Synthesis and Structural Systematics of Nitrogen Base Adducts of Group 2 Salts. III. Some Mixed-Ligand Complexes With Pyridine Base and Oxygen Donors

Abstract

In association with the report of a number of homoleptic pyridine base adducts of Group 2 salts in the preceding paper, a number of mixed-ligand compounds have been synthesized and characterized by room-temperature single-crystal X-ray studies. MgI₂.2H₂O.6py ≡ [trans-( py )₄Mg(OH₂)₂]I₂.2py (1) is monoclinic, P2₁/c, a 10.47(1), b 10.0400(8), c 32.77(1) Ǻ, β 92.34(6)°, Z = 4; R was 0.053 for N_o = 2990 independent, observed (I > 3σ(I)) diffractometer reflections. Mg-O are 2.063(8) and 2.061(8), Mg-N ranging between 2.19(1) and 2.23(1) Ǻ. MgI₂.4H₂O.8(3,5-dmpy)≡[trans-(3,5-dmpy)₂Mg(OH₂)₄]I₂.6(3,5-dmpy) (2) is orthorhombic, Pcab , a 22.203(6), b 17.023(8), c 16.548(7) Ǻ, Z = 4 f.u .; R 0.045 for N _o 2457. Mg-O are 2.026(5) and 2.082(5), and Mg-N 2.267(6) Ǻ in the centrosymmetric cation, with which the aggregate of anions and solvent form a discrete hydrogen-bonded cluster. CaBr₂.2H₂O.4(2-mpy) ≡ [trans-CaBr₂(OH₂).2(2-mpy)2].2(2-mpy) (3) is monoclinic, P 2₁/c, a 7.076(1), b 9.329(3), c 21.957(2) Ǻ, β 98.34(1)°, Z = 2 f.u .; R 0.076 for N_o 1599; Ca-Br, N, O are 2.840(1), 2.56(1), 2.355(6) Ǻ respectively; its 3-mpy counterpart (4) has a very similar cell but with b and c transposed; R was 0.047 for N_o 2116, and Ca-Br, N, O 2.8902(6), 2.500(5), 2.344(3) Ǻ. Sr (ClO4)2.3py.dmf ≡ [ Sr (O2ClO2)2( py )3(O- dmf )] (5) is monoclinic, P2₁, a 8.814(2), b 16.985(7), c 9.499(1) Ǻ, β 114.97(1)°, Z = 2; R 0.047 for N_o 1717. The strontium is eight-coordinate: Sr -O(ClO₄) are 2.644(8)-2.69(1), Sr-N 2.64(1)-2.69(1), Sr -O( dmf ) 2.417(9) Ǻ. The other two compounds, Ba (ClO₄)₂.H₂O.L (L = py (6), 3-mpy (7)), are two-dimensional polymers, linked by bridging perchlorate ions and water molecules. Compound (6) is orthorhombic, Pnna , a 24.098(3), b 10.444(1), c 4.871(3) Ǻ, Z = 4 f.u ., R 0.025 for N _o 688: the barium is 11-coordinate Ba (O(H2O))2(O(ClO4))8N with m symmetry, Ba -N 2.889(7), Ba-O(H₂O)₂.943(4), Ba-O(ClO₄) 2.844(6)-2.942(5) Ǻ. Compound (7) is monoclinic, P 2₁/c, a 7.421(4), b 24.479(8), c 7.293(7) Ǻ, β 104.80(6)°, Z = 4 f.u ., R 0.041 for N _o 2033; the barium is nine-coordinate Ba (O(H₂O))₂(O(ClO₄))₆N, Ba-N 2.839(7), Ba -O(H₂O) 2.791(5), 3.049(5), Ba-O(ClO₄) 2.753(6)-2.936(6) Ǻ.