1-Methylimidazolin-2-yl functionalized cyclopentadienyl complexes of titanium and zirconium.: Crystal structure of {[η5:η1-κN-C5H4CPh2CH2-(1-Me-C3H4N2)]ZrCl2}2(μ-Cl)2

The novel bidentate ligand, C(5)H(4)CPh(2)CH(2)-(1-Me-C(3)H(4)N(2)) ( 3), has been prepared and characterized as its lithium salt LiC(5)H(4)CPh(2)CH(2)-(1-Me-C(3)H(4)N(2)) (3-Li). Cyclopentadiene HC(5)H(4)CPh(2)CH(2)-(1-Me-C(3)H(4)N(2)) (3-H) has been obtained from 6,6-diphenylfulvene and 1,2-dimethylimidazoline ( 1). In THF-d8 solution in the presence of 1, ( 1-methylimidazoline-2-yl) methyllithium ( 2) has been proved to undergo gradual conversion into a dilithium derivative of N(1)-methyl-N(2)-[( 1E, 2E)-1-methyl-2-(1-methylimidazolidine-2-idene) ethylidene] ethane-1,2-diamine ( 2a). In a solution, cyclopentadiene 3-H has been shown to undergo isomerization into 3-{N-[2-(N-methylamino)ethyl] amino}-1,1-diphenyl-1,2-dihydropentalene (4) and, further, into a mixture of 4 and two rotameric 3-[N-(2-aminoethyl)-N-methylamino]-1,1-diphenyl-1,2- dihydropentalenes ( 5a) and ( 5b). Treatment of the lithium salt 3-Li with Me(3)SiCl has lead to 3-{ N-[ 2-(N-trimethylsilylamino)ethyl]amino}-1,1-diphenyl-1,2-dihydropentalene ( 6) as the dominant component in the reaction mixture. In the latter case the expected Me(3)Si-C(5)H(4)CPh(2)CH(2)-(1-Me-C(3)H(4)N(2)) (3-Si) was not observed. Stannylation of 3-Li with 1 equiv. of Me(3)SnCl has resulted in formation of a mixture of Me(3)Sn-C(5)H(4)CPh(2)CH(2)-(1-Me-C(3)H(4)N(2)) (3-Sn), (Me(3)Sn)(2)-C(5)H(3)CPh(2)CH(2)-(1-Me-C(3)H(4)N(2)) ( 3-Sn(2)), and cyclopentadiene 3-H in a ca. 2:1:1 molar ratio. Monocyclopentadienyl complexes {[eta(5):eta(1)-kappa N-C(5)H(4)CPh(2)CH(2)( 1-Me-C(3)H(4)N(2))] MCl(3) ( M = Ti ( 7), Zr ( 8)) have been prepared starting from the organotin and organolithium compounds 3-Sn and 3-Li, respectively. The dynamic behavior of complexes 7 and 8 has been investigated by means of variable-temperature NMR spectroscopy in solutions. The molecular structures of the dihydropentalene 4, binuclear complex {[eta(5):eta(1)-kappa N-C(5)H(4)CPh(2)CH(2)-(1-Me-C(3)H(4)N(2))]-ZrCl(2)} 2(mu-Cl)(2) 8, and a coordination dimer of the dilithium salt 2a have been established by X-ray diffraction analysis. In the crystal structure of the 2a-dimer, the shortest known Li-Li contact has been found. (C) 2008 Elsevier B. V. All rights reserved.