OH Stretching Frequency Shifts Research Articles

Hydrogen bonding. Part III: The proton acceptor ability of S = O groups: Sulfinic esters and sulfinyl chlorides as hydrogen bond acceptors

AbstractIntermolecular hydrogen bonding between phenol and a series of sulfinic esters and sulfinyl chlorides has been studied by IR spectroscopy. The magnitudes of the OH stretching frequency shifts, Δν, indicate that inductive effects of substituents attached to the sulfur atom predominate over resonance effects in determining the sulfur‐oxygen bond polarity.The Δν values of nine different types of sulfinyl, XS(O)Y, and sulfonyl, XSO2Y, compounds (X and/or Y are CH3, CH3O, Cl) are compared and interpreted in terms of the ground state electron availibility on the oxygen atom of the SO acceptor site. The preparation of the first representative of an aryl alkanesulfinate, CH3S(O)OC6H5, is described.

Hydrogen bonding properties of α‐Diazosulfones and α‐Diazoketones

AbstractIR and NMR spectral evidence indicates that α‐diazosulfones, RSO2CHN2 (I), and α‐diazoketones, RCOCHN2 (II), donate and accept protons in hydrogen bonding. The proton donor properties involve the methine proton as the donor site. The proton acceptor site is the sulfonyl group for α‐diazosulfones and the carbonyl moiety for α‐diazoketones. Using phenol as a donor molecule, OH stretching frequency shifts, Δν, have been measured for the α‐diazosulfones Ia‐Ig and the α‐diazoketones IIa‐IIf. Substituent effects on Δν values are modest for Ia‐Ig but more pronounced for IIa‐IIf. Compared with α‐diazoketones, α‐diazosulfones are stronger proton donors but weaker proton acceptors in hydrogen bonding.

C‐nitroso compounds. Part X: C‐nitroso compounds as hydrogen bond acceptors

AbstractIntermolecular hydrogen bonding between phenol and a series of monomeric and trans‐dimeric C‐nitroso compounds has been studied by IR and PMR spectroscopy.The rather small OH stretching frequency shifts Δv for monomeric C‐nitroso compounds indicate a weak “ground state” basicity for the NO group. For five p‐substituted nitrosobenzenes Δv values are correlated by σ+ substituent constants. Trans‐dimeric C‐nitroso compounds form stronger hydrogen bonds than the corresponding monomers, resulting in a shift of the monomer‐trans‐‐dimer equilibrium upon addition of a proton donor like phenol.