Energetics, thermal isomerisation and photochemistry of the linkage-isomer system [Ni(Et₄dien)(η²-O,ON)(η¹-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.