Copper(II) halide complexes of 2-aminopyrimidines:: Crystal structures of [(2-aminopyrimidine)nCuCl2] (n=1,2) and (2-amino-5-bromopyrimidine)2CuBr2

The reaction Of CuX2 (X = Cl, Br) with 2-aminopyrimidine in aqueous solution, or 2-amino-5-bromopyrimidine in aqueous acid yields compounds of the forms [LCuCl2]. (1), [L(2)CuCl(2)1] (2) and [L'2CuBr2] (3) [L = 2-aminopyrimidine; L'= 2-amino-5-bromo-pyrimidine]. The three compounds all form layered structures in which each copper ion is coordinated to two 2-aminopyrimidine molecules and two halide ions. Common structural threads involve bridging ligation [either by monomeric (1) or hydrogen bonded ligand dimers (2 and 3)], N-(HX)-X-... and N-(HN)-N-... hydrogen bonding and pi-pi stacking interactions as well as semi-coordinate (CuX)-X-... bond formation (1 and 2) or (BrBr)-Br-... interactions (3). Compounds 1 and 2 crystallize as two-dimensional coordination polymers with asymmetrically bihalide bridged (CuX2), chains cross-linked into sheets by the 2-aminopyrimidine molecules (1) or by hydrogen bonded L-2 dimers (2). The halide bibridged chains expand their primary copper coordination spheres to give 4 + 2 coordination spheres in 1 and 2 . In 3, the layer structure involves coordination of the hydrogen bonded L'(2) dimers and C-(BrBr-)-Br-... interactions. Crystal data: (1): monoclinic, P2(1)/m, a=3.929(1), b=12.373(2), c=7.050(1)Angstrom, beta=91.206(4)degrees, V= 342.7(1)Angstrom(3), Z= 2, D-calc = 2.225 Mg/m(3), mu.= 3.878 mm(-1), R = 0.0269 for [\I\ greater than or equal to 3sigma(I)]. For (2): triclinic, P-1, a=4.095(4), b=7.309(5), c=10.123(6) Angstrom, alpha=86.28(6), beta=78.44(6), gamma=74.55(8)degrees, V=286.1(4) Angstrom(3), Z =, D-calc = 1.884 Mg/m(3), mu = 2.360 mm(-1), R = 0.0506 for [\I\ greater than or equal to 2sigma(I)]. For (3): triclinic P-1 a = 6.074(4), b=7.673(3), c-8.887(3) Angstrom, alpha=108.43(3) beta=100.86(5), gamma=106.96(4)degrees, V=357.0(3) Angstrom(3), Z = 1, d(calc) = 2.657 Mg/m(3), mu=12.714mm(-1), R=0.0409 for [\I\ greater than or equal to 2sigma(I)].