Two crystal systems: [Pd(Et₄dien)(NO₂)]OTf [1] and [Pt(Et₄dien)(NO₂)]OTf [2] (Et₄dien = N,N,N′,N′-tetraethyldiethylene-triamine, OTf = trifluoromethanesulfonate) are investigated by steady-state photocrystallographic methods. Both structures contain intermolecular hydrogen bonds to the ground state nitro-(η¹-NO₂) isomer, which are previously shown to limit the achievable level of nitro → nitrito photo-conversion. Irradiation at 100 K induces a mixture of endo-ONO and exo-ONO isomers in 1 and 2, with overall incomplete photo-activation. In contrast, irradiation at higher temperatures leads to much higher conversion, with 100% excitation in 1 at 150 K. The results show that the detrimental effects of hydrogen bonding on the photo-reaction are overcome at higher temperature, adding a new dimension of control to the isomerisation process.

中文翻译：

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氢键对固态硝基硝腈键异构体中100％光开关的影响

两个晶体系统：[Pd（Et ₄ dien）（NO ₂）] OTf [ 1 ]和[Pt（Et ₄ dien）（NO ₂）] OTf [ 2 ]（Et ₄ dien = N，N，N '，N通过稳态光晶体学方法研究了'-四乙基二亚乙基三胺（OTf =三氟甲磺酸盐）。两种结构都包含分子间氢键到基态硝基- （η ¹ -NO ₂被先前表明限制硝基的可实现的水平→nitrito光转换）异构体。在100 K的辐射下会产生内-ONO和1和2中的exo -ONO异构体，总体具有不完全的光活化作用。相反，在较高的温度下辐照会导致更高的转化率，在150 K下以1的100％激发。结果表明，在较高的温度下可以克服氢键对光反应的不利影响，从而增加了控制的新维度。异构化过程。