| Autor: |
Ahmed M; School of Chemistry, The University of New South Wales, Sydney, 2052, Australia. s.neville@unsw.edu.au., Brand HEA; The Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria, Australia., Peterson VK; ANSTO, Lucas Heights, New South Wales, Australia., Clegg JK; School of Chemistry and Molecular Biosciences, The University of Queensland, St Lucia, Queensland 4072, Australia., Kepert CJ; The School of Chemistry, The University of Sydney, Sydney, 2006, Australia., Price JR; School of Chemistry, The University of New South Wales, Sydney, 2052, Australia. s.neville@unsw.edu.au and The Australian Synchrotron, 800 Blackburn Road, Clayton, Victoria, Australia., Powell BJ; School of Mathematics and Physics, The University of Queensland, St Lucia, Queensland 4072, Australia., Neville SM; School of Chemistry, The University of New South Wales, Sydney, 2052, Australia. s.neville@unsw.edu.au. |
| Abstrakt: |
An extended nitro-functionalised 1,2,4-triazole ligand has been used to induce considerable lattice distortion in a 2-D Hofmann framework material via competing supramolecular interactions. Single crystal X-ray diffraction analyses on [Fe3(N-cintrz)6(Pd(CN)4)3]·6H2O (N-cintrz: (E)-3-(2-nitrophenyl)acrylaldehyde) reveal a substantial deviation from a regular Hofmann structure, in particular as the intra- and inter-layer contacts are dominated by hydrogen-bonding interactions rather than the typical π-stacking arrays. Also, the 2-D Hofmann layers show an assortment of ligand conformations and local FeII coordination environments driven by the optimisation of competing supramolecular contacts. Temperature-dependent magnetic susceptibility measurements reveal a two-step spin crossover (SCO) transition. Variable temperature structural analyses show that the two crystallographically distinct FeII centres, which are arranged in stripes (2 : 1 ratio) within each Hofmann layer, undergo a cooperative HS ↔ HS/LS ↔ LS (HS = high spin, LS = low spin) transition without periodic spin-state ordering. The mismatch between crystallographic (2 : 1) and spin-state (1 : 1) periodicity at the HS : LS step provides key insight into the competition (frustration) between elastic interactions and crystallographically driven order. |
