Br NQR Frequency with pkb Value and with the N-H Br Hydrogen Bond in Some Ammonium Bromide Salts

Transcription

1 J. Fac. Edu. Saga Univ. of Br NQR Frequency with pkb Value and with the N-H Br Hydrogen Bond in Some Ammonium Bromide Salts 95 Vol.The 19,Correlation No. 1 (2014) The Correlation of Br NQR Frequency with pkb Value and with the N-H Br Hydrogen Bond in Some Ammonium Bromide Salts Takeharu IWAKIRI, Emiko YAMAKAWA, Masashi NODA, Michio NAKASHIMA, Hideta ISHIHARA Summary Br NQR of guanidinium bromide C(NH2)3Br(Ⅰ), hydrazinium bromide N2H5Br(Ⅱ), phenylenediammonium bromide H3NC6H5NH3Br2 (Ⅲ), and diphenylammonium bromide (C6H5)2NH2 Br (Ⅳ) are observed and these frequencies are well correlated with pkb values of original amines. This tendency could be explained by the strength of N-H Br hydrogen bonds. The crystal structure of (Ⅰ) is orthorhombic (Pnma, Z = 4, a = 866.2(1), b = 680.9(1), and c = 833.3(1) pm). The crystal structure of (Ⅲ) is triclinic (P1 with Z = 1, a = 610.5(2), b = 872.4(2), c = 448.6(2) pm, a = (2), b = (3), g = 70.23(2) ). The observed distances of N-H Br hydrogen bonds in (Ⅰ) and (Ⅲ) are also correlated with Br NQR frequencies. The results of EFG calculation of Br atoms in the giant molecules of (Ⅰ) and (Ⅲ) cut off from each crystal structure could reproduce the difference of NQR frequency between (Ⅰ) and (Ⅲ). The temperature dependence of Br NQR frequencies of (Ⅱ)- (Ⅳ) showed normal feature which could be explained by lattice vibration (Bayer theory), but no unique feature caused by hydrogen bond. Key words : Crystal Structure, Hydrogen Bond, Br NQR, Dissociation Constant Introduction Sugimoto et al. showed that the strength of the In solution, the ability of the proton transfer of hydrogen bonding increased as the pkb value of acid is discussed often on the basis of the anions decreased in the series of triprotonated tris dissociation constant pka. In the case of amine, ( 2-pyridylmethyl ) amine, H3TPA3+ [1]. They this constant refers to the conjugate acid, or the used ammonium cation. The pka dissociation constant voltammogram (CV) to estimate the strength of corresponds to the acidity of the ammonium the hydrogen bonds. X-ray, IR, 1H-NMR, and cyclic cation ( conjugate acid ), and conversely to the The nuclear quadrupole resonance (NQR) basicity of the amine molecule ( original base ) ; spectroscopy is an experimental technique which pka + pkb = pkw, where Kw is the ionization is very useful to elucidate the electronic constant of water. distributions around the relevant nucleus in the Faculty of Culture and Education, Saga University, Saga , Japan Reprint requests to Prof. H. I. isiharah@cc.saga-u.ac.jp

