Guido Seifert

The chemistry of 1,3,5-triazacyclohexane complexes 5: cationic zinc(II) alkyl complexes of N-alkylated 1,3,5-triazacyclohexanes and 13-benzyl-1,5,9-triazatricyclo[7.3.1.05,13]-tridecane

Abstract Diethylzinc reacts with hydroperchlorates of N-alkylated 1,3,5-triazacyclohexanes (R 3 TAC; R = methyl (Me), benzyl (Bz), isopropyl ( i Pr)) and with the hydrotetrafluoroborate of 1,3,5-tris-( para -fluorobenzyl)-1,3,5-triazacyclohexane (FBz 3 TAC) to give the corresponding cationic zinc ethyl complexes [(R 3 TAC)Zn(Et)][X] (X = ClO 4 − , BF 4 − ). Similar complexes were obtained from diethylzinc treated with [HNMe 2 Ph][BF 4 ] or [HNMe 2 Ph][B(C 6 F 5 ) 4 ](Et 2 O) in the presence of R 3 TAC (R = Bz, FBz, s-1-phenylethyl (s-PhMeCH)). A product of decomposition of [(Bz 3 TAC)Zn(Et)][ClO 4 ] was analyzed by X-ray diffraction. The structures of [({s-PhMeCH} 3 TAC)Zn(Et)][BF 4 ] an [(FBz 3 TAC)Zn(Et)][BF 4 ] were estimated using nuclear Overhauser enhancement spectroscopy. Protonolysis of diethylzinc with [HNMe 2 Ph][BF 4 ] in the presence of 13-benzyl-1,5,9-triazatricyclo[7.3.1.0 5,13 ]-tridecane (BzTATC) yielded the complex [(BzTATC)Zn(Et)][BF 4 ].

1,3,5-Triazacyclohexane Complexes of Chromium as Homogeneous Model Systems for the Phillips Catalyst

1,3,5-triazacyclohexane complexes 2 prepared from trizazacyclohexanes 1 and CrCl3 can be activated by MAO or AIR3/PhNMe2H(BPhF 4) to give solutions that can polymerise and/or trimerise ethylene depending on the N-substituents R with unprecedented high activities. α-olefins are selectively trimerised or co-polymerised with ethylene. We have varied these substituents R in symmetrical and asymmetrical R2R’-triazacyclohexanes including some with different functional groups for a better understanding of this dependence. A detailed study of the activities and the polymer structures shows that these systems are very good models for the Phillips catalyst. The homogeneous reactions can be studied by several spectroscopic methods especially for the α-olefin trimerisation. The results show that the triazacyclohexane stays co-ordinated during the catalysis and that mono-nuclear metallacyclic complexes are likely involved.