M\"ossbauer, nuclear inelastic scattering and density functional studies on the second metastable state of Na2[Fe(CN)5NO]⋅\cdot2H2O

The structure of the light-induced metastable state SII of Na2[Fe(CN)5NO]$\cdot$2H2O 14 was investigated by transmission M\"ossbauer spectroscopy (TMS) in the temperature range 15 between 85 and 135 K, nuclear inelastic scattering (NIS) at 98 K using synchrotron 16 radiation and density functional theory (DFT) calculations. The DFT and TMS results 17 strongly support the view that the NO group in SII takes a side-on molecular orientation 18 and, further, is dynamically displaced from one eclipsed, via a staggered, to a second 19 eclipsed orientation. The population conditions for generating SII are optimal for 20 measurements by TMS, yet they are modest for accumulating NIS spectra. Optimization 21 of population conditions for NIS measurements is discussed and new NIS experiments on 22 SII are proposed

Energetics, thermal isomerisation and photochemistry of the linkage-isomer system [Ni(Et(4)dien)(eta(2)-O,ON)(eta(1)-NO2)]

We present the results of a detailed theoretical study of the linkage isomerisation in [Ni(Et4dien)(η2-O,ON)(η1-NO2)] (Et4dien = N,N,N′,N′-tetraethyldiethylenetriamine). We probe the structure and bonding of the three experimentally-identified isomers in this system through electronic-structure calculations, and we establish possible transition pathways between them using transition-state modelling and periodic solid-state molecular-dynamics simulations. We also explore the photochemical isomerisation reaction using time-dependent density-functional theory. These results provide a thorough account of the linkage isomerisation in this compound, and add insight to ongoing experimental work on this and related systems