1-Methylimidazolin-2-yl functionalized cyclopentadienyl complexes of titanium and zirconium. Crystal structure of {[η⁵:η¹-κN-C5H 4CPh2CH2-(1-Me-C3H4 N2)]ZrCl2}2(μ-Cl)2

Abstract 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- d 8 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 -[(1 E ,2 E )-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 {[η 5 :η 1 -κ 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 {[η 5 :η 1 -κ N -C 5 H 4 CPh 2 CH 2 -(1-Me–C 3 H 4 N 2 )]ZrCl 2 } 2 (μ-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.