Synthesis and Structural Systematics of Nitrogen Base Adducts of Group 2 Salts. VII. Some Complexes of Group 2 Metal Halides With Aromatic N,N'-Bidentate Ligands

Abstract

Syntheses and room-temperature single-crystal X-ray structural characterizations are recorded for a number of adducts of Group 2 halides with the aromatic N,N′- bidentate ligands L = 2,2'-bipyridine ( bpy ) and 1,10-phenanthroline ( phen ). One adduct of 1 : 1 MX₂/L stoichiometry is recorded: [( bpy )Ca(μ-Br)_(4/2)](∞ ׀ ∞) (1) is monoclinic, C 2/c, a l7.102(5), b 9.845(1), c 7.600(2) Ǻ, β 107.65(2)°, Z = 4 f.u .; conventional R on #1472; F ׀ at convergence was 0.057 for N_o 817 independent 'observed' ( I > 3σ(I)) reflections, the compound being a one-dimensional polymer… CaL (μ-Br)₂CaL(μ-Br)₂…, with six-coordinate calcium, cis-CaN₂(μ-Br)₄, on a twofold axis. 1 : 2 MX₂/L systems have been described for two types of array: [( bpy )₂CaI₂] (2), orthorhombic, Pnca, a 16.914(4), b 13.80(1), c 9.290(4) Ǻ, Z = 4 f.u .; R 0.039 for N_o 1738, is discrete mononuclear, containing cis-CaN₄I₂ six-coordinate calcium, whereas the barium analogue is an infinite one-dimensional polymer, [( bpy )₂Ba(μ-I)_(4/2)](∞׀ ∞) (3), triclinic, Pī, a 11.318(2), b 11.078(2), c 9.206(4) Ǻ, α 80.87(2), β 77.52(2), γ 87.53(1)°, Z = 2 f.u .; R 0.032 for N_o 4154, with eight-coordinate (N₂)₂Ba(μ-I)₄. The perchlorate analogue, [( bpy )2Ba(μ-OClO₂O)(4/2)](∞ ׀ ∞) (4), although of similar stoichiometry, has a trans-rather than a cis-linked chain; it is monoclinic, P 2₁/c, a 6.606(2), b 18.661(7), c 19.440(8) Ǻ, β 109.45(4)°, Z = 4 f.u .; R 0.044 for No 4060, with μ-I replaced by O,O'-ClO4 bridging units and eight-coordinate barium, (N₂)₂BaO₄. The 1 : 3 MX₂/L system is represented (as its hemi( bipyridine ) 'solvate') by mononuclear [( bpy )₃SrI₂].0.5bpy (5), monoclinic, P 2₁/c, a 20.834(8), b 9.735(4), c 18.460(7) Ǻ, β 114.87(3)°, Z = 4 f.u .; R 0.039 for N_o 3711, containing eight-coordinate strontium, [(N2)3SrI2]; there is also an isomorphous calcium/ perchlorate analogue [( bpy )₃Ca(OClO₃)₂].0.5bpy (6), a 21.413(6), b 9.813(4), c 18.659(2) Ǻ, β 115.67(2)°, R 0.057 for N_o 3090, in which unidentate O-ClO₄ ligands replace the iodine about the metal atom. A 1 : 4 adduct is obtained with CaI₂/phen; ionic [Ca( phen )₄] I₂ (7), triclinic, Pī , a 14.703(3), b 13.292(3), c 11.38(1) Ǻ, α 92.78(4), β 96.15(4), γ 105.22(2)°, Z = 2 f.u ., R 0.053 for No 3658, contains eight-coordinate Ca(N₂)₄ arrays, while the novel 1 : 5 adduct [ Ba ( phen )₄] I₂.MeCN (8) is triclinic, Pī , a 12.170(6), b 13.760(7), c 18 254(8) Ǻ, α 77.05(9), ,β 71.96(4), γ 70.83(9)°, Z = 2 f.u ., R 0.040 for No 4447, containing 10-coordinate barium, [ Ba (N₂)₅]. A 1 : 4 adduct formed with BaBr₂ is [ BrBa( phen )₄] Br.MeOH (9), triclinic, Pī , a 17.748(4), b 17.418(2), c 15.535(7) Ǻ, α 91.63(2), β 100.53(3), γ 115.39(1)°, Z = 4 f.u ., R 0.062 for No 4092, containing nine-coordinate barium, [ BrBa (N₂)₄].