Non-centrosymmetric CuSCN based coordination polymers with substituted pyrazine and pyrimidine ligands

Non-centrosymmetric one- to three-dimensional CuSCN-based coordination poly mers with substituted pyrazine or pyrimidine spacer ligands can be prepared by self-assembly in acetonitrile solution at 100 degrees C. Both (1)(infin ity)[CuSCN(2NCpyz)(2)] (1) (2NCpyz = 2-cyanopyrazine) and (1)(infinity)[CuS CN(4HOpym)(2)] (3) (4 HOpym = 4-hydroxypyrimidine) contain single zigzag Cu SCN chains as their central backbone and crystallise in polar space groups (monoclinic Cm and orthorhombic Ama2). In (2)(infinity)[(CuSCN)(2)(mu-2 Mep yz)] (2 (2 Mepyz = 2-methylpyrazine), (1)(infinity)[(CuSCN))(2)] staircase double chains are connected by bridging 2 Mepyz Ligands to afford a lamella r polymer (triclinic <P(1)over bar>. Whereas (2)(infinity)[CuSCN(5 Brpym)] (4) (5 Brpym = 5-bromopyrimidine) with its honeycomb (2)(infinity)[CuSCN] l ayers is chiral (monoclinic P2(1)), both 3D polymers (3)(infinity)(CuSCN)(2 )(mu-pym)] (5) and (2)(infinity)[(CuSCN)(3)(mu-4 Mepym)] (6) (4 Mepym = 4-m ethylpyrimidine) contain polar coordination networks (orthorhombic Fdd2 and monoclinic Pc). The CuSCN framework in (5) consists of thiocyanate bridged (1)(infinity)[CuS] chains, that in 6 of interlocked (2)(infinity)[CuSCN] a nd (2)(infinity)[Cu2S(SCN)] sheets.