SYNTHESIS OF LANTHANIDE-ALKYLALUMINUM BIMETALLIC COMPLEXES AND STUDIES ON THEIR CATALYTIC ACTIVITIES FOR POLYMERIZATION OF SOME POLAR MONOMERS

Three new lanthanide (Ln)-alkylaluminium (Al) bimetallic complexes wit h the formula [(mu-CF3CO2)(2)Ln(mu-CF3CHO2)AIR(2) . 2THF](2) (Ln = Nd, Y, R=i-C4H9 (i-Bu); Ln=Eu, R=C2H5(Et); THF=tetrahydrofuran) were synt hesized by the reaction of Ln(CF,CO,), (Ln=Nd, Y) with HAI (i-Bu)(2) a nd of Eu(CF3CO2)(3) with AlEt(3), respectively. Their crystal structur es were determined by X-ray diffraction at 233 K. [(mu-CF3CO2)(2)Nd (m u-CF3CHO2)Al(i-Bu)(2) . 2THF](2) (Nd-Al) and [(mu-CF3CO2)(2)Y(mu-CF3CH O2)Al(i-Bu)(2) . 2THF](2) (Y-Al) are isomorphous and crystallize in sp ace group <P(1)over bar> with a=12.441(3) Angstrom [12.347(5) Angstrom for Y-Al], b=12.832(3) Angstrom [12.832(4) Angstrom], c=11.334(3) Ang strom [11.292(8) Angstrom], alpha=104.93 (2)degrees [104.45(4)degrees] , beta=98.47(2)degrees [98.81(4)degrees], gamma=64.60(2)degrees [64.30 (3)degrees], R=0.519 [0.113], R(w)=0.0532 [0.110], Z=1 and [(mu-CF3CO2 )(2)Eu(CF3CHO2)AlEt(2) . 2THF](2)(Eu-Al) in space group P2(1)/n with a =11.913(6) Angstrom, b=14.051(9) Angstrom, c=17.920(9) Angstrom, alpha =101.88(11)degrees, beta=gamma=90 degrees, R=0.0509, R(w)=0.0471 and Z =2. The six CF3CO2- (including CF3CHO2-) of each complex, among which pairs are equivalent, coordinated to Ln and Al in three patterns: (A) the two oxygen atoms in one of the three CF3CO2- type coordinated to t wo different Ln; (B) the two oxygen atoms in the second of CF3CO2- typ e coordinated to Ln and Al, respectively; (C) one of the two oxygen at oms in the third CF3CO2- type bidentately coordinated to two Ln and an other oxygen coordinated to Al and one of the two Ln, respectively. Un like types A and B, in type C the carboxyl carbon with a hydrogen atom bonded to it was found to appear as an sp(3)-hybridized configuration rather than an sp(2)-one. 1D and 2D NMR results further confirmed the existence of such a disproportionated CF3CHO2- ligand. Methyl methacr ylate (MMA) and epichlorohydrin (ECH) could be polymerized by Y-Al or Eu-Al as a single-component catalyst and highly syndiotactic poly(MMA) was obtained. THF could also be polymerized by Y-Al in the presence o f a small amount of ECH.