Syntheses of [ethylene-1,2-bis(.eta.5-4,5,6,7-tetrahydro-1-indenyl)]zirconium and -hafnium hydride complexes. Improved syntheses of the corresponding dichlorides

Treatment of (EBTHI)MCl 2 [M=Zr, 1; M=Hf, 2; EBTHI=ethylene-1,2-bis(η 5 -4,5,6,7-tetrahydro-1-indenyl)] with 2 equiv of NaEt 3 BH in C 6 H 6 produces the hydride dimers [(EBTHI)MH(μ-H)] 2 (M=Zr, 3; M=Hf, 4). The dimethylhafnium complex (EBTHI)HfMe 2 (5) is formed when 2 is treated with MeLi in C 6 H 6 . Complexes 3 and 4 can be protonated with the weak acid [PhMe 2 NH][Co(C 2 B 9 H 11 ) 2 ] to give monomeric cationic hybrides [(EBTHI)M(H)(NPhMe 2 )][Co(C 2 B 9 H 11 ) 2 ] (M=Zr, 6; M=Hf, 7), in which the N,N-dimethylaniline ligand is very weakly coordinated to the metal