Synthesis and Structural Systematics of Nitrogen Base Adducts of Group 2 Salts. VIII. Some Mixed-Ligand Complexes of Group 2 Metal Halides With Aromatic N,N'-Bidentate and Oxygen Donors

Abstract

Room-temperature single-crystal X-ray structural characterizations have defined an interesting array of species obtained by variously crystallizing Group 2 halides with 2,2'-bipyridine ( bpy ) and 1,10-phenanthroline ( phen ) from hydroxylic solvents. [( phen )₂Ca(OH₂)₃]Br₂ (1) is monoclinic, P2₁/c, a 16.896(5), b 8.620(2), c 17.814(5) Ǻ, β 97.05(2)°, Z = 4 f.u .; conventional R on ׀ F ׀ was 0.057 for 1707   independent 'observed' (I > 3σ(I)) reflections N_o, the complex   containing seven-coordinate Ca(N₂)₂O₃ calcium. [( bpy )₂CaBr(OH₂)( HOPri )]   Br (2) is monoclinic, P2₁/c, a 9.674(4), b 18.236(8), c 14.716(8) Ǻ, β 90.83(4)°, Z = 4 f.u ., R 0.044 for N_o 2349, with seven-coordinate [CaBr (N₂)₂O₂] calcium. [( bpy )₂CaBr₂( HOPr )] (3), [( bpy )₂CaBr₂( HOBu )] (4) and [( bpy )₂SrBr₂( HOPr )] (5) are all isomorphous, triclinic, Pī, a ≈ 17,   b ≈ 9.6, c ≈ 7.7 Ǻ, α ≈ 105, β ≈ 94, γ ≈ 95°, Z = 2 f.u .; R 0.055, 0.037, 0.061 for No 3111, 3102, 2424 respectively; all have a seven-coordinate [MX₂(N₂)₂O] metal environment. A similar array is found in [(phen)₂CaBr(OH₂)( HOMe )] Br (6), triclinic, Pī , a 16.761(8), b  10.647(6), c 7.376(6) Ǻ, α 75.78(6), β 82.47(5), γ 75.86(5)°, Z = 2 f.u ., R 0.057 for N_o 3216. With bpy , from aqueous methanol, however, [(bpy)₂Ca(OH₂)₂( HOMe )₂] Br₂ (7) was obtained, monoclinic, C2/c, a   17.645(7), b 10.899(4), c 16.071(5) Ǻ, β 118.88(2)°, Z = 4 f.u ., R 0.044 for No 1448, containing eight-coordinate Ca(N₂)₂O₄ calcium; the calcium is disposed on a twofold axis. [( bpy )₂SrBr₂( HOMe )₂] (8) is triclinic, Pī , a 13.784(5), b 10.605(4), c 9.653(1) Ǻ, α 115.78(2), β 96.87(3), γ 96.67(3)°, Z = 2 f.u ., R 0.045 for No 2754; the  strontium is eight-coordinate [SrBr₂(N₂)₂O₂]. [( phen )₂Sr(OH₂)₄] I₂.2phen (9), triclinic, Pī , a 13.314(4), b 12.311(3), c 7.066(2) Ǻ, α 99.77(2), β 92.43(2), γ 77.27(2)°, Z = 1 f.u ., R 0.049 for N_o 2703, is isomorphous with the previously studied perchlorate analogue, the strontium being disposed on a centre of symmetry. Species (1)-(9) are all mononuclear; the barium adducts (10) and (11) are binuclear: [( phen )₂Ba(OH₂)₂Cl(μ-OH₂)₂Cl(H₂O)₂Ba( phen )₂] Cl₂.2phen.4H₂O (10) is triclinic, Pī , a 14.590(3), b 14.109(4), c 10-862(2) Ǻ, α 74.56(2), β 65.87(2)°, γ 63.59(2)°, Z = 1 centrosymmetric dimer, R 0.027 for No 5249, with nine-coordinate Ba (N₂)2ClO₂(μ-O)₂ barium. [( bpy )₂Ba(I/OH₂)(μ- I)₃(I/OH₂) Ba ( bpy )₂] (11) is monoclinic, P 2/c, a 13.988(2), b 11.00(2), c 20.900(7) Ǻ, β 127.59(2)°, Z = 2 dimers , R 0.069 for No 3353, with eight-coordinate Ba (N₂)₂(I/OH)(μ-I)₃ barium. All of (1)-(11) contain M(N₂)₂ arrays with diverse associations of solvent oxygen atoms, and in some cases halogens. Species (12), [( bpy )BaBr₂( HOMe )2] (∞ ׀ ∞), is polymeric, monoclinic, C 2/c, a 17.119(2), b 13.844(1), c 7.489(1) Ǻ, β 111.21(1)°, Z = 4 f.u ., R 0.057 for N_o 2326; the barium lies on a twofold axis in an eight-coordinate [ Ba (N₂)(O)₂(μ-Br)4] environment. An adduct (13) of barium iodide with 4,4'-bipyridine, BaI₂/(4,4'-bpy)/ PrOH (1:2½:2), monoclinic, P 2₁/c, a l5.467(5), b 12.639(7), c 21.004(5) Ǻ, β 118.99(3)°, Z = 4, R 0.059 for No 2.003, is a one-dimensional polymer, linked by two of the 4,4'-bpy ligands , one of these being centrosymmetric; the third ligand occupies a lattice site, so that the complex is [(4,4′-bpy)(4,4′-bpy)_½Ba( HOPr )₂](∞ ׀ ∞).(4,4'-bpy). The barium environment is seven-coordinate pentagonal bipyramidal, the two iodines occupying the axial/trans sites and the two oxygens non-adjacent in the pentagonal plane.