Mono(pentamethylcyclopentadienyl)titanium and -zirconium complexes supported by chiral diolate ligands. X-ray crystal structures of [(eta-C5Me5)TiCl(mu-eta(1),eta(1)-2-CF3-dpbd)](2) and [HNEt3][(eta-C5Me5)(2)Zr2Cl2(mu-Cl)(mu-eta(1),eta(2)-3,5-Me-2-dp

摘要

Reaction of optically pure (S,S)-butadiene diepoxide (1) with 2 equiv of Grignard reagent ArMgBr (Ar = 2-CF3C6H4 or 3,5-Me2C6H3) in the presence of copper(I) iodide produces the chiral substituted diphenylbutanediols (dpbd) (2S,3S)-ArCH2CH(OH)CH(OH)CH2Ar (Ar = 2-CF3C6H4 (2), abbreviated 2-CF3-dpbdH(2); Ar = 3,5-Me2C6H3 (3), abbreviated 3,5-Me-2-dpbdH(2)). The mono(pentamethylcyclopentadienyl) halide complex (eta-C5Me5)TiCl3 reacts with 1 equiv of diol 2 in the presence of triethylamine to produce the dimeric species [(eta-C5Me5)TiCl(mu-eta(1),eta(1)- 2-CF3-dpbd)](2) (4). An analogous reaction employing the zirconium halide (eta-C5Me5)ZrCl3 and the diol 3 leads to isolation of the salt complex [HNEt3] [(eta-C5Me5)(2)Zr2Cl2(mu-Cl)(mu-eta(1),eta(2)-3,5-Me-2-dpbd)(2)] (5). Compounds 4 and 5 have been subjected to single-crystal X-ray diffraction studies. The solid-state structure of 4 consists of two titanium metal centers, each bearing a pentamethylcyclopentadienyl ligand and a terminal chloride Ligand, bridged by two diolate ligands such that a central 10-membered ring is formed. The terminal Ti-CI bond length is 2.306(2) Angstrom, and the Ti-O distances range from 1.783(4) to 1.830(5) Angstrom. The two bridging diolate ligands adopt widely differing conformations such that one diolate ligand possesses Ti-O-C angles of 172.3(4) and 172.4(4)degrees while the other displays acute Ti-O-C angles of 125.2(4)degrees. The molecular geometry of the anion in 5 is comprised of two (eta-C5Me5)ZrCl moieties bridged by a single mu(2)-Cl ligand and two diolate ligands. One oxygen atom within each diolate ligand acts as a mu(2) bridge between the zirconium metal centers whereas the other is bound in a terminal fashion to one metal center, thus forming a central Zr2O2 four-membered ring and two ZrO2C2 five-membered rings. Bridging Zr-Cl distances are 2.606(4) and 2.737(3) Angstrom, and terminal Zr-Cl bond lengths are 2.499(4) and 2.584(4) Angstrom. Terminal Zr-O distances are 1.989(9) and 1.972(9) Angstrom, and bridging Zr-O distances range from 2.125(9) to 2.222(8) Angstrom. Crystal data for 4 (at -90 degrees C): monoclinic space group P2(1), a = 12.399(1), b = 22.229(2), c = 13.275(1) Angstrom, beta = 111.208(6)degrees, V = 3411 Angstrom(3), Z = 2, D-calc = 1.338 g cm(-3). Crystal data for 5 (at -90 degrees C): orthorhombic space group P2(1)2(1)2(1), a = 13.615(2), b = 13.623(2), c = 36.042(5) Angstrom, V = 6685 Angstrom(3), Z = 3, D-calc = 1.246 g cm(-3). [References: 76]