In situ FT-IR and UV-vis spectroscopy of the low-temperature NO disproportionation mediated by solid state manganese(II) porphyrinates.
In situ FT-IR and UV-vis spectroscopy of the low-temperature NO disproportionation mediated by solid state manganese(II) porphyrinates.
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DOI：
10.1021/ic051824q
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发表时间：
2006-04
影响因子：
4.6
通讯作者：
G. G. Martirosyan-G.;A. S. Azizyan;T. Kurtikyan;P. Ford
中科院分区：
文献类型：
--
作者：
G. G. Martirosyan-G.;A. S. Azizyan;T. Kurtikyan;P. Ford
在77 K至室温的温度范围内，用红外光谱和光谱学监测了NO气体与锰（II）卟啉酸盐络合物Mn(Por) (Por = TPP（四苯基卟啉酸）、TMP（四烷基卟啉酸）或TPP(d20)（过氘化四苯基卟啉酸）升华层之间的非均相反应。这些锰卟啉促进NO歧化为NO2和N2O，反应经过几个不同的阶段进行。在90k时，光谱上观察到的主要物质是一氧化氮二聚体、顺式onno、两个锰亚硝基、简单NO加合物Mn(Por)（NO）和另一个对歧化机制明显至关重要的中间体(1)。这种关键中间体是在N2O演化之前形成的，并提出了有关其可能结构的建议。当体系升温至130 K时，歧化产物N2O和o配位亚硝酸盐配合物Mn(Por)(NO)(ONO)(2)生成。红外光谱变化表明，当温度进一步升高到200 K时，2异构成n键硝基异构体Mn(Por)(NO)(NO2)(3)。加热至室温后，后者失去NO，转化为已知的5坐标亚硝酸盐配合物Mn(Por)(ONO)(4)。
The heterogeneous reaction between NO gas and sublimed layers of manganese(II) porphyrinato complexes Mn(Por) (Por = TPP (tetraphenylporphyrinato dianion), TMP (tetramesitylporphyrinato dianion), or TPP(d20) (perdeuterated tetraphenylporphyrinato dianion)) has been monitored by IR and optical spectroscopy over the temperature range of 77 K to room temperature. These manganese porphyrins promote NO disproportionation to NO2 species and N2O, and the reaction proceeds via several distinct stages. At 90 K, the principal species observed spectrally are the nitric oxide dimer, cis-ONNO, two manganese nitrosyls, the simple NO adduct Mn(Por)(NO), and another intermediate (1) that is apparently critical to the disproportionation mechanism. This key intermediate is formed prior to N2O evolution, and proposals regarding its likely structure are offered. When the system is warmed to 130 K, the disproportionation products, N2O and the O-coordinated nitrito complex Mn(Por)(NO)(ONO) (2), are formed. IR spectral changes show that, upon further warming to 200 K, 2 isomerizes into the N-bonded nitro linkage isomer Mn(Por)(NO)(NO2) (3). After it is warmed to room temperature, the latter species loses NO and converts to the known 5-coordinate nitrito complex Mn(Por)(ONO) (4).