TY - JOUR

T1 - H/D isotope effects on 1H-NMR chemical shifts in cyclic heterodimers and heterotrimers of phosphinic and phosphoric acids

AU - Mulloyarova, Valeriia V.

AU - Ustimchuk, Daria O.

AU - Filarowski, Aleksander

AU - Tolstoy, Peter M.

PY - 2020/4/2

Y1 - 2020/4/2

N2 - Hydrogen-bonded heterocomplexes formed by POOH-containing acids (diphenylphosphoric 1, dimethylphosphoric 2, diphenylphosphinic 3, and dimethylphosphinic 4) are studied by the low-temperature (100 K) 1H-NMR and 31P-NMR using liquefied gases CDF3/CDF2Cl as a solvent. Formation of cyclic dimers and cyclic trimers consisting of molecules of two different acids is confirmed by the analysis of vicinal H/D isotope effects (changes in the bridging proton chemical shift, δH, after the deuteration of a neighboring H-bond). Acids 1 and 4 (or 1 and 3) form heterotrimers with very strong (short) H-bonds (δH ca. 17 ppm). While in the case of all heterotrimers the H-bonds are cyclically arranged head-to-tail, ···O=P–O–H···O=P–O–H···, and thus their cooperative coupling is expected, the signs of vicinal H/D isotope effects indicate an effective anticooperativity, presumably due to steric factors: when one of the H-bonds is elongated upon deuteration, the structure of the heterotrimer adjusts by shortening the neighboring hydrogen bonds. We also demonstrate the formation of cyclic tetramers: in the case of acids 1 and 4 the structure has alternating molecules of 1 and 4 in the cycle, while in case of acids 1 and 3 the cycle has two molecules of 1 followed by two molecules of 3.

AB - Hydrogen-bonded heterocomplexes formed by POOH-containing acids (diphenylphosphoric 1, dimethylphosphoric 2, diphenylphosphinic 3, and dimethylphosphinic 4) are studied by the low-temperature (100 K) 1H-NMR and 31P-NMR using liquefied gases CDF3/CDF2Cl as a solvent. Formation of cyclic dimers and cyclic trimers consisting of molecules of two different acids is confirmed by the analysis of vicinal H/D isotope effects (changes in the bridging proton chemical shift, δH, after the deuteration of a neighboring H-bond). Acids 1 and 4 (or 1 and 3) form heterotrimers with very strong (short) H-bonds (δH ca. 17 ppm). While in the case of all heterotrimers the H-bonds are cyclically arranged head-to-tail, ···O=P–O–H···O=P–O–H···, and thus their cooperative coupling is expected, the signs of vicinal H/D isotope effects indicate an effective anticooperativity, presumably due to steric factors: when one of the H-bonds is elongated upon deuteration, the structure of the heterotrimer adjusts by shortening the neighboring hydrogen bonds. We also demonstrate the formation of cyclic tetramers: in the case of acids 1 and 4 the structure has alternating molecules of 1 and 4 in the cycle, while in case of acids 1 and 3 the cycle has two molecules of 1 followed by two molecules of 3.

KW - H/D isotope effects

KW - Heterodimers

KW - Heterotetramers

KW - Heterotrimers

KW - Hydrogen bond

KW - NMR

KW - Phosphinic acids

KW - Phosphoric acids

KW - heterotrimers

KW - HYDROGEN-BOND

KW - heterotetramers

KW - CRYSTAL-STRUCTURE

KW - PHASE ELECTRON-DIFFRACTION

KW - PROTON

KW - heterodimers

KW - DIMERS

KW - ACETIC-ACID

KW - phosphinic acids

KW - SOLVENT

KW - phosphoric acids

KW - GAS-PHASE

KW - hydrogen bond

KW - CARBOXYLIC-ACIDS

UR - http://www.scopus.com/inward/record.url?scp=85083557255&partnerID=8YFLogxK

UR - https://www.mendeley.com/catalogue/daae739a-ac8e-3a13-b73c-4bac235099e9/

U2 - 10.3390/molecules25081907

DO - 10.3390/molecules25081907

M3 - Article

C2 - 32326122

AN - SCOPUS:85083557255

VL - 25

JO - Molecules

JF - Molecules

SN - 1420-3049

IS - 8

M1 - 1907

ER -