Platinum-195 nuclear magnetic resonance spectroscopy (platinum NMR or 195Pt NMR) is a spectroscopic technique which is used for the detection and characterisation of platinum compounds. The sensitivity of the technique and therefore its diagnostic utility have increased significantly starting from the 1970s, with 195Pt NMR nowadays considered the method of choice for structural elucidation of Pt species in solution.[1][2][3]
Examples of compounds routinely characterised with the method include platinum clusters and organoplatinum species such as PtII-based antitumour agents.[2][3] Additional applications of 195Pt NMR include kinetic and mechanistic studies or investigations on drug binding.[2]
Among the naturally occurring isotopes of platinum, 195Pt is the most abundant (33.8%) and the only one with non-zero spinI=1/2.[1][2][3] The magnetic properties of the nucleus are considered favourable; the high natural abundance coupled with a medium gyromagnetic ratio (5.768×107 rad T−1 s−1) result in good 195Pt NMR signal receptivity, 19 times that of 13C (but still only 0.0034 times that of 1H).[2][3]
The resonance frequency (relative to a 100 MHz 1H NMR instrument) is approximately 21.4 MHz, close to the 13C resonance at 25.1 MHz.[1][2]
Chemical shiftsEdit
The chemical shifts of 195Pt nuclei span a very large range of over 13000 ppm (cf. with ~300 ppm range for 13C).[1][2][3] The NMR signals are also very sharp and highly sensitive to the platinum chemical environment (oxidation state, ligand identity and field strength, coordination number, etc.).[1][3] Therefore, substituting even very similar ligands can result in shift changes in the order of hundreds of ppm which stand out on the spectrum and are easily monitored.[2][3]
The reference compound typically chosen for 195Pt NMR experiments is 1.2 M sodium hexachloroplatinate(IV) (Na2PtCl6) in D2O; this platinum(IV) complex is preferred due to its commercial availability, chemical stability, lower price relative to other platinum compounds, and high solubility which enables spectrum recording within minutes.[2][3] Less soluble ionic platinum complexes have spectrum recording times of about an hour, whereas the borderline insoluble neutral complexes may require overnight measurements.[3]
The high sensitivity of the experiment means that contributions from different chlorine isotopes in the reference compound or other species can be resolved at high magnetic field strengths, giving a ±5 ppm uncertainty in reported shift values (which is, however, negligible in view of the 13000 ppm overall range).[1]
195Pt chemical shifts for some common compounds and compound categories[1][2]
Typical J-couplings for 195Pt with other nuclei[2][3]
Nucleus
1J (Hz)
2J (Hz)
3J (Hz)
4J (Hz)
1H
>700
30 to 70
15 to 50
9 to 16
13C
500 to 1800
10 to 55
10 to 40
12 to 15
15N
150 to 350
31P
1500 to 6000
119Sn
>20000
Coupling of 195Pt to 1H, 13C, 31P, 19F or 15N has been reported through one up to four bonds (1J to 4J) and is commonly studied to provide additional structural information for platinum complexes.[2][3] The ~34% abundance of 195Pt (with the remaining 66% of natural Pt being NMR-inactive) means that this coupling appears in the respective 1H/31P/15N/13C NMR spectra as satellite peaks (cf.13C satellites) which, for example, result in 17:66:17 patterns for singlets.[3]
The trans influence in 16 e− square planar PtII complexes has been studied by comparing the magnitude of coupling constants in the cis- and trans- isomers.[2][3]
Complicated homonuclear couplings ranging from 60 to 9000 Hz for 1J(195Pt–195Pt) are of interest in the context of platinum cluster compounds.[3]
ReferencesEdit
^ abcdefgAppleton, Trevor G. (2017-01-01), "NMR Spectroscopy, Heteronuclei, La-Hg", in Lindon, John C.; Tranter, George E.; Koppenaal, David W. (eds.), Encyclopedia of Spectroscopy and Spectrometry (Third Edition), Oxford: Academic Press, pp. 342–345, ISBN978-0-12-803224-4, retrieved 2021-03-23
^ abcdefghijklmStill, Brett M.; Kumar, P. G. Anil; Aldrich-Wright, Janice R.; Price, William S. (2007-03-27). "195Pt NMR—theory and application". Chemical Society Reviews. 36 (4): 665–686. doi:10.1039/B606190G. ISSN 1460-4744. PMID 17387413.
^ abcdefghijklmnPriqueler, Julien R. L.; Butler, Ian S.; Rochon, Fernande D. (2006-07-01). "An Overview of 195Pt Nuclear Magnetic Resonance Spectroscopy". Applied Spectroscopy Reviews. 41 (3): 185–226. Bibcode:2006ApSRv..41..185P. doi:10.1080/05704920600620311. ISSN 0570-4928. S2CID 94037740.
