Photoactivated linkage isomerism in single crystals of nickel, palladium and platinum di-nitro complexes

M.R. Warren, S.K. Brayshaw, L.E. Hatcher, A.L. Johnson, S. Schiffers, A.J. Warren, C.H. Woodall, P.R. Raithby, S.J. Teat, J.E. Warren

OAI: oai:purehost.bath.ac.uk:openaire_cris_publications/fd7d5e01-6504-40a3-8566-7485016df1c6 • DOI: https://doi.org/10.1039/c2dt30314k

Low temperature, single crystal photocrystallographic studies have been carried out on four square planar Group 10 complexes Ni(PEt 3) 2(NO 2) 2] 1, [Pd(PPh 3) 2(NO 2) 2] 2, [Pd(AsPh 3) 2(NO 2) 2] 3 and [Pt(PPh 3) 2(NO 2) 2] 4 in which the two nitro groups adopt the trans configuration. Irradiation with UV light, at 100 K, of single crystals of complexes 1-3 photoisomerise from the from the η 1-NO 2 nitro form to the η 1-ONO nitrito form occurred. Complex 1 underwent 25% conversion to the nitrito form before crystal decomposition occurred. 2 and 3 underwent 46% and 39% conversion, respectively, to the nitrito form when a photostationary state was reached. While under the same experimental conditions 4 showed no isomerisation. The photocrystallographic results can be correlated with the results of DFT calculations and with the observed trends in the solution UV/visible absorption spectroscopy obtained for these complexes. The results suggest that while steric factors in the isomerization processes are important there may also be a kinetic effect relating to the lability of the metal involved.