Duarte Luís, Rekola Iiris, Khriachtchev Leonid
Department of Chemistry, University of Helsinki , P.O. Box 55, FI-00014 Helsinki, Finland.
J Phys Chem A. 2017 Nov 16;121(45):8728-8737. doi: 10.1021/acs.jpca.7b09586. Epub 2017 Nov 7.
The complex of formic acid (FA, HCOOH) with nitrous oxide (NO) was studied experimentally and computationally. Eight structures of the trans-FA···NO complex and nine structures of the cis-FA···NO complex were found at the density functional theory (M06-2X and wB97XD), MP2(full), and CCSD(T)-F12a levels. Two structures of the trans-FA···NO complex (1t and 3t) and two structures of the cis-FA···NO complex (1c and 3c) were identified by infrared spectroscopy in an argon matrix. Structure 1t with the bonded OH group appears in the matrices after deposition. Structures 3t and 3c with the free OH groups were prepared by vibrational excitation of the trans-FA conformer in structures 1t and 3t, respectively. Structure 3t is thermally unstable and relaxes to structure 1t at ∼15 K. Structure 1c with the bonded OH group is made by vibrational excitation of trans-FA monomer combined with thermal annealing. The lifetimes of the cis-FA···NO complex structures 1c (81.5 min) and 3c (18.7 min) in an argon matrix at 4.3 K are longer than that of cis-FA monomer (6.3 min). This difference agrees with the calculated stabilization barriers of these species.
对甲酸（FA，HCOOH）与一氧化二氮（NO）的复合物进行了实验和计算研究。在密度泛函理论（M06 - 2X和wB97XD）、MP2（全电子）和CCSD（T）-F12a水平上发现了反式-FA···NO复合物的八种结构和顺式-FA···NO复合物的九种结构。通过氩气基质中的红外光谱鉴定了反式-FA···NO复合物的两种结构（1t和3t）和顺式-FA···NO复合物的两种结构（1c和3c）。沉积后，基质中出现带有键合OH基团的结构1t。分别通过结构1t和3t中反式-FA构象异构体的振动激发制备了带有游离OH基团的结构3t和3c。结构3t热不稳定，在约15 K时弛豫为结构1t。带有键合OH基团的结构1c是通过反式-FA单体的振动激发结合热退火制备的。在4.3 K的氩气基质中，顺式-FA···NO复合物结构1c（81.5分钟）和3c（18.7分钟）的寿命比顺式-FA单体（6.3分钟）的寿命长。这种差异与这些物种的计算稳定能垒一致。