2 96 Takeharu IWAKIRI, Emiko YAMAKAWA, Masashi NODA, Michio NAKASHIMA, Hideta ISHIHARA crystalline solids and has thus been intensively NC6H5NH3Br2 ( Ⅲ ), and diphenylammonium used in studying of chemical bonding, crystal bromide (C6H5)2NH2Br (Ⅳ) are listed in Table 1 structures, and phase transitions, etc. Therefore, with the result of 4-Cl-C6H4NH3Br [6]. NQR can also give a good measure to estimate the strength of hydrogen bonds. The temperature dependences of Br or 79 Br NQR frequencies of (Ⅱ)-(Ⅳ) are shown in Fig. 1 Borchers and Weiss suggested that the and 2 and unique features, which was supposed to strength of the hydrogen bond N-H Cl in A2 be due to the effect of hydrogen bond, did not [ SnCl6 ] and A ʼ [ SnCl6 ] series increases with appear. Figure 3 shows the correlation between the increasing pkb of organic base [2], according to the results of 35 Cl NQR measurements. Br NQR frequency of (Ⅱ)-(Ⅳ) at 77 K except for ( Ⅰ ) at 298 K and pkb values of original amines with reported frequencies [ R1-R10 ]. In the case of diacidic base, the smaller value of pkb is used to plot the figure. This figure suggests the We have investigate applied the the halogen hydrogen NQR transfer to strong correlation between NQR frequencies and of pkb values as suggested above. intermolecular H-bonds in solids by measuring temperature dependencies of the 35 The crystal structure determination was Cl NQR carried out to confirm the existence of hydrogen relaxation in a series of the complex compounds of bond. Experimental conditions for the crystal diazines [3-5], revealing that the intermolecular structure determination and crystallographic data H-transfer can be observed by the NQR of C(NH2)3Br (Ⅰ) and H3NC6H5NH3Br2 (Ⅲ) are technique. listed in Table 2. The atomic coordinates are listed In solid ammonium bromide salts, proton in Table 3. Bond lengths, bond angles and short transfer from HBr to base is influenced by contacts are listed in Table 4. The crystal strength of base, or pkb. The complete proton structures of (Ⅰ) and (Ⅲ) are shown in Fig. 4 - transfer to base leads to form a symmetrical Br and 5. In comparison of the Br N and Br H ion and the electric field gradient at Br site distances of (Ⅰ) with (Ⅲ), the distances of (Ⅰ) becomes zero and then Br NQR is not observed. are longer than ( III ) and it is obvious that the Therefore the NQR frequency of Br gives a strength of N-H bond in (Ⅰ) is larger than (Ⅲ) measure to estimate the strength of the hydrogen which can be guessed according to the pkb value bonds. as seen in Table 1. The data of crystal structure of 4-Cl-C6 H4 NH3 Br [ 7 ] and NH2 NH3 Br [ 8 ] are listed together for comparison. Figure 6 shows the result of IR measurement of (Ⅲ) with IR spectra of original diamine. The N-H deformation vibration at 1625 cm-1 and C-N Results and discussion Br NQR frequencies of guanidinium are moved to 1570 cm-1 and 1490 cm-1, and to 1320 bromide C(NH2 )3 Br (Ⅰ), hydrazinium bromide cm-1 of (Ⅲ), respectively. This observation N2H5Br (Ⅱ), phenylenediammonium bromide H3 shows the formation of NH3+ group from NH2 The stretching vibration at 1270 cm-1 of original amine

3 The Correlation of Br NQR Frequency with pkb Value and with the N-H Br Hydrogen Bond in Some Ammonium Bromide Salts 97 Table 1. Br NQR frequencies at 77 K and pkb values Compounds (Ⅰ) (Ⅱ) (Ⅲ) nobs(br)(mhz) Av. of n 8.00 pkb a) NH Br (pm) 262 N Br (pm) 349 (Ⅳ) Cl-C6H4NH3Br [6] [7] 334 [8] ncal(br)(mhz) hcal a) Frequency at 298 K The averaged value Fig. 1. Temperature dependence of Br NQR frequency of (Ⅱ). The solid line shows the fitting curve by least-squares method (Appendix I). Fig. 2. Temperature dependence of 79Br NQR frequency of (Ⅳ)(upper part) and (Ⅲ)(lower part). The solid line shows the fitting curve by least-squares method (Appendix I). group. effect which leads to about 7 %. The electron Br NQR density on the concerned Br- ion : ( Ⅰ ) , frequency was carried out and the results are ( Ⅲ ) , and 4-Cl-C6 H4 NH3 Br The listed in Table 1. The calculated frequency electron density of (Ⅰ) is the greatest and this estimated from the occupation number of the 4p indicates the lowest valence shell of the Br atom could not reproduce case of 4-Cl-C6H4NH3Br, the calculated Br NQR the observed frequency, but we could obtain the frequency is less affected by the crystal field than listed values in consideration of the crystal field (Ⅲ) : in MHz from MHz without the Molecular orbital calculation of the Br NQR frequency. In the

