Maria M. Ilczyszyn

Classification and nature of hydrogen bonds to betaine. X-ray, 13C CP MAS and IR description of low barrier hydrogen bonds

Abstract Twenty two crystalline complexes of betaine [(CH 3 ) 3 N + –CH 2 –COO − ] with different acids are considered. The resulting hydrogen bonds to the betaine oxygen atoms are characterised by X-ray, 13 C NMR and IR data. On this basis five categories of the betaine–acid complexes and their hydrogen bonds are described: (1) MO — the molecular complexes with the bonding protons do not transferre to the betaine; (2) IP — the hydrogen bonded ion pairs with the bonding proton at the betaine oxygen atom, (3) BHB — the homoconjugated betaine complexes with the bonding proton at the central region of the hydrogen bonds, (4) PPD — the MO, IP and BHB complexes with the bonding proton position disorder and (5) LBHB — the PPD complexes with low barrier hydrogen bonds. The results indicate conditions and possible inversion mechanisms of the bonding proton positions. For the betaine phosphoric acid complex the proton disorder, inside one of its hydrogen bonds, was confirmed.

Structure and IR spectra of the solid complex of bis (betaine)—telluric acid

Abstract Crystals of bis (betaine)-telluric acid of the formula [(CH 3 ) 3 NCH 2 CO 2 ] 2 · Te(OH) 6 are triclinic, space group P - 1, with a = 7.164(5), b = 8.325(5), c = 10.035(6) A, α = 108.58(5), β = 123.82(4), γ = 96.02(5)° and Z =1. The crystal structure, solved by the heavy atom method, has been refined to R = 0.0215 for 3887 non-zero reflections. The betaine molecules are linked to telluric acid molecules by three kinds of O⋯O hydrogen bonds of length 2.561(4) A, 2.760(3) A and 2.800 (3) A, respectively. Both species are joined into infinite chains along the a direction. Powder FT-IR spectra of the title crystal and its deuterated analogue at differential temperatures have been taken. The broad band at 3116 cm −1 is assigned to the stretching vibrations of the long hydrogen bonds. The two bands at 2671 and 2443 cm −1 are attributed to the stretching vibration of the short hydrogen bond. The internal vibrations of both the tellurate ions and betaine molecules are discussed. An assignment of the bands arising from these vibrations is proposed.

Structure and vibrational spectra of the solid complex of betaine-sulphuric acid monohydrate

Abstract The crystal structure of betaine-sulphuric acid monohydrate has been determined by X-ray diffraction as a monoclinic species of space group P2 1 a , with a = 14.108(1) A , b = 11.702(2) A , c = 6.520(3) A , β = 101.00(3) and Z = 4. The crystal comprises hydrogen-bonded units containing two bisulphate ions and two water molecules linked in a ring, with a protonated betaine molecule attached to each of the bisulphate ions. Neighbouring units are linked by a hydrogen bond between a bisulphate ion and a water molecule. Powder FT-IR and Raman spectra were measured, and an assignment of the observed bands to vibrations of the hydrogen bonds and internal vibrations of the bisulphate ion and the betaine molecules is proposed. No evidence was found for any spectral changes in the vicinity of the phase transition previously reported at 253.7 K.

Structure and polarized infrared and Raman spectra of the solid complex of betaine and maleic acid (1:1)

Abstract Crystals of betaine maleic acid (BHM) of the formula [(CH3)3N+CH2COOH]·[HCOOCHCHCOO−] are monoclinic, space group P 1 n , with a = 6.138(3), b = 10.831(4), c = 17.244(5) A , β = 92.85(4)° and Z = 4. The betaine cation is linked to the maleic monoanion by a strong intermolecular O ⋯ O hydrogen bond of length 2.527(3) A forming a “structure unit”. The hydrogen maleate anion forms a ring structure containing a short, very asymmetric intramolecular hydrogen bond: O ⋯ O = 2.429(3), OH = 1.04(4), H ⋯ O = 1.39(4) A . The polarized infrared and Raman spectra of the BHM single crystal have been measured at room temperature. The hydrogen bond modes and the internal vibrations of the maleate anion and betaine cation are discussed in relation to the crystal structure. A broad absorption was observed due to the antisymmetric stretching mode of both short hydrogen bonds, but it could not distinguish features pertaining to the intramolecular and intermolecular hydrogen bonds, respectively.

