Do corresponding coupling constants in hydrogen-bonded homo- and hetero-chiral dimers differ?

Abstract

Ab initio equation-of-motion coupled cluster singles and doubles (EOM-CCSD) calculations have been carried out to evaluate spin-spin coupling constants in six pairs of homo-and hetero-chiral dimers: (HOOH) 2 , (H 2 NNH 2 ) 2 , (FOOH) 2 , (FHNNH 2 ) 2 , (HOOOH) 2 , and (FOOOH) 2 . Corresponding spin-spin coupling constants in these isomeric pairs of C2 and Ci symmetry may differ, but these differences are small and may not be detectable experimentally. For the complexes with O1-HÁÁÁO and O1-HÁÁÁF hydrogen bonds, 1 J(O1-H) has a larger absolute value in the C2 isomer. For the same set of complexes, 1 J(O1-O2) has a larger absolute value in the Ci isomer. No distinguishable patterns could be discerned in the remaining spin-spin coupling constants in the C2 and Ci isomers of these complexes, nor in complexes with N-HÁÁÁN hydrogen bonds. Résumé: Des calculs ab initio EOM-CCSD ont été effectués pour évaluer les constantes de couplage spin-spin dans six paires de dimères homo-et heterochiral : (HOOH)2, (H2NNH2)2, (FOOH)2, (FHNNH2)2, (HOOOH)2, et (FOOOH)2. Les correspondantes constantes de couplage spin-spin dans les paires d'isomères sont, en général, différentes mais les différen-ces sont faibles au point, pour certaines d'entre elles, de ne pas pouvoir être détectées expérimentalement. Pour les complexes avec des liaisons hydrogène O-HÁÁÁO et O-HÁÁÁF, 1 J(O1-H) a une plus large valeur absolue dans l'isomère C2. Pour le même ensemble des complexes, 1 J(O1-O2) a une plus large valeur absolue dans l'isomère Ci. On ne trouve pas des rè-gles générales pour les restantes constantes de couplage spin-spin dans les isomères C2 et Ci de ces complexes et non plus dans les complexes avec des liaisons hydrogène N-HÁÁÁN. Mots-clés : constantes de couplage spin-spin, homo-et hetero-chiral dimères, liaisons hydrogène.

Recent Advances in the Chemistry of Hydrogen Trioxide (HOOOH)

“…The stronger binding interaction in the HOOOH cyclic dimer ( 2A , BE = 8.35 kcal/mol, B3LYP) as compared to that in the analogous structure of the HOOH dimer (BE = 7.31 kcal/mol), indicates that hydrogen trioxide is a stronger proton donor (stronger acid) than hydrogen peroxide . A recent theoretical study [MP2/6-311++G(d,p)] indicates that homo- and heterochiral dimers of HOOOH (of C 2 and C i symmetry) differ somewhat in binding energy, but the differences appear to be too small for allowing experimental distinction …”

“…87a A recent theoretical study [MP2/6-311++G(d,p)] indicates that homoand heterochiral dimers of HOOOH (of C 2 and C i symmetry) differ somewhat in binding energy, but the differences appear to be too small for allowing experimental distinction. 96 The binding energies per unit monomer in the trimers are greater than those in the dimers. 87 Thus, there is a slight favorable cooperative effect in forming the long-chain structures.…”

Theoretical Study of the 1:1 and 2:1 (Homo- and Heterochiral) Complexes of XOOX′ (X, X′ = H, CH3) with Lithium Cation

“…Hydrogen peroxide and its derivatives have been widely used as models to computationally study chiral properties due to their small size, which makes them very adequate for theoretical studies. Thus, their optical rotatory power (ORP) shows a very interesting dependence on the dihedral angle, providing both positive and negative values in the range 0–180°. , The atomic partition of the ORP has been carried out using the acceleration gauge for the electric dipole and the torque formalisms. , The chiral discrimination of the dimers (homochiral vs heterochiral) has been previously studied for several of its derivatives (HOOX, X = H, CCH, CH 3 , CF 3 , t -C 4 H 9 , CN, F, Cl) , and for large clusters of the parent compound. , The coupling constants of some dimers have been calculated to check the possibility of this property to distinguish between homo- and heterochiral complexes . The inclusion of the solvent effect on the chiral discrimination on the dimers of hydrogen peroxide and its methyl derivatives showed that their relative stability could be reversed due to solvation. , …”

Chiral Discrimination by Vibrational Spectroscopy Utilizing Local Modes

“…If this is done, electronic effects, which overrule H‐bonding, can be easily identified as in the case of the mono‐fluorinated hydrazine dimer 4 for which dipole‐dipole attraction becomes decisive. In passing, we note that Del Bene and coworkers recently tried to base chiral discrimination of homo‐ and heterochiral pairs 1–6 on NMR SSCCs. These authors found that the calculated differences in the SSCCs are too small to be detectable experimentally.…”

“…A recent example is the chiral recognition of of diastereomeric 6‐cedrols by VCD . Recently, Del Bene and coworkers investigated whether NMR spin‐spin coupling constants (SSCCs) may be a tool for chiral discrimination. They found that, in most cases, the values of the spin‐spin coupling constants differ only marginally so that they cannot be used for chiral discrimination.…”