4 98 Takeharu IWAKIRI, Emiko YAMAKAWA, Masashi NODA, Michio NAKASHIMA, Hideta ISHIHARA 30 Ⅳ 25 R9 n(br)(mhz) 20 R7 R8 Ⅲ R10 R5 15 R4 R3 R6 R2 10 Ⅱ R1 Ⅰ pkb Fig. 3. The relation between Br NQR frequency and pkb. [R1] (CH3)3CNH3Br : M. Shabazi, S. Dou, and Al. Weiss, Z. Naturforsch. 47a, (1992). [R2] CH3NH3Br : J. J. R. Frausto Da Silva, L. F. V. Boas, Rev. Port. Quim. 14(2), (1972). [R3] NH3(CH2)2NH3Br2 : J. Hartmann, S. Dou, and Al. Weiss, Z. Naturforsch. 44a, 41-55(1989). [R4] 4-CH3C6H4NH3Br : V. S. Bai and Al. Weiss, Z. Naturforsch. 39a, (1984). [R5] 4-FC6H4NH3Br : V. G. Krishnan and Al. Weiss, Ber. Bunsenge. Phys. Chem. 87, (1983). [R6] C6H5NH3Br : W. Pies and Al. Weiss, Bull. Chem. Soc. Jpn. 51, (1978). [R7] C6H5N(CH3)H2Br : V. G. Krishnan and Al. Weiss, Ber. Bunsenge. Phys. Chem. 87, (1983). [R8] 4-ClC6H4NH3 Br : J. Hartmann, S. Dou, and Al. Weiss, Ber. Bunsenges. Phys. Chem. 94, (1990). [R9] 2-ClC6H4NH3Br : J. Hartmann and Al. Weiss, Z. Naturforsch. 46a, (1991). [R10] 4-CNC6H4NH3Br : V. G. Krishnan and Al. Weiss, J. Mol. Struct. 111, (1983). crystal field in 4-Cl-C6H4NH3Br, but MHz difference of the strength of N-H Br hydrogen from MHz in (Ⅲ). This means the strength bond. This explanation is supported by the X-ray of H Br bond of 4-Cl-C6H4NH3Br is larger than structure analysis and MO calculation. (Ⅱ), i. e., the electric field gradient due to H Br bond is decisive in 4-Cl-C6H4NH3Br. Experimental Section Sample preparation Conclusion The Br NQR frequencies are correlated with pkb values and this fact can be explained by the Guanidinium hydrazinium bromide bromide C(NH2)3Br(Ⅰ), N2H5Br(Ⅱ), phenylenediammonium bromide H3NC6H5NH3Br2

5 The Correlation of Br NQR Frequency with pkb Value and with the N-H Br Hydrogen Bond in Some Ammonium Bromide Salts 99 Fig. 4. The projection of the crystal structure of (Ⅰ) along c-axis. The thin lines show hydrogen bonds. Thermal ellipsoid ( 50% ) was made by ORTEP-3[9]. Fig. 5. The projection of the crystal structure of (Ⅲ) along a-axis. The thin lines shown hydrogen bonds. Thermal ellipsoid ( 50% ) was made by ORTEP-3[9]. (Ⅲ), and diphenylammonium bromide (C6 H5 )2 calculations NH2Br (Ⅳ) were prepared by mixing amine and CRYSTALSTRUCTURE 3.8 Crystal Structure Analysis hydrobromic acid in the stoichiometric ratio. The Package [10]. were performed using water solution was kept in a desiccator charged with P2O5 to crystallize. NQR measurement Nuclear quadrupole resonance ( NQR ) spectra Crystal structure determination were measured between 8-35 MHz using a The crystal structures were determined using a homemade four circle X-ray diffractometer Rigaku AFC5S super-regenerative oscillator made of 6C4 tubes (MoKa with Zeeman magnetic modulation and recorded radiation, l = Å, graphite Dean-type external-quenching monochromator, attenuator Zr foil, w/2q scans). through a lock-in amplifier. The The positions of hydrogen atoms were calculated observed were identified by observing the with standard bond lengths and angles. All corresponding 79 Br NQR lines Br lines of the known frequency

