Solid‐State Interconversions: Unique 100 % Reversible Transformations between the Ground and Metastable States in Single‐Crystals of a Series of Nickel(II) Nitro Complexes |
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| Authors: | Dr Mark R Warren Dr Timothy L Easun Dr Simon K Brayshaw Prof Robert J Deeth Prof Michael W George Dr Andrew L Johnson Dr Stefanie Schiffers Dr Simon J Teat Dr Anna J Warren Dr John E Warren Prof Chick C Wilson Dr Christopher H Woodall Prof Paul R Raithby |
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| Institution: | 1. Department of Chemistry, University of Bath, Bath, BA2 7AY (UK);2. The Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxon, OX11 0FA (UK);3. Department of Chemistry, University of Nottingham, Nottingham NG7 2RD (UK);4. Department of Chemistry, University of Warwick, Coventry CV4 7AL (UK);5. Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley CA 94720 (USA);6. STFC Daresbury Laboratory, Daresbury, Warrington WA4 4AD (UK) |
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| Abstract: | The solid‐state, low‐temperature linkage isomerism in a series of five square planar group 10 phosphino nitro complexes have been investigated by a combination of photocrystallographic experiments, Raman spectroscopy and computer modelling. The factors influencing the reversible solid‐state interconversion between the nitro and nitrito structural isomers have also been investigated, providing insight into the dynamics of this process. The cis‐Ni(dcpe)(NO2)2] ( 1 ) and cis‐Ni(dppe)(NO2)2] ( 2 ) complexes show reversible 100 % interconversion between the η1‐NO2 nitro isomer and the η1‐ONO nitrito form when single‐crystals are irradiated with 400 nm light at 100 K. Variable temperature photocrystallographic studies for these complexes established that the metastable nitrito isomer reverted to the ground‐state nitro isomer at temperatures above 180 K. By comparison, the related trans complex Ni(PCy3)2(NO2)2] ( 3 ) showed 82 % conversion under the same experimental conditions at 100 K. The level of conversion to the metastable nitrito isomers is further reduced when the nickel centre is replaced by palladium or platinum. Prolonged irradiation of the trans‐Pd(PCy3)2(NO2)2] ( 4 ) and trans‐Pt(PCy3)2(NO2)2] ( 5 ) with 400 nm light gives reversible conversions of 44 and 27 %, respectively, consistent with the slower kinetics associated with the heavier members of group 10. The mechanism of the interconversion has been investigated by theoretical calculations based on the model complex Ni(dmpe)Cl(NO2)]. |
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| Keywords: | linkage isomerism metastable compounds nickel photocrystallography single‐crystals |
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