Covalent titanium aryldioxy one-, two-, and three-dimensional networks and their examination as Ziegler-Natta catalysts.
Treatment of ((i)PrO)4Ti with 2,7-dihydroxynaphthalene at 100 degrees C afforded the one-dimensional ladder [cis-Ti(mu(2,7)-OC10H6O)2py2]n (1: C30H22N2O4Ti, orthorhombic, P2(1)2(1)2(1), a = 9.866(2) A, b = 15.962(3) A, c = 16.223(3) A, Z = 4), in pyridine, and the stacked ladder, two-dimensional [Ti(mu(2,7)-OC10H6O)2(4-picoline)2.(4-picoline)(0.5)]n (2: C70H59N5O8Ti2, triclinic, P1, a = 10.814(2) A, b = 16.785(3) A, c = 18.020(4) A, alpha = 93.88(3) degrees, beta = 107.31(3) degrees, gamma = 108.77(3) degrees, Z = 2), in 4-picoline. A disruption of intramolecular edge-to-face and intermolecular face-to-face pi-stacking interactions in 1 by the Me group of the 4-picoline causes the structural change to 2. These derivatives and related two- and three-dimensional covalent metal organic networks (CMON) were assayed for ethylene and propylene polymerization activity via the addition of methylaluminoxane. CMON are mediocre Ziegler-Natta catalysts that generate polydisperse, linear polyethylene and atactic polypropylene. The data are best accommodated by viewing the degradation of CMON into numerous active sites of differing activity.
Tanski
J M
JM
Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853, USA.
Wolczanski
P T
PT