6 100 Takeharu IWAKIRI, Emiko YAMAKAWA, Masashi NODA, Michio NAKASHIMA, Hideta ISHIHARA Fig. 6. IR spectra of (Ⅲ) and 4-H2NC6H4NH2. ratio. due to point charge estimated from MO calculation. The principal values of the EFG MO calculation tensor and the asymmetric parameters were MO calculation on PM3 basis was carried out by obtained by diagonalization of eqij including 7.5 % Win GAMESS, a general ab initio quantum of crystal filed effect in each case. For support of chemistry package [11]. The Muliken population MO calculation, WINMOSTAR and MERCURY were analysis of the 4p orbitals of two bromine atoms, used [12]. which symmetrically located at the center of the assumed molecules of (Ⅰ) [(C(NH2)3)10Br6]4+, 8- [(4-ClC6 H5 NH3 )6 Br14 ], and (Ⅲ) [(H3 NC6 H4 6- IR (Infrared spectroscopy) measurements HITACHI Infrared spectrometer was used cut off from the each crystal to observe IR spectra. Sample is mixed with nujol structure, was performed in order to obtain the in a mortar to make a mull and is placed between number of unbalanced p-electron (Up ) and then sodium chloride plates. NH3)8Br22] the components of the electric field gradient (EFG) tensor, eqij (i, j = x, y, z). The crystal field effect was considered by calculating electric field

7 The Correlation of Br NQR Frequency with pkb Value and with the N-H Br Hydrogen Bond in Some Ammonium Bromide Salts 101 Table 2. Experimental conditions for the crystal structure determinations and crystallographic data of C (NH2)3Br (Ⅰ) and H3NC6H4NH3Br2 (Ⅲ), Rigaku AFC5S ; w-2q Scan, wavelength pm (MoKa), monochromator : graphite, Attenuator Zr foil. (Ⅰ) M = , (Ⅲ) M = (Ⅰ) (Ⅲ) Absorption coeff./(cm-1) q-range for data collected 3.0 q/ q/ 27.5 Index ranges 0 h 11, 0 k 8, 0 l 10 0 h 7, -10 k 11, -5 l 5 Space group Pnma P1 a/pm 866.2(1) 610.5(2) b/pm 680.9(1) 872.4(2) c/pm 833.3(1) 448.6(2) a/ (2) b/ (3) g/ (2) V 10-6/(pm3) 491.5(1) 216.0(1) Formula units Z 4 1 rcal/(mg m-3) F(000) Restraints/parameters 0/33 0/52 Goodness of fit S(obs.) R = 0.043, Rw = R = 0.048, Rw = Largest diff. (peak, hole)/(10-6e(pm3)) 0.80 and and Max. and min. trans and and Br, N(1), C atoms in 4c and N(2) and H atoms in 8d. All atoms in 2i. Crystal size/(mm3) Temperature/K Lattice parameter Independent reflections Data (I 2s(I)) Final R (I 2s(I)) Point positions.

8 102 Takeharu IWAKIRI, Emiko YAMAKAWA, Masashi NODA, Michio NAKASHIMA, Hideta ISHIHARA Table 3. Atomic coordinates and equivalent isotropic displacement parameters Beq for (Ⅰ) and (Ⅲ). Beq is defined as the following equation by the anisotropic displacement parameters Uij. The anisotropic displacement parameters Uij, and atomic coordinates for hydrogen atoms are given elsewhere [13]. Beq = 8/3p2[(U11(aa*)2 + U22(bb*)2 + U33(cc*)2 + 2U12(aa*bb*)cos p + 2U13(aa*cc*)cos p + 2U23(bb*cc*) cos p] C(NH2)3Br (Ⅰ) x y z Beq/(10-1pm2) Br (1) (1) 4.24(3) N(1) (11) (13) 7.0(3) N(2) (7) (8) (6) 4.71(16) C (11) (10) 3.9(2) H(1) H(2) H(3) x y z Beq/(10-1pm2) Br (1) (1) (2) 2.50(2) N (10) (6) (14) 2.29(14) C(1) (11) (7) (14) 1.72(14) C(2) (11) (8) (16) 2.25(16) C(3) (11) (8) (16) 2.16(16) H(1) H(2) H(3) H(4) H(5) Atom H3NC6H4NH3Br2(Ⅲ) Atom

