A solid-state NMR investigation of the colossal expansion material, Ag3Co(CN)(6)

作者：Feland Brett C; Bernard Guy M; Wasylishen Roderick E^*

来源：Canadian Journal of Chemistry, 2012, 90(10): 891-901.

DOI：10.1139/V2012-072

• colossal expansion material
• solid-state NMR
• Co-59 NMR
• C-13 NMR
• N-15 NMR

Presented here is a solid-state NMR investigation of the so-called "colossal expansion" material, Ag3Co(CN)(6), a compound that exhibits some of the largest positive and negative thermal expansion properties reported. This study explores the C-13, N-15, and Co-59 NMR properties of this material at room temperature and at variable temperatures with the goal of probing the effects of this colossal expansion behaviour on these properties. We found that the flexible nature of the crystal framework leads to a distribution of electric field gradients, and that, oddly enough, no strong correlation is observed between the NMR parameters of Ag3Co(CN)(6) and its colossal expansion nature. The Co-59 isotropic chemical shift increased and the Co-59 nuclear quadrupolar coupling constant decreased with increasing temperature, but neither of these relationships were extraordinary when compared to other octahedral Co(III) complexes. The link between the colossal expansion and the NMR properties of Ag3Co(CN)(6) may be the distribution of lattice parameters and hence unusually broad features in the Co-59 NMR spectra. The high order of symmetry at the cobalt site resulted in a small quadrupolar coupling constant less than 1 MHz in magnitude. We also observed a vertical bar(1)J(Ag-107/109,N-15)vertical bar value of 96 Hz, the largest Ag-107/109-N-15 coupling constant reported to date.

• 出版日期2012-10