Определение цис и транс комплесов ЯМР

[shagrath]

Подскажите пожалуйста можно ли по ПМР спектру вещества определить является ли он цис или транс комплексом, как например в случае плоскоквадратных комплексов платины

[eukar]

Про платину конкретно не знаю, а вообще можно.

[mitsu]

Можно, причем, как правило, это достаточно тривиальная задача.

[slavert]

Если с фосфорными лигандами комплексы платины то очень просто...

[shagrath]

комплексы платины следующего типа [PtCl2(DMSO)(pic)]
Сняли несколько ЯМР, в первом случае получили чистое вещество во втором на фоне этого же вещества была примесь ( как предпологается другой изомер). Нужно соотнести какая картинка относится к транс а какая к цис

[slavert]

Bibliographic Information

Reaction of dichlorobis(dimethyl sulfoxide)platinum(II) with pyridine and isomerization of dichloro(dimethyl sulfoxide)(pyridine)platinum(II). Kong, Pi-Chang; Iyamuremye, Daniel; Rochon, F. D. Dep. Chim., Univ. Quebec, Montreal, QC, Can. Canadian Journal of Chemistry (1976), 54(20), 3224-6.

Abstract

The reaction between cis-[Pt(DMSO)2Cl2] (DMSO = dimethyl sulfoxide) and pyridine, picoline, and lutidine was studied by NMR techniques. The results obtained with 4-picoline (4-pic) are discussed. Trans-[Pt(4-pic)(DMSO)Cl2] is 1st formed and then isomerizes to a mixt. of isomers, i.e., cis-[Pt(DMSO)2Cl2] + 4-pic ® trans-[Pt(DMSO)(4-pic)Cl2] .dblarw. cis-[Pt(DMSO)(4-pic)Cl2]. An effective method to prepare cis isomers was derived from this study. The advantages of the new method are discussed.


Bibliographic Information

Thermal and photochemical cis-trans isomerization of PtL2Cl2 (L = dialkyl sulfoxide) complexes. Kinetics and mechanisms for thermal isomerization. Price, Jerold H.; Birk, James P.; Wayland, Bradford B. E. F. Smith Lab. Chem., Univ. Pennsylvania, Philadelphia, PA, USA. Inorganic Chemistry (1978), 17(8 ), 2245-50.
Abstract

Trans-Pt(Pr2SO)2Cl2 was isolated as a solid kinetic product where the cis form is the thermodn. stable species. Photolyzing CDCl3 solns. contg. predominantly cis isomers of Pt(MeSO)2Cl2, Pt(Et2SO)2Cl2, and Pt(Pr2SO)2Cl2 results in enrichment of the trans isomer. The 3 trans complexes thermally isomerize in soln. to cis-trans equil. mixts. The forward, kf, and reverse, kr, rate consts. were detd. by NMR for the 1st-order kinetic process trans-Pt(L)2Cl2 .dblarw. cis-Pt(L)2Cl2 where L = Et2SO or Pr2SO. Temp. dependence of the rate consts. suggests the trans isomer is enthalpy favored, and the cis isomer entropy favored. Free-ligand addns. to isomerizing trans-Pt(Pr2SO)2Cl2 solns. permit several mechanisms to be proposed for the isomerization. The interchange in Pt(L)2Cl2 solns. of Me2SO for Et2SO and Am2SO, where Am2SO = diisoamyl sulfoxide, was followed by proton NMR. These interchanges occur with retention of geometric configuration. The intermediate Pt(Me2SO)(L)Cl2 complexes and the thermal isomerization of these intermediates are described.

[shagrath]

Bibliographic Information

Reaction of dichlorobis(dimethyl sulfoxide)platinum(II) with pyridine and isomerization of dichloro(dimethyl sulfoxide)(pyridine)platinum(II). Kong, Pi-Chang; Iyamuremye, Daniel; Rochon, F. D. Dep. Chim., Univ. Quebec, Montreal, QC, Can. Canadian Journal of Chemistry (1976), 54(20), 3224-6.

Abstract

The reaction between cis-[Pt(DMSO)2Cl2] (DMSO = dimethyl sulfoxide) and pyridine, picoline, and lutidine was studied by NMR techniques. The results obtained with 4-picoline (4-pic) are discussed. Trans-[Pt(4-pic)(DMSO)Cl2] is 1st formed and then isomerizes to a mixt. of isomers, i.e., cis-[Pt(DMSO)2Cl2] + 4-pic ® trans-[Pt(DMSO)(4-pic)Cl2] .dblarw. cis-[Pt(DMSO)(4-pic)Cl2]. An effective method to prepare cis isomers was derived from this study. The advantages of the new method are discussed.


Bibliographic Information

Thermal and photochemical cis-trans isomerization of PtL2Cl2 (L = dialkyl sulfoxide) complexes. Kinetics and mechanisms for thermal isomerization. Price, Jerold H.; Birk, James P.; Wayland, Bradford B. E. F. Smith Lab. Chem., Univ. Pennsylvania, Philadelphia, PA, USA. Inorganic Chemistry (1978), 17(8), 2245-50.
Abstract

Trans-Pt(Pr2SO)2Cl2 was isolated as a solid kinetic product where the cis form is the thermodn. stable species. Photolyzing CDCl3 solns. contg. predominantly cis isomers of Pt(MeSO)2Cl2, Pt(Et2SO)2Cl2, and Pt(Pr2SO)2Cl2 results in enrichment of the trans isomer. The 3 trans complexes thermally isomerize in soln. to cis-trans equil. mixts. The forward, kf, and reverse, kr, rate consts. were detd. by NMR for the 1st-order kinetic process trans-Pt(L)2Cl2 .dblarw. cis-Pt(L)2Cl2 where L = Et2SO or Pr2SO. Temp. dependence of the rate consts. suggests the trans isomer is enthalpy favored, and the cis isomer entropy favored. Free-ligand addns. to isomerizing trans-Pt(Pr2SO)2Cl2 solns. permit several mechanisms to be proposed for the isomerization. The interchange in Pt(L)2Cl2 solns. of Me2SO for Et2SO and Am2SO, where Am2SO = diisoamyl sulfoxide, was followed by proton NMR. These interchanges occur with retention of geometric configuration. The intermediate Pt(Me2SO)(L)Cl2 complexes and the thermal isomerization of these intermediates are described.

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[slavert]

одной есть, в exchange

[Сержл]

Подскажите пожалуйста можно ли по ПМР спектру вещества определить является ли он цис или транс комплексом, как например в случае плоскоквадратных комплексов платины

Обычно это делают по ИК, нужна структура комплекса, что бы подсказать точнее какие ядра в ЯМР снимать, можно по константе посмотреть и характерному хим сдвигу, согласно лит данным.

Лови ссылочку по комплексам платины и др, может поможет.
http://dx.doi.org/10.1016/j.molcata.2006.06.025