9 The Correlation of Br NQR Frequency with pkb Value and with the N-H Br Hydrogen Bond in Some Ammonium Bromide Salts 103 Table 4. Bond lengths ( pm ), bond angles ( ), and short contact. The hydrogen atoms have been determined in the least-squares refinements of the structures by fixing the bond lengths (95 pm) of N-H and C-H and bond angles with the atoms involved. C(NH2)3Br (Ⅰ) d/pm Angle/ N(1)-C 132.8(13) N(1)-C-N(2) 120.1(4) N(2)-C 132.0(7) N(2)-C-N(2)# (7) d(n Br)/pm d(h Br)/pm (N-H Br)/ N(1)-H(1) Br N(2)-H(2) Br# N(2)-H(3) Br d/pm Angle/ N-C(1) 146.4(9) N-C(1)-C(2) 118.0(5) C(1)-C(2) 137.8(12) C(1)-C(2)-C(3) 119.1(5) C(2)-C(3) 139.2(10) C(3)-C(1)-C(2)# (6) d(n Br)/pm d(h Br)/pm (N-H Br)/ N-H(1) Br# N-H(2) Br N-H(3) Br# Short contact in (Ⅰ) #1 : x, 0.5-y, z ; #2 : 1.5-x, 0.5+ y, 0.5+ z. H3NC6H4NH3Br2(Ⅲ) #1 : 1-x, -y, 2-z Short contact in (Ⅲ) #2 : 1-z, 1-y, 2-z, #3 : -1+ x, y, z

10 104 Takeharu IWAKIRI, Emiko YAMAKAWA, Masashi NODA, Michio NAKASHIMA, Hideta ISHIHARA References [9] ORTEP-3 for Windows, L. J. Farrugia, J. Appl. Cryst. 45, [1] H. Sugimoto, H. Miyake and H. Tsukube, J. Chem. Soc., Dalton Trans., 2002, [2] D. Borchers and Al. Weiss, Ber. Bunsenges. Phys. Chem., 93, (1989). [ 3 ] T. Nihei, S. Ishimaru, H. Ishida, H. Ishihara, and R. Ikeda, Chem. Phys. Letters, 329, 7-14 (2000). [ 4 ] T. Nihei, S. Ishimaru, H. Ishida, H. Ishihara, and R. Ikeda, Chem. Letters, 2000, [5] R. Ikeda, S. Tkahashi, the late T. Nihei, H. Ishihara, and H. Ishida, Bull. Chem. Soc. Japan, 78, (2005). [ 6 ] J. Hartmann and Al. Weiss, Ber. Bunsenges. Phys. Chem. 94, (1990). [7] M. Zaho, Acta Crystallogr. Sect E, Struct. Rep. Online 68, o2022 (2012). [ 8 ] K. Sakurai and Y. Tomiie, Acta Crystallogr. 5, 289 (1952) (2012). [10] CRYSTALSTRUCTURE 3.8 Crystal Structure Analysis Package, Rigaku and Rigaku Americans ( ). [11] GAMESS Ver.11, M. W. Schmidt, K. K. Baldridge, J. A. Boatz, S. T. Elbert, M. S. Gordon, J. Jensen, S. Koseki, N. Matsunaga, K. A. Nguyen, S. Su, T. L. Windus, M. Dupuis, J. A. Montgomery, J. Comput. Chem. 14, (1993). [12] WINMOSTAR (ED) V4.100, X-ability Co.Ltd. MERCURY 3.3 Windows, the Cambridge Crystallographic Data Centre (CCDC). [13] CCDC for (I) and CCDC for (III) contains the supplementary crystallographic data for this paper. These data can be obtained free of charge from the Cambridge Crystallographic Data Centre via Appendix I. Fitting parameters of n = a + b/t + c T + d T2 and standard deviation by the least squares method. NH2NH3Br (Ⅱ) a (MHz) b (MHz K) n1 (73)a) c (MHz/K) d (MHz/K2) Standard Deviation (MHz) a) The number of data in parenthesis. H3NC6H4NH3Br2 (Ⅲ) a (MHz) b (MHz K) n1 (33)a) c (MHz/K) d (MHz/K2) Standard Deviation (MHz) a) The number of data in parenthesis. (C6H5)2NH2Br (Ⅳ) a (MHz) b (MHz K) c (MHz/K) d (MHz/K2) Standard Deviation (MHz) n1 (51)a) n2 (44)a) a) The number of date in parenthesis.