eta(1)- and eta(5)-indenyl and cyclopentadienyl tri-tert-butylphosphoraneiminatotitanium complexes

The compounds (indenyl)Ti(NP-t-Bu-3)Cl-2 (4), Cp2Ti(NP-t-Bu-3)Cl (6), (inde nyl)(2)Ti(NP-t-Bu-3)-Cl (7), Cp(indenyl)Ti(NP-t-Bu-3)Cl (8), Cp3Ti(NP-t-Bu- 3) (9), (indenyl)(3)Ti(NP-t-Bu-3) (10), and Cp(indenyl)(2)Ti(NP-t-Bu-3) (11 ) are readily derived from reaction with (dme)NaCp or Li-(indenyl) with CpT i(NP-t-Bu-3)Cl-2 (1) or 4 in the appropriate stoichiometry. X-ray crystallo grapby studies of (indenyl)Ti(NP-t-Bu-3)Me-2 (5) and 7-11 are reported. In the case of 6 and 9 two cyclopentadienyl rings are bound to the metal in a eta (5)-bonding mode, whereas in 7, 8, 10, and 11 one of the cyclopentadien yl or indenyl ligands is bound in an eta (5) mode and the remainder in an e ta (1)-fashion. In the case of 10, temperature-dependent H-1 NMR spectra in fer a eta (5)-eta (1) ligand exchange process with an approximate barrier o f 8-9 kcal/mol. Steric crowding appears to be the major factor determining the binding modes of the cyclopentadienyl and indenyl ligands. These struct ural data result in a view of the phosphoraneiminato ligand as a sterically demanding, four-electron donor ligand.