Journal of the American Chemical Society p. 4912 - 4915 (1983)
Update date:2022-08-30
Topics:
Meot-Ner (Mautner), Michael
Complexes of ammonium ions RNH3+ (R = CH3, c-C6H11), (CH3)3NH+, and pyridineH+ with polyethers and crown ethers are observed in the gas phase in the abscence of the solvent effects.The dissociation energies, ΔH0D, of the RNH3+ polyether complexes range from 29.4 kcal mol-1 (for RNH3+*CH3OCH2CH2OCH3) to 46 kcal mol-1 (RNH3+*18-crown-6).The large ΔH0D values for complexes of polydentate ligands indicate multiple -NH+...O-hydrogen bonding.Such mutiple bonding can contribute up to 18 kcal mol-1 to the bonding in RNH3+*CH3(OCH2CH2)3OCH3 and 21 kcal mol-1 in RNH3+*18-crown-6.Multiple interactions are also evident in the (CH3)3NH+*polyether complexes where -CH?+...O-hydrogen bonding seems to occur; and consecutive -CH?+...O-bonds contribute approximately 6, 4, and 2 kcal/mol-1 respectively for up to three such bonds.Total ΔH0D values in the (CH3)3NH+*polyether complexes thus range from 26.7 kcal mol-1 in (CH3)3NH+*CH3O(CH2)2OCH3 to 41 kcal mol-1 in (CH3)3NH+*18-crown-6.Multiple interaction effects, possibly including van der Waals dispersion forces, are observed also in pyridineH+*polyether complexes.Large negative entropies in RNH3+*acyclic polyether complexes vs.RNH3+*cyclic crown ethers make the acyclic polyethers less efficient ligands.
View Moresuzhou chukai pharmateach co,.ltd
Contact:86-512-88812511
Address:Building 3, Wujiang Scientific Innovation Park, 2358 Changan Rd, Wujiang 215200, Jiangsu Province, P. R. China
SHENYANG COMEBOARD TECHNOLOGY CO., LTD
Contact:+86-24-25724626
Address:Room2210,Tianbao International Building,No.8-1 Weigong South Street,Tiexi District,Shenyang,China
Xi'an HO-SHINE Bio-Technology Co., Ltd
Contact:+86 (29) 8248-5435/18292020086
Address:No.6 Shiyuan Road Xian City Shaanxi Province, 710048 China
Melone Pharmaceutical Co., ltd
Contact:+86-411 82593920, 82593631
Address:No 232, JInma Roda, Development Zone, Dalian, China
LIAOYANG WANRONG CHEMICALS COMPANY LIMITED
Contact:86-419-2390789
Address:XINLI VILLAGE , DONG NINGWEI COUNTY,TAIZIHE DISTRICT, LIAOYANG , LIAONING
Doi:10.1039/c7cc05570f
(2017)Doi:10.1021/jo961069l
(1996)Doi:10.1016/0039-128X(80)90071-9
(1980)Doi:10.1021/acs.joc.6b02404
(2016)Doi:10.1016/S0040-4039(01)81602-6
(1984)Doi:10.1023/A:1013456112725
(2001)