Table 2.

The frequencies of O-H⋯O groups for some compounds developed in IR spectra the OH stretching as a broad absorption with A, B and C contours.

Type of O-H⋯O group	Compound	Method	Stretching vibration			Bending vibration		RO⋯O, Å	Ref
			A	B	C	δ(OHO)	γ(OHO)
(C)O-H⋯O(X)	H-complexes of carboxylic acids	IR	2800	2500	1900	1200–1600	900–1100		36–38
(O3P)O-H⋯O(PO3)	K2HPO4·3H2O	IR	2700	2330 2265	1670 1700	1220 1212	800	2.578	39
(O3P)O-H⋯O(PO3)	Ca(H2PO4)2·H2O	IR	2920	2375	1700	*	*	2.596	40
(S)O-H⋯O(S)	CsHSO4	IR, Raman	2850	2500	1680	1252	884	2.572	41
(Se)O-H⋯O(Se)	CsHSeO4	IR, Raman	2840	2415	1600	1258	805	2.603	42
(Se)O-H⋯O(Se)	C6H5SeOOH	IR	2740	2270	1650	*	*	2.52	43
(P)O-H⋯O(P)	dialkylphosphoric and dialkylphosphinic acids	IR44,45	2600–2800	2200–2400	1610–1700	*	*	2.5346 2.5147