
TY  - JOUR
A1  - Waters, AF 
A1  - White, AH 
T1  - Synthesis and Structural Systematics of Nitrogen Base Adducts of Group 2 Salts. II. Some Adducts of Group 2 Salts With Pyridine
JF  - Australian Journal of Chemistry
JO  - Aust. J. Chem.
Y1  - 1996
VL  - 49
IS  - 1
SP  - 35
EP  - 46
KW  - 
UR  - https://doi.org/10.1071/CH9960035 
N2  - Recrystallization of Group 2 halides from pyridine ( py ) solution has yielded, in a number of cases, crystalline adducts MX2.npy which have been the subject of room-temperature single-crystal X-ray structural characterization. MgBr2.6py (1) is orthorhombic, Ccca, a 11.575(2), b 14.999(4), c 17.292(2) &#506;, Z = 4; conventional R on [F] for No = 752 'observed' (I > 3&#963;(I)) reflections was 0.043. The compound is formulated as [( py )4MgBr2].2py, the metal atom on a site of 222 symmetry having a trans-X2MN4 coordination environment. With CaCl2, a 1:2 adduct (2) is formed, orthorhombic, Fdd2, a 33.83(1), b 18.143(2), c 3.981(7) &#506;, Z = 8 f.u ., R 0.040 for No 451; the complex is an infinite polymer along c, [( py )2CaCl2](&#8734; &#1472; &#8734;), the&#8230;CaCl2CaCl2Ca&#8230;spine having six-coordinate, octahedral calcium environments in which the pyridine nitrogen atoms are bound trans to either side, with the calcium site symmetry being 2. With SrBr2, a 1:5 adduct (3) is found, mononuclear, [( py )5SrBr2], with the metal atom in a pentagonal bipyramidal coordination environment (orthorhombic, Pcab , a 18.611(5), b 17.768(7), c 17.411(7) &#506;, Z = 8; R 0.060 for No 949). With BaI2, a 1:6 adduct (4) is obtained, [( py )6BaI2], the eight-coordinate barium atom lying on a crystallographic 2 axis in a monoclinic C2/c cell, Z = 4, a 18.311(2), b 9.960(3), c l8.856(8) &#506;, &#946; 99.28(3)&#176; (R 0.031 for No 2279), with the iodide atoms occupying a pair of B sites in one of the trapezoidal planes of a quasi-dodecahedral array. [(2-mpy)2MgBr2] (5), 2-mpy=2-methylpyridine, is of interest, offering a four-coordinate N2MgBr2 array (triclinic, P&#299;, a 8.046(3), b 8.873(3), c 11.475(1) &#506;, &#945; 86.25(2), &#946; 78.82(5), &#947; 67.88(5)&#176;, Z = 2; R 0.069 for No 2091), while [( py )6/(4-mpy)6Ba(O2ClO2)2] (6) and (7), perhaps surprisingly, are isomorphous with (4), with O,O'-bidentate perchlorates replacing iodide in the coordination sphere (R 0.031 and 0.052 for No 2401 and 2204 respectively). With 3,5-dmpy (3,5-dimethylpyridine), strontium iodide yields a trans-six- rather than seven-coordinate adduct, [(3,5-dmpy)4SrI2] (8), the molecule conforming to crystallographic 4/m symmetry in the tetragonal space group I4/m, a 9.808(4), c 17.196(8) &#506;, Z = 2; R 0.066 for No 608. 
ER  -

