Terphenyl Substituents Research Articles

Synthesis and Characterization of Sterically Encumbered Derivatives of Aluminum Hydrides and Halides: Assessment of Steric Properties of Bulky Terphenyl Ligands.

The synthesis and characterization of several sterically encumbered monoterphenyl derivatives of aluminum halides and aluminum hydrides are described. These compounds are [2,6-Mes(2)C(6)H(3)AlH(3)LiOEt(2)](n)() (1), (Mes = 2,4,6-Me(3)C(6)H(2)-), 2,6-Mes(2)C(6)H(3)AlH(2)OEt(2) (2), [2,6-Mes(2)C(6)H(3)AlH(2)](2) (3), 2,6-Mes(2)C(6)H(3)AlCl(2)OEt(2) (4), [2,6-Mes(2)C(6)H(3)AlCl(3)LiOEt(2)](n)() (5), [2,6-Mes(2)C(6)H(3)AlCl(2)](2) (6), TriphAlBr(2)OEt(2) (7), (Triph = 2,4,6-Ph(3)C(6)H(2)-), [2,6-Trip(2)C(6)H(3)AlH(3)LiOEt(2)](2) (8) (Trip = 2,4,6-i-Pr(3)C(6)H(2)-), 2,6-Trip(2)C(6)H(3)AlH(2)OEt(2) (9), [2,6-Trip(2)C(6)H(3)AlH(2)](2) (10), 2,6-Trip(2)C(6)H(3)AlCl(2)OEt(2) (11), and the partially hydrolyzed derivative [2,6-Trip(2)C(6)H(3)Al(Cl)(0.68)(H)(0.32)(&mgr;-OH)](2).2C(6)H(6) (12). The structures of 2, 3a, 4, 6, 7, 9a, 10a, 10b, 11, and 12 were determined by X-ray crystallography. The structures of 3a, 9a, 10a, and 10b, are related to 3, 9, and 10, respectively, by partial occupation of chloride or hydride by hydroxide. The compounds were also characterized by (1)H, (13)C, (7)Li, and (27)Al NMR and IR spectroscopy. The major conclusions from the experimental data are that a single ortho terphenyl substituent of the kind reported here are not as effective as the ligand Mes (Mes = 2,4,6-t-Bu(3)C(6)H(2)-) in preventing further coordination and/or aggregation involving the aluminum centers. In effect, one terphenyl ligand is not as successful as a Mes substituent in masking the metal through agostic and/or steric effects.

Donor-Free Alkali Metal Thiolates: Synthesis and Structure of Dimeric, Trimeric, and Tetrameric Complexes with Sterically Encumbered Terphenyl Substituents.

The synthesis and characterization of the tetrameric lithium thiolate (LiSC(6)H(2)-2,4,6-Ph(3))(4).C(7)H(8) (1), the trimeric lithium thiolate (LiSC(6)H(3)-2,6-Mes(2))(3).C(6)H(14)()()(2) (Mes = 2,4,6-Me(3)C(6)H(2)), the thiol HSC(6)H(3)-2,6-Trip(2) (3) (Trip = 2,4,6-i-Pr(3)C(6)H(2)), and the complete alkali metal series of dimeric thiolates (MSC(6)H(3)-2,6-Trip(2))(2) (M = Li (4, 5), Na (6), K (7), Rb (8), Cs (9)) are described. The compounds were characterized by (1)H, (7)Li, and (13)C NMR and IR spectroscopy and by X-ray crystallography. The compounds 1 and 2 crystallize as four- and three-rung ladder framework structures. The compounds 4-9 crystallize as dimers with M(2)S(2) cores. In addition, the metal ions interact with the ortho aryl groups to varying degrees in all the structures. The extent of these interactions appears to be determined mainly by ionic sizes and geometric factors. The coordination geometry of the thiolato sulfurs also varies from pyramidal in 1, 2, 4, 5, and 6 and one planar and one slightly pyramidal sulfur geometry in 7 to both sulfurs being planar coordinated in 8 and 9. Crystal data at 130 K are as follows: (LiSC(6)H(2)-2,4,6-Ph(3))(4).C(7)H(8) (1), a = 15.961(2) Å, b = 16.243(3) Å, c = 17.114(3) Å, alpha = 89.375(14) degrees, beta = 85.334(14) degrees, gamma = 63.343(12) degrees, V = 3950(1) Å(3), space group P&onemacr;, Z = 2, R(1) = 0.082; (LiSC(6)H(3)-2,6-Mes(2))(3).C(6)H(14)()()(2), a = 14.554(4) Å, b = 14.010(4) Å, c = 32.832(8) Å, beta = 95.20(2) degrees, V = 6667(2) Å(3), space group P2(1)/n, Z = 4, R(1) = 0.089; HSC(6)H(3)-2,6-Trip(2) (3), a = 8.180(2) Å, b = 25.437(5) Å, c = 15.752(3) Å, V = 3278(1) Å(3), space group Pnma, Z = 4, R(1) = 0.045; (LiC(6)H(3)-2,6-Trip(2))(2) (4), a = 12.652(2) Å, b = 14.218(1) Å, c = 18.713(2) Å, alpha = 83.56(1) degrees, beta = 84.36(1) degrees, gamma = 73.82(1) degrees, V = 3205(1) Å(3), space group P&onemacr;, Z = 2, R(1) = 0.055; (LiC(6)H(3)-2,6-Trip(2))(2).C(7)H(8) (5), a = 15.383(3) Å, b = 14.381(2) Å, c = 16.524(2) Å, beta = 111.10(1), V = 3410.3(9) Å(3), space group P2(1)/n, Z = 2, R(1) = 0.086; (NaSC(6)H(3)-2,6-Trip(2))(2).0.5C(7)H(8) (6), a = 13.952(2) Å, b = 20.267(2) Å, c = 24.475(3) Å, beta = 98.673(9) degrees, V = 6842(1) Å(3), space group P2(1)/n, Z = 4, R(1) = 0.068; (KSC(6)H(3)-2,6-Trip(2))(2).C(7)H(8) (7), a = 13.683(4) Å, b = 15.071(4) Å, c = 17.824(5) Å, alpha = 82.73(2), beta = 86.09(2), gamma = 88.46(2), V = 3637(2) Å(3), space group P&onemacr;, Z = 2, R(1) = 0.072; (RbSC(6)H(3)-2,6-Trip(2))(2).C(7)H(8) (8), a = 19.710(3) Å, b = 20.892(3) Å, c = 18.755(2) Å, beta = 106.900(9) degrees, V = 7389(2) Å(3), space group P2(1)/n, Z = 4, R(1) = 0.069; (CsSC(6)H(3)-2,6-Trip(2))(2) (9), a = 13.109(3) Å, b = 15.941(3) Å, c = 17.748(4) Å, alpha = 101.65(2) degrees, beta = 100.76(2) degrees, gamma = 104.25(2) degrees, V = 3410(1) Å(3), space group P&onemacr;, Z = 2, R(1) = 0.048.