Experimental and computational studies of molecules with close, non-bonded hydrogen–hydrogen contacts: common computational methods grossly overestimate some ‘through-space’ NMR scalar coupling constants
摘要:
The NMR spin spin scalar coupling constants (J(HH)'s) of closely contacting, but non-bonded hydrogen atoms in a series of highly strained molecules (including a new in,in-cyclophane made specifically for this study) have been examined both experimentally and computationally. The experimental J(HH)'s are invariably quite small (0.1-0.6 Hz), but common DFT methods with modest basis sets nearly always overestimate these values, by factors of 10-30, and even with quite large basis sets (up to cc-pVQZ) the J(HH)'s of two of the molecules are overestimated by a factor of 10 or more. Possible reasons for these discrepancies are discussed. (C) 2014 Elsevier Ltd. All rights reserved.
The formation of trithiametacyclophanes from the trisodium salt of a tris(mercaptoalkyl)benzene and a trisbromoalkylmethane is described. 1H N.m.r. spectra were used to determine the structures of the products, with the aid of shiftreagents.
描述了由三(巯基烷基)苯的三钠盐和三溴代烷基甲烷形成三硫杂环丁烷。1 H Nmr光谱在转移试剂的帮助下用于确定产物的结构。
Multiple Isomers of a Small, Strained Phosphaphane
作者:Yonglong Xiao、Joel T. Mague、Robert A. Pascal
DOI:10.1002/ejoc.201801106
日期:2018.11.8
the formula (C28H31PS3)n (n = 1, 2) were isolated from a macrocyclization reaction of a triarylphosphine trithiol and a tribromoalkane. X‐ray analysis showed them to be an in,in‐isomer (1), an in,out‐isomer, and an in,out,in,out‐dimer, and 1 displays strong through‐space coupling of its central atoms.
从三芳基膦三硫醇和三溴代烷烃的大环化反应中分离出三个不同的式(C 28 H 31 PS 3)n(n = 1,2)的环烷。X射线分析表明它们是in,in异构体(1),in,out异构体,in,out,in,out二聚体,并且1显示出中心原子的强空间耦合。
DE842069
申请人:——
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RICCI A.; DANIELI R.; ROSSINI S., J. CHEM. SOC. PERKIN TRANS., PART I <JCPK-BH>, 1976, NO 16, 1691-1693
作者:RICCI A.、 DANIELI R.、 ROSSINI S.
DOI:——
日期:——
Synthesis of Imidazole-Containing Ligands and Studies on Metal Complexes
1,5-Di(imidazol-1-yl)-3-[2-(imidazol-1-yl)ethyl]pentane, 1,7-di(imidazol-1-yl)-4-[3-(imidazol-1-yl)propyl]heptane, N,N′,N″-tris[2-(imidazol-4-yl)ethyl]benzene-1,3,5-tricarboxamide, and 1,3,5-tris[3-(imidazol-1-yl)propyl]benzene (TIPB) have been synthesized for a study of the formation and characteristics of zinc complexes. TIPB forms a crystalline zinc complex, not a tetrahedral complex but an octahedral complex. Other ligands form either microcrystalline complexes or polymer complexes with zinc.