August 31, 2023
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Platinum 195 nuclear magnetic resonance spectroscopy platinum NMR or 195Pt NMR is a spectroscopic technique which is used for the detection and characterisation of platinum compounds The sensitivity of the technique and therefore its diagnostic utility have increased significantly starting from the 1970s with 195Pt NMR nowadays considered the method of choice for structural elucidation of Pt species in solution 1 2 3 Sodium hexachloroplatinate the usual reference compound in 195Pt NMR spectroscopy Examples of compounds routinely characterised with the method include platinum clusters and organoplatinum species such as PtII based antitumour agents 2 3 Additional applications of 195Pt NMR include kinetic and mechanistic studies or investigations on drug binding 2 Contents 1 195Pt magnetic properties 2 Chemical shifts 3 Couplings 4 References195Pt magnetic properties EditAmong the naturally occurring isotopes of platinum 195Pt is the most abundant 33 8 and the only one with non zero spin I 1 2 1 2 3 The magnetic properties of the nucleus are considered favourable the high natural abundance coupled with a medium gyromagnetic ratio 5 768 107 rad T 1 s 1 result in good 195Pt NMR signal receptivity 19 times that of 13C but still only 0 0034 times that of 1H 2 3 The resonance frequency relative to a 100 MHz 1H NMR instrument is approximately 21 4 MHz close to the 13C resonance at 25 1 MHz 1 2 Chemical shifts EditThe chemical shifts of 195Pt nuclei span a very large range of over 13000 ppm cf with 300 ppm range for 13C 1 2 3 The NMR signals are also very sharp and highly sensitive to the platinum chemical environment oxidation state ligand identity and field strength coordination number etc 1 3 Therefore substituting even very similar ligands can result in shift changes in the order of hundreds of ppm which stand out on the spectrum and are easily monitored 2 3 The reference compound typically chosen for 195Pt NMR experiments is 1 2 M sodium hexachloroplatinate IV Na2PtCl6 in D2O this platinum IV complex is preferred due to its commercial availability chemical stability lower price relative to other platinum compounds and high solubility which enables spectrum recording within minutes 2 3 Less soluble ionic platinum complexes have spectrum recording times of about an hour whereas the borderline insoluble neutral complexes may require overnight measurements 3 The high sensitivity of the experiment means that contributions from different chlorine isotopes in the reference compound or other species can be resolved at high magnetic field strengths giving a 5 ppm uncertainty in reported shift values which is however negligible in view of the 13000 ppm overall range 1 195Pt chemical shifts for some common compounds and compound categories 1 2 Compound type Shift range ppm PtII Compound Shift ppm PtIV Compound Shift ppm Pt0 species 550 to 5750 Pt H2O 4 2 30 PtCl6 2 ref 0PtII species 900 to 5750 PtCl4 2 1620 Pt OH 6 2 3280PtIV species 7500 to 6650 PtCl2 NH3 2 2100 Satraplatin 1200 Pt PPh3 2 alkene 500 to 1000 PtBr4 2 2690 PtBr6 2 1860 PtX2L2 X halide L NR3 PR3 SR2 1700 to 5500 PtCl3 C2H4 2750 Pt CN 6 2 3870 Pt CN 4 2 4750Couplings EditTypical J couplings for 195Pt with other nuclei 2 3 Nucleus 1J Hz 2J Hz 3J Hz 4J Hz 1H gt 700 30 to 70 15 to 50 9 to 1613C 500 to 1800 10 to 55 10 to 40 12 to 1515N 150 to 35031P 1500 to 6000119Sn gt 20000Coupling of 195Pt to 1H 13C 31P 19F or 15N has been reported through one up to four bonds 1J to 4J and is commonly studied to provide additional structural information for platinum complexes 2 3 The 34 abundance of 195Pt with the remaining 66 of natural Pt being NMR inactive means that this coupling appears in the respective 1H 31P 15N 13C NMR spectra as satellite peaks cf 13C satellites which for example result in 17 66 17 patterns for singlets 3 The trans influence in 16 e square planar PtII complexes has been studied by comparing the magnitude of coupling constants in the cis and trans isomers 2 3 Complicated homonuclear couplings ranging from 60 to 9000 Hz for 1J 195Pt 195Pt are of interest in the context of platinum cluster compounds 3 References Edit a b c d e f g Appleton Trevor G 2017 01 01 NMR Spectroscopy Heteronuclei La Hg in Lindon John C Tranter George E Koppenaal David W eds Encyclopedia of Spectroscopy and Spectrometry Third Edition Oxford Academic Press pp 342 345 ISBN 978 0 12 803224 4 retrieved 2021 03 23 a b c d e f g h i j k l m Still Brett M Kumar P G Anil Aldrich Wright Janice R Price William S 2007 03 27 195Pt NMR theory and application Chemical Society Reviews 36 4 665 686 doi 10 1039 B606190G ISSN 1460 4744 PMID 17387413 a b c d e f g h i j k l m n Priqueler Julien R L Butler Ian S Rochon Fernande D 2006 07 01 An Overview of 195Pt Nuclear Magnetic Resonance Spectroscopy Applied Spectroscopy Reviews 41 3 185 226 Bibcode 2006ApSRv 41 185P doi 10 1080 05704920600620311 ISSN 0570 4928 S2CID 94037740 Retrieved from https en wikipedia org w index php title Platinum 195 nuclear magnetic resonance amp oldid 1154408862, wikipedia, wiki, book, books, library,
