Different co-ordination behaviour of 1,2-diaminoethane (en) and tetracyanonickelate(II) upon accommodation of polar guest molecules in their metal complex hosts: crystal structures of [M(en)2Ni(CN)4]·2PhNH2(M = Ni, Cu, Zn or Cd) and [{Cd(en)}2(en){Ni(CN)4}2]·4PhOH

Abstract

The single-crystal structures have been determined for aniline and phenol clathrates. Aniline clathrates [M(en)₂Ni(CN)₄]·2PhNH₂(M = Ni, Cu, Zn or Cd; en = 1,2-diaminoethane) are isomorphous, having monoclinic space group P2₁/c(Z= 2). The unit cell parameters a, b, c and β, and R index for the reflections used are: M = Ni, 9.452(3), 10.125(3), 13.440(3)Å and 107.27(2)°, 0.0443 for 1806; for M = Cu, 9.547(4), 10.621(5), 12.746(3)Å and 107.89(2)°, 0.0635 for 1861; for M = Zn, 9.550(3), 10.407(2), 13.026(2)Å and 107.50(1)°, 0.0513 for 1758; and for M = Cd, 9.924(2), 10.545(3), 12.510(1)Å and 107.63(1)° 0.0456 for 1829. The guest PhNH₂ molecules are accommodated among [–M(en)₂–NC–Ni(CN)₂–CN–]_n chains extending along the b axis. The bis(en)-chelated M atoms are linked with trans-di-µ-cyano-dicyanonickelate(II) moieties alternately, and adopt an elongated octahedral configuration along the chain. The phenol clathrate [{Cd(en)}₂(en){Ni(CN)₄}₂]·4PhOH belongs to the triclinic system, space group P, with a= 11.868(1), b= 13.030(1), c= 7.7113(6)Å, α= 105.956(7), β= 94.951(8), γ= 91.584(9)°, Z= 1 and R= 0.0410 for 4095 reflections. Three kinds of crystallographically independent PhOH molecules are enclathrated in the three-dimensional host framework in which the en-chelated Cd atoms are linked with infinite [〉Ni〈(CN–Cd–NC–)₂]_n chains and Cd–NC–Ni(CN)₂–CN–Cd and Cd–en–Cd bridges. Interhost, interguest and host–guest hydrogen-bond formation stabilize the whole crystal structures, which are compared with those of [M(en)₂Ni(CN)₄] complexes and the [Cd(en)Ni(CN)₄]·2C₆H₆ clathrate.