REACTION OF (CP(2)ASTERISK-LNH)(2) (LN=Y, LA) AND CP(2)ASTERISK-Y(2-C(6)H(4)CH(2)NME(2)) WITH ESTERS AND AMIDES AND MOLECULAR-STRUCTURE OF [CP(2)ASTERISK-Y(MU-OCME=CHC(OET)O)](2)

The activation of esters and amides by (Cp(2)*LnH)(2) [Ln = Y (1a), Ln = La (1b), Cp*=C(5)Me] and Cp(2)*Y(2-C(6)H(4)CH(2)NMe(2)) (2) is described. Compounds 1a and 1b react with ethyl acetate to form Cp(2)*YOEt (3a) and Cp(2)*LaOEt (30). With 1a and ethyl benzoate a 1:1 mixture of 3a and Cp(2)*YOCH(2)Ph (4a) is produced and the corresponding 1:1 mixture of 3b and Cp(2)*LaOCH(2)Ph (4b) is observed with 1b. Ethyl acrylate is polymerized rapidly by both 1a and 1b. The reaction of 1a with N,N-dimethyl-acetamide leads to a mixture of the carbonyl insertion product Cp(2)*Y(OCH(NMe(2))Me) (5) and the aldol condensation product Cp(2)*Y(OC(NMe(2)) (Me)CH2C(O)NMe(2)) (6). Formation of the condensation product [Cp(2)*Y(mu-OCMe=CHC(OEt)O)](2) (7) occurred when 2 was reacted with ethyl acetate. The molecular structure of 7 was determined by X-ray diffraction: a = 10.129(1) Angstrom, b = 10.650(1) Angstrom, c = 12.093(1) Angstrom, alpha = 77.642(6)degrees, beta = 79.402(7), gamma = 86.408(9), V = 1252.2(2) Angstrom(3), space group <P(1)over bar>, Z = 1. Anisotropic least-squares refinement based on 4871 reflections converged to R(F) = 0.034 and R(W) = 0.041 for 428 refined parameters. The more sterically hindered ester ethyl 2-methylpropanoate reacted with 2 to produce the enolate complex Cp(2)*Y{OC(2-C(6)H(4)CH(2)NMe(2))=CMe(2)} (Me(2)CHCOOEt) (8). With N,N-dimethyl-acetamide 2 gives a dean aldol condensation to form 6.