.5 +14.1Cr(d2) 1 -20.1 +6.3 +13.2Mn(d3) 1 -13.7 +11.1 +17.5V(d1)+NH3 -3.0 +8.3 +16.4Cr(d2)+NH3 -5.2 +12.5 +19.6Mn(d3)+NH3 -5.4 +13.6 +20.0

Linked Ligands

NH

M

NH

HN

Electronically analogous to the previous modelEthyl bridges will restrict geometry, increasing uptake energy by lowering reorganization costs

LocalizedOrbitals

Olefin insertion

More Localized Orbitals

Chain Termination(via -hydride transfer)

Future Work

Analysis of amide/amine systems which include constraining ligands

Further investigation of electronic effects of ligands on transition state energies

Exploration of -conjugated ring ligands with variable ligand-metal bond order.

Acknowledgements

Tom Ziegler Rochus SchmidTom Gilbert Sergei Patchkovskii

The Ziegler Group

NSERC and Nova