Cardiff University | Prifysgol Caerdydd ORCA
Online Research @ Cardiff 
WelshClear Cookie - decide language by browser settings

Thermal and photochemical control of nitro-nitrito linkage isomerism in single-crystals of [Ni(medpt)(NO2)(η2-ONO]

Hatcher, Lauren E. ORCID:, Bigos, Edward J., Bryant, Mathew J., MacCready, Emily M., Robinson, Thomas P., Saunders, Lucy K., Thomas, Lynne H., Beavers, Christine M., Teat, Simon J., Christensen, Jeppe and Raithby, Paul R. 2014. Thermal and photochemical control of nitro-nitrito linkage isomerism in single-crystals of [Ni(medpt)(NO2)(η2-ONO]. CrystEngComm 16 (35) 10.1039/C4CE00675E

Full text not available from this repository.


The known complex [Ni(medpt)(η1-NO2)(η2-ONO)] 1 (medpt = 3,3′-diamino-N-methyldipropylamine) crystallises in the monoclinic space group P21/m with 1.5 molecules in the asymmetric unit with two different η1-NO2 ligand environments in the crystal structure. At 298 K the molecule (A) sitting in a general crystallographic site displays a mixture of isomers, 78% of the η1-NO2 isomer and 22% of an endo-nitrito–(η1-ONO) form. The molecule (B) sitting on a crystallographic mirror plane adopts the η1-NO2 isomeric form exclusively. However, a variable temperature crystallographic study showed that the two isomers were in equilibrium and upon cooling to 150 K the η1-ONO isomer converted completely to the η1-NO2 isomer, so that both independent molecules in the asymmetric unit were 100% in the η1-NO2 form. A kinetic analysis of the equilibrium afforded values of ΔH = −9.6 (±0.4) kJ mol−1, ΔS = −21.5 (±1.8) J K−1 mol−1 and EA = −1.6 (±0.05) kJ mol−1. Photoirradiation of single crystals of 1 with 400 nm light, at 100 K, resulted in partial isomerisation of the η1-NO2 isomer to the metastable η1-ONO isomer, with 89% for molecule (A), and 32% for molecule (B). The crystallographic space group also reduced in symmetry to P21 with Z′ = 3. The metastable state existed up to a temperature of 150 K above which temperature it reverted to the ground state. An analysis of the crystal packing in the ground and metastable states suggests that hydrogen bonding is responsible for the difference in the conversion between molecules (A) and (B).

Item Type: Article
Date Type: Publication
Status: Published
Schools: Chemistry
Publisher: Royal Society of Chemistry
ISSN: 1466-8033
Date of Acceptance: 20 June 2014
Last Modified: 07 Nov 2022 09:52

Actions (repository staff only)

Edit Item Edit Item