Sarcosine-maleic acid (1:1) crystal: structure, 13C NMR and vibrational properties, protonation character

The crystal structure of sarcosine-maleic acid (1:1) complex has been determined by X-ray diffraction method at 293 K as monoclinic, space group C2/c, Z=8. The crystal unit consists of semi-maleate and sarcosinium ions with two strong hydrogen bonds: the intramolecular one in the maleic part of the complex and the intermolecular one between sarcosinium and semi-maleate carboxylic groups. Phase transitions in this crystal are excluded. Its structure is in accordance with FT-IR, FT-Raman and 13C NMR study. Properties of the titled crystal and a family of similar amino acid-maleic acid systems are compared and discussed. Special attention is paid for relations between different structural and spectroscopic parameters as well as for character of hydrogen bonds formed in these crystalline complexes.

Polarised FTIR and Raman spectra of betaine phosphite single crystal I. Paraelectric phase

Abstract Polarised IR and Raman spectra of the betaine phosphite (BPI = Betaine-H 3 PO 3 ) single crystals were measured at room temperature (paraelectric phase). The assignment of the bands is proposed on the basis of the oriented gas model approximation. The stretching vibrations ( v OH) of the hydrogen bonds give strong absorption extending from ca. 3000 cm −1 to 500 cm −1 in the IR spectra polarised parallel to the ferroelectric b(Z) axis (0(4)H(13)...0(4′) (PP2) hydrogen bond) and parallel to the X axis (0(2)H(12)...0(3) (BP) and 0(6)H(15)...0(6′) (PP1)) hydrogen bonds). Those absorptions show characteristic ABC structure with quite weak the A bands. The C bands (ca. 1600 cm − ) correspond to the fundamental νOH vibrations. The stretching vibrations of the PO bonds in the phosphite anions show unusual properties which may be explained either by strong coupling with the vibrations (stretching v OH and out-of-plane bending γOH) of the hydrogen bonds or by the disorder of the protons in the inter-phosphite (PP1 and PP2) hydrogen bonds. The betaine molecules are in the form of cations ((CH 3 ) 3 N + CH 2 COOH). Some internal vibrations ( v C=O, v s C 3 N) strongly interact with the stretching vibrations of the hydrogen bonds. Broad scattering (the broad wing of the Rayleigh line) is observed in the Raman spectrum X(zz)Y below 200 cm −1 . It originates either from a low wavenumber overdamped mode or from the disordering in the paraelectric phase.

Polarized infrared spectra of potassium hydrogen maleate and potassium deuterium maleate single crystals

Abstract The polarized infrared spectra of single crystals for potassium hydrogen maleate (KHM) and its deuterated analogue (KDM) have been measured at room and low (approximately 15 K) temperature. The hydrogen bond and internal vibrations of the maleate ion are discussed. The antisymmetric stretching vibration, ν a OHO, of the strong hydrogen bond gives rise to an intense, broad absorption with its centre of gravity at approximately 820(±50)cm −1 , divided into three broad bands at 990, 700 and 545 cm −1 by wide ‘transmission windows’ (at 795 and 605 cm −1 ). These transmission windows result from the strong anharmonic interaction of ν a OHO with some of the internal modes of the maleate anion. Deuteration results in a surprisingly small change in the ν a OHO absorption. The γOHO vibration obeys C s site symmetry selection rules; thus the hydrogen-bond potential in the KHM crystal is symmetrical with a single minimum. The possibility of coupling between the νCO and νCO vibrations is considered.

β-Alanine–hydrochloride (2:1) crystal: structure, 13C NMR and vibrational properties, protonation character

The crystal structure of beta-alanine-hydrochloride (2:1) complex (2A-HCl) has been determined by X-ray diffraction method at 298 and 100 K as monoclinic, space group C2/c, Z=4. The crystal comprises chloride anions and protonated beta-alanine dimers: two beta-alanine zwitterions are joined by strong, symmetric (Ci) hydrogen bond with the O...O distance of 2.473 A at room temperature. Powder FT-IR and FT-Raman as well as solid state 13C NMR spectra provide insights into the solid structure of this complex, character of its hydrogen bonds and the beta-alanine protonation.

Polarized vibrational spectra of betaine monohydrate single crystal

Abstract The polarized infrared and Raman spectra of betaine monohydrate single crystal were measured and discussed in relation to the crystal structure. An assignment of the observed bands to the internal vibrations of the betaine and water molecules is proposed.

Infrared and raman spectra of crystalline quinuclidin-3-one hemiperchlorate with symmetrical NHN hydrogen bonds

Abstract Infrared and Raman studies have been performed on polycrystalline and monocrystalline samples of quinuclidin-3-one hemipercholate which at low temperature contain symmetric [NHN] + hydrogen bonds. The most characteristic feature of the IR spectrum is a continuous broad absorption polarized parallel to the hydrogen bond direction. The Evans holes in the low-frequency range are most probably due to the coupling of protonic vibrations with internal modes of quinuclidine moieties leading to a modulation of the bridge geometry. Unusual isotopic and temperature effects could indicate a particular shape of the potential for the proton motion.