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
Authors: Kepert DL , Waters AF , White AH 
Published: November 2018

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 No, 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 No 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 No 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 No 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 No 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.