Halogen derivatives of m-phenylene(carbeno)nitrene: a switch in ground-state multiplicity.
Halogen derivatives of m-phenylene(carbeno)nitrene: a switch in ground-state multiplicity.
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间亚苯基（碳烯基）氮烯的卤素衍生物：基态多重性的开关。
DOI：
10.1021/jo025877q
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发表时间：
2002
期刊：
影响因子：
--
通讯作者：
H. Tomioka
中科院分区：
文献类型：
--
作者：
T. Enyo;A. Nicolaides;H. Tomioka
间亚苯基偶联的碳氮烯 [(3-硝基苯基)亚甲基 (2-H)、(3-亚硝基苯基)氟亚甲基 (2-F)、(3-亚硝基苯基)氯亚甲基 (2-Cl)、(3-亚硝基苯基)溴亚甲基 (2-Br)] 已通过计算研究（使用 B3LYP、MCSCF、 CASPT2、ROMP2 和 QCISD(T) 方法）和实验（使用红外、紫外和 ESR 光谱）。对于每个物种，考虑了五种电子态。在探索的最高理论水平上，母体化合物 (2-H) 具有五重基态，但其卤素衍生物（2-X、X = F、Cl 和 Br）具有三重基态。发现2-X的Q[bond]T能隙和相应的苯基卡宾8-X的T-S能隙之间的线性关系，这有助于合理化和预测间亚苯基连接的碳氮烯和类似物质的基态多重性。合成了用于光化学生成 2-X（X = H、F、Cl 和 Br）的前体，并在低温下在基质（Ar、三醋精）中进行光解。 IR（Ar，13 K）和 ESR（三醋精，77 K）数据与三重态卤代碳氮烯 2-X（X = F、Cl 和 Br）的生成一致。正如红外光谱所示，所有四种化合物在进一步照射后都会异构化为取代的环丙烯 5-X（X = H、F、Cl 和 Br）。
m-Phenylene-coupled carbenonitrenes [(3-nitrenophenyl)methylene (2-H), (3-nitrenophenyl)fluoromethylene (2-F), (3-nitrenophenyl)chloromethylene (2-Cl), (3-nitrenophenyl)bromomethylene (2-Br)] have been investigated computationally (with B3LYP, MCSCF, CASPT2, ROMP2, and QCISD(T) methods) and experimentally (with IR, UV, and ESR spectroscopy). For each species, five electronic states were considered. At the highest level of theory explored, the parent compound (2-H) has a quintet ground state, but its halogen derivatives (2-X, X = F, Cl, and Br) have triplet ground states. A linear relationship between the Q[bond]T energy gap of 2-X and the T-S gap of the corresponding phenylcarbenes 8-X is found, which can be helpful in rationalizing and predicting ground-state multiplicities in m-phenylene-linked carbenonitrenes and similar species. Precursors for the photochemical generation of 2-X (X = H, F, Cl, and Br) were synthesized and photolyzed in matrixes (Ar, triacetin) at low temperatures. IR (Ar, 13 K) and ESR (triacetin, 77 K) data are compatible with the generation of triplet halocarbenonitrenes 2-X, (X = F, Cl, and Br). All four compounds upon further irradiation undergo isomerization to substituted cyclopropenes 5-X (X = H, F, Cl, and Br), as suggested by their IR spectra.