Syntheses, crystal structures and properties of two cadmium coordination polymers containing bis(2-methylimidazol-1-yl) methane(2-mBIM) and bis(imidazol-1-yl)methane (BIM) ligands

摘要

Coordination polymers, {[Cd(2-mBIM)_3](ClO_4)_2}_n (1) and [Cd(BIM)_2(NO_3)_2]_n (2), have been prepared from the reaction of bis(2-methylimidazol-1-yl)methane(2-mBIM) with Cd(ClO_4)_2 and bis(imidazol-l-yl)methane (BIM) with Cd(NO_3)_2 in ethanol and water, respectively. Their structures were characterized by single crystal X-ray diffraction and IR spectroscopy. Compound 1 crystallizes in the rhombohedral space group R-3c with a = b = 12.3617(5) A, c = 38.896(3)A, gamma = 120 deg, V= 5147.5(5)A~3, z = 6. The Cd~(II) occupies a crystallographic inversion center and is coordinated by six N atoms from six distinct 2-mBIM ligands to form a slightly distorted octahedral geometry. Each 2-mBIM is coordinated to two Cd~(II) cations, linking alternatively four Cd~(II) cations, resulting in a 32-membered M_4L_4 macrometallacycle. Compound 2 crystallizes in the monoclinic space group C2/m with a=14.400(3)A, b = 9.3894(18)A, c = 8.6926(17)A, beta= 123.499(2) deg, V=980.1(3)A~3, z = 2. The Cd coordinates to four nitrogen atoms from four different BIM and two nitrates to form a slightly distorted octahedral geometry. The BIM ligands bridge to form a 1-D infinite double-bridged chain structure with 16-membered M_2L_2 macrometallacyclic structural units.