Zirconium meso-Octaethylporphyrinogen as Carrier for Sodium Hydride in Toluene: Zirconium-Sodium Bimetallic Hydride and Alkyls

The reaction of the tetralithium meso-octaethylporphyrinogen Et8N4Li4(THF)4 (2) with ZrCl4(THF)2 led to the formation of [(eta5-eta1-eta5-eta1-Et8N4)Zr(THF)] (3), containing two eta5 and two eta1 pyrrolyl anions bonded to zirconium. Such a complex acts as a bifunctional acid-base system able to dissolve ionic salts in their monomeric or dimeric form in hydrocarbon solution. The reaction of 3 with NaH in toluene led to the complexation of NaH via the interaction of the hydride with the Lewis acid Zr and the eta5 complexation of Na by the pyrrolyl anions in [{eta5-eta1-eta1-eta1-Et8N4)-Zr}2(mu-NaH)2] (4). Complex 4 reacts with terminal olefins in toluene by inserting the C=C double bond in the Zr-H functionality and so forming, in the case of ethylene, [{eta5-eta1-eta1-eta1-Et8N4)Zr(CH2CH3)}2(mu-Na)2] (5) and, in the case of 1-hexene, [{eta5-eta1-eta1-eta1-Et8N4)Zr(CH2(CH2)4CH3)}2(mu-Na)2] (6). Similarly, 4 adds to PhC=CH, which leads to the corresponding vinyl complex [(eta5-eta1-eta1-eta1-Et8N4)Zr-trans-(CH=CHPh)]2 (7). The dimeric structure of 4 remains intact after the reaction giving 5-7, however, in these products, major differences in the Na-porphyrinogen interaction modes can be seen. The reaction of 4 with C2H4 in THF led to a Zr-H porphyrinogen monomeric species identical to that formed from dissolving 5 in THF, [{(eta5-eta1-eta1-eta1-Et8N4)Zr(CH2CH3)}{Na(THF)2}] (8). Crystallographic details: 3 orthorhombic, space group Pbcn, a = 12.935(3) angstrom, b = 12.704(3) angstrom, c = 21.649(3) angstrom, alpha = beta = gamma 90-degrees, Z = 4, R = 0.037; 4 monoclinic, space group C2/c, a = 24.272(3) angstrom, b = 12.640(4) angstrom, c = 21.886(3) angstrom, alpha = gamma = 90-degrees, beta = 101.75(1)degrees, Z = 4, R = 0.053; 5 triclinic, space group P1BAR, a = 11.565(2) angstrom, b = 12.598(2) angstrom, c = 14.327(2) angstrom, alpha = 100.30(1)degrees, beta = 103.65(1)degrees, gamma = 113.73(1)degrees, Z = 1, R = 0.034; 7 monoclinic, space group P2(1)/c, a = 13.815(2) angstrom, b = 24.619(2) angstrom, c = 13.981(2) angstrom, alpha = gamma = 90-degrees, beta = 108.73(1)degrees, Z = 2, R = 0.047; 8 monoclinic, space group P2(1)/c, a = 11.264(1) angstrom, b = 19.646(4) angstrom, c = 20.609(3) angstrom, alpha = gamma = 90-degrees, beta = 101.18(2)degrees, Z = 4, R = 0.042.