Organoamido- and Aryloxo-Lanthanoids. XI. Syntheses and Crystal Structures of Nd(Odpp)₃, Nd(Odpp)₃(thf) and [Nd(Odpp)₃(thf)₂].2(thf) (Odpp^-=2,6-Diphenylphenolate): Variations in Intramolecular π-Ph-Nd Interactions

Abstract

The X-ray crystal structure of Nd (Odpp)₃ ( Odpp^- = 2,6-diphenylphenolate), obtained by sublimation of Nd ( Odpp )₃( thf )₂ ( thf = tetrahydrofuran ) [triclinic, Pī , a 15.835(5), b 13.499(10), c 10.955(11) Ǻ, α 116.25(7), β 92.87(7), γ 101.66(6)°, V 2031 Ǻ³, Z2, N_o 5726 'observed' data (I > 3σ(I)) refined to conventional R 0.047 shows a near triangular array of oxygens surrounding neodymium { Nd -O} 2.16₉ Ǻ, ∑ O- Nd -O 353.₂° with additional, intramolecular Nd-η⁶-Ph chelate interactions { Nd -C} 3.04₆ Ǻ and Nd-η¹-Ph ( Nd -C 2.964(7)Ǻ). There is a pseudotrigonal bipyramidal arrangement of the oxygens, the centroid of the η⁶-Ph, and the η¹-carbon. The complex Nd ( Odpp )₃( thf ), obtained by crystallization of Nd ( Odpp )₃( thf )₂ from toluene (monoclinic, P2₁/c, a 12.213(4), b 21.447(4), c 17.744Ǻ, β 104.25(2)°, V 4505 Ǻ³, Z 4, R 0.042 for N_o 8014) also has pseudotrigonal bipyramidal stereochemistry, with a triangular equatorial array of aryl oxide oxygens { Nd -O} 2.19₃ Ǻ; ∑ O- Nd -O 358.₇°, an apical thf oxygen (Nd -O 2.446(3)Ǻ), and an apical intramolecular chelating phenyl group. As the last has three Nd -C contacts (3.094(5), 3.144(5), 3.010(5)Ǻ) significantly shorter than the other three (3.300(5), 3.427(5), 3.377(5)Ǻ), an η³-Ph-Nd interaction seems likely. For [ Nd ( Odpp )₃( thf )₂].2( thf ), obtained by crystallization from tetrahydrofuran without drying of the crystals, the X-ray structure (monoclinic, P2₁, a 10.230(2), b 21.919(5), c 13.411(4) Ǻ, β 101.15(2)°, V 2950 A3, Z2, R 0.058 for N_o 3237) reveals a distorted trigonal bipyramidal arrangement of three aryl oxide oxygens (two equatorial 2.208(9), 2.16(1) Ǻ; one axial 2.203(9) Ǻ) and two thf oxygens (one equatorial 2.44(1) Ǻ; one axial (significantly distant) 2.62(1) Ǻ). The X-ray structure of [La( Odpp )₃( thf )₂].2( thf ) shows it to be isostructural with the neodymium analogue.