Microwave measurements of 14N and D quadrupole coupling for (Z)-2-hydroxypyridine and 2-pyridone tautomers
Microwave measurements of 14N and D quadrupole coupling for (Z)-2-hydroxypyridine and 2-pyridone tautomers
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DOI：
10.1021/jp046949f
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发表时间：
2004-11-04
影响因子：
2.9
通讯作者：
Kukolich, SG
中科院分区：
文献类型：
--
作者：
Tanjaroon, C;Subramanian, R;Kukolich, SG
用脉冲束傅立叶变换微波光谱仪测量了两种互变异构体(Z)-2-羟基吡啶和2-吡啶酮及其氘化同位素体在4 ~ 14 GHz微波范围内的旋转光谱。氮和氘的四极子超精细结构在许多观察到的跃迁中被完全解决，并且这两种互变异构体的N-14四极子耦合张量是完全不同的。eQq(cc)(N)的符号相反。(Z)-2-羟基吡啶在主惯性轴系中的N-14四极耦合强度为：eQq(aa)(N) = -0.076(11), eQq(bb)(N) = -2.283(6), eQq(cc)(N) = 2.359(6) MHz。(Z)-2-氘-羟基吡啶在主惯性轴上的N-14和D核四极耦合强度分别为eQq(aa)(N) = -0.1465(4), eQq(bb)(N) = -2.2045(4), eQq(cc)(N) = 2.3510(4) MHz, eQq(aa)(D) = -0.0250(9), eQq(bb)(D) = 0.1699(4), eQq(cc)(D) = -0.1449(4) MHz。2-吡啶酮在主惯性轴系中的14N四极耦合强度分别为：eQq(aa)(N) = 1.496(4), eQq(bb)(N) = 1.269(4), eQq(cc)(N) = -2.765(4) MHz。主惯性轴系中1-氘-2-吡啶酮的N-14和D核四极耦合强度分别为：eQq(aa)(N) = 1.511(2), eQq(bb)(N) = 1.249(5), eQq(cc)(N) = -2.759(5) MHz, eQq(aa)(D) = -0.110(7), eQq(bb)(D) = 0.354(6), eQq(cc)(D) = -0.244(6) MHz。得到了两种互变异构体的H和D同位素体的新的、改进的实验旋转常数。Kraitchman分析表明，2-羟基吡啶和2-吡啶的互变异构体氢原子离质心的距离分别为2.653(2)埃和2.124(1)埃。DFT计算的互变异构体和氘化互变异构体的eQq(N)值与目前的实验值吻合较好。用towes - dailey模型分析了互变异构体的新四极耦合数据，并以氮原子p轨道占用数的形式给出了结果。
Rotational spectra for the two tautomers (Z)-2-hydroxypyridine and 2-pytidone and their deuterated isotopomers were measured in the microwave range between 4 and 14 GHz using a pulsed beam Fourier transform microwave spectrometer. Nitrogen and deuterium quadrupole hyperfine structure was completely resolved for many of the observed transitions, and the measured N-14 quadrupole coupling tensors are quite different for these two tautomers. The eQq(cc)(N) values have opposite signs. The N-14 quadrupole coupling strengths for (Z)-2-hydroxypyridine in the principal inertial axis system are as follows: eQq(aa)(N) = -0.076(11), eQq(bb)(N) = -2.283(6), and eQq(cc)(N) = 2.359(6) MHz. The N-14 and D nuclear quadrupole coupling strengths for (Z)-2-deuteriohydroxypyridine in the principal inertial axis are eQq(aa)(N) = -0.1465(4), eQq(bb)(N) = -2.2045(4), and eQq(cc)(N) = 2.3510(4) MHz and eQq(aa)(D) = -0.0250(9), eQq(bb)(D) = 0.1699(4), and eQq(cc)(D) = -0.1449(4) MHz. The 14N quadrupole coupling strengths for 2-pyridone in the principal inertial axis system are eQq(aa)(N) = 1.496(4), eQq(bb)(N) = 1.269(4), and eQq(cc)(N) = -2.765(4) MHz. The N-14 and D nuclear quadrupole coupling strengths for 1-deuterio-2-pyridone in the principal inertial axis system are as follows: eQq(aa)(N) = 1.511(2), eQq(bb)(N) = 1.249(5), and eQq(cc)(N) = -2.759(5) MHz and eQq(aa)(D) = -0.110(7), eQq(bb)(D) = 0.354(6), and eQq(cc)(D) = -0.244(6) MHz. New, improved, experimental rotational constants were obtained for the H and D isotopomers of both tautomers. Kraitchman analysis indicates the "tautomeric" hydrogen atom is at a distance of 2.653(2) Angstrom in 2-hydroxypyridine and a distance of 2.124(1) Angstrom in 2-pyridone from the centers of mass of the two tautomers, respectively. The DFT calculated eQq(N) values for both the tautomers and the deuterated tautomers are in good agreement with the present experimental values. The Townes-Dailey model has been used to analyze the new quadrupole coupling data of the tautomers and the results are presented in terms of nitrogen atom p-orbital occupation numbers.