Solid-state interconversions: Unique 100% reversible transformations between the ground and metastable states in single-crystals of a series of nickel( II) nitro complexes

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)]

C–C σ complexes of rhodium

In this article, the complexes [Rh(Binor-S′)(PR(3))][BAr(4)(F)] (R = (i)Pr, Cy, C(5)H(9)) are described. A combination of x-ray crystallography, NMR spectroscopy, density functional theory, and “atoms in molecules” calculations unequivocally demonstrates that the complexes contain rare examples of metal···C [Image: see text] C agostic interactions. Moreover, they are fluxional on the NMR time scale, undergoing rapid and reversible C [Image: see text] C activation. Kinetic data and calculations point to a bismetallacyclobutane, Rh(V), intermediate

Experimental charge density study into C–C σ-interactions in a Binor-S rhodium complex

Transition-metal complexes containing (C–C)→M s-interactions have potential applications in both catalysis and the activation and cleavage of C–C bonds. Fully characterising the bonding and interactions in complexes containing such (C–C)→M s-interactions is vital to understand their chemical behaviour. As a result a high-resolution experimental X-ray charge density study has been undertaken on [Rh(Binor-S)(PCy3)][HCB11Me11] (Binor-S = 1,2,4,5,6,8-dimetheno-s-indacene) which contains a (C–C)→Rh interaction. The data are analysed using Bader’s “Atoms in Molecules” (AIM) approach with particular attention paid to the interactions around the rhodium centre. The results provide clear evidence for the s(C–C)→Rh interaction in the solid-state which is classified as a weak covalent interaction. These results are supported by theoretical calculations

CCDC 799182: Experimental Crystal Structure Determination

An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures