Structures and reactivity of Zr(IV) chlorobenzene complexes.
The synthesis, structures, and unusual reactivity of (C5R5)2ZrR'(ClPh)+ chlorobenzene complexes are described. The reaction of (C5R5)2ZrR'2 with [Ph3C][B(C6F5)4] in C6D5Cl affords [(C5R5)2ZrR'(ClC6D5)][B(C6F5)4] chlorobenzene complexes (1-d5, R' = CH2Ph and (C5R5)2 = (C5H5)2; 2a-d-d5, R' = Me and (C5R5)2 = rac-(1,2-ethylene(bis)indenyl) (2a), (C5H5)2 (2b), (C5H4Me)2 (2c), (C5Me5)2 (2d, C5Me5 = Cp*)). Complexes 1 and 2b,c are thermally robust but are converted to [{(C5R5)2Zr(mu-Cl)}2][B(C6F5)4]2 (4b,c) by a photochemical process in ClPh solution. In contrast, 2d undergoes facile thermal ortho-C-H activation to yield [Cp*2Zr(eta2-C,Cl-2-Cl-C6H4)][B(C6F5)4] (5), which slowly rearranges to [(eta4,eta1-C5Me5C6H4)Cp*ZrCl][B(C6F5)4] (6) via beta-Cl elimination and benzyne insertion into a Zr-CCp* bond. The higher thermal reactivity of 2d versus that of 1 and 2b,c is attributed to steric crowding associated with the Cp* ligands of 2d, which forces a ClPh ortho-hydrogen close to the Zr-Me group.
Wu
Fan
F
Department of Chemistry, The University of Chicago, 5735 South Ellis Avenue, Chicago, IL 60637, USA.
Dash
Aswini K
AK
Jordan
Richard F
RF