organic compounds
of 3-mesityl-1-[(pyridin-2-yl)methyl]-3,4,5,6-tetrahydropyrimidin-1-ium bromide monohydrate
aCollege of Chemistry and Chemical engineering, Henan University of Technology, Zhengzhou 450001, People's Republic of China
*Correspondence e-mail: lryang@haut.edu.cn
In the title hydrated salt, C19H24N3+·Br−·H2O, the values of the N—C bond lengths within the tetrahydropyrimidinium ring indicate delocalization of the N=C double bond. In the cation, the dihedral angle formed by the pyridine and benzene rings is 14.97 (12)°. In the crystal, ions and water molecules are linked by O—H⋯Br, O—H⋯N, C—H⋯Br and C—H⋯O hydrogen bonds into chains running parallel to the b axis.
CCDC reference: 1051286
1. Related literature
For background on the synthesis and properties of N-heterocyclic see: Hopkinson et al. (2014); Mata et al. (2007); Dunsford & Cavell (2014); Mao et al. (2012).
2. Experimental
2.1. Crystal data
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2.3. Refinement
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Data collection: CrysAlis PRO (Agilent, 2011); cell CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2.
Supporting information
CCDC reference: 1051286
10.1107/S2056989015003989/rz5148sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S2056989015003989/rz5148Isup2.hkl
Supporting information file. DOI: 10.1107/S2056989015003989/rz5148Isup3.cml
A methanol solution (30 ml) of N-mesitylpropane-1,3-diamine (15 mmol, 2.88 g) was added dropwise to a methanol solution (30 ml) of pyridine-2-formaldehyde (15 mmol, 1.61 g) and the mixture was stirred at room temperature for 5 h. Infrared detection showed the disappearance of the carbonyl group. The mixture was then put into an ice-bath, and NaBH4 (120 mmol, 4.54 g) was added portion-wise for 1 h, before being warmed up to room temperature and then heated to 70 °C overnight. The solvent was evaporated and the residue was poured into a mixture of water (20 ml) and CH2Cl2 (20 ml). The resulting suspension liquid was filtered and the filtrate was extracted by CH2Cl2 (10 ml) for 3 times. The combined organic phase was evaporated and the residue obtained was dissolved in methanol (10 ml) for the following reaction directly. The solution was then treated with aqueous HCHO solution (36.5%, 15 mmol). The mixture was stirred at room temperature for 6 h before being evaporated. Purification of the residue by flash
(silica, pentane/CH2Cl2/Et3N = 8/1/0.05, v/v/v) afforded the pure hexahydropyrimidine.Hexahydropyrimidine (5 mmol, 1.48 g) was dissolved in DME (20 ml). NBS (5 mmol, 0.89 g) was added portion-wise and the resulting mixture was stirred at room temperature for 3 h, during which time a white precipitate formed. The precipitate was filtered and washed with DME. Crystallization of the precipitate from CH2Cl2/diethyl ether (1:1 v/v) afforded the title product as colourless crystals.
The water H atoms could be located in a difference Fourier map, but only one of them (H1B) could be refined freely. The second H atom (H1A) was refined using a rigid-body approximation, with O—H constrained to be 0.9 Å, and with Uiso(H) = 1.5 Ueq(O). All other H atoms were placed geometrically and refined as riding, with C—H = 0.93–0.97 Å, and with Uiso(H) = 1.2 Ueq(C).
N-Heterocyclic σ-donor ability and easy modular variability began to attract extensive attention in recent years (Dunsford & Cavell, 2014). It would be of interest to explore whether the introduction of ring expanded NHCs to a chelating framework will result in new chelating complexes displaying novel reactivity and enhanced catalytic activities. To the best of our knowledge, no report on chelating NHC metal complexes has been presented. Following our interest in the development of ring-expanded NHCs based on substituted 1,4,5,6-tetrahydropyrimidine and their metal complexes (Mao et al., 2012), and with the intention of synthesizing chelating ring-expanded NHC metal complexes, we synthesized the chelating NHC precursor, 3-methyl-1-(pyridin-2-ylmethyl)-3,4,5,6-tetrahydropyrimidin-1-ium bromide and determined the structure of its monohydrate derivative. Research on the synthesis of carbene-metal complexes containing this ligand is currently in progress.
(NHCs) have been widely used as ancillary ligands for the preparation of transition-metal based catalysts (Hopkinson et al., 2014). Chelating NHC metal complexes have attracted particular research interest due to their enhanced stability and modular variability (Mata et al., 2007). Most of the reported chelating NHC metal complexes contain NHC ligands based on imidazole-derived five-membered heterocyclic rings. Ring-expanded NHCs based on six-, seven-, or eight-membered heterocyclic rings possessing enhancedThe molecular structure of the title compound is shown in Figure 1. As expected, the values of the bond distances within the pyrimidinyl ring indicate delocalization of the N═C bond that extends from N2 to N3 through C10, resulting in the increased acidity of the proton on C10 and convenient formation of a carbene functionality. In the cation, the benzene and pyridine rings form a dihedral angle of 14.97 (12)°. In the ions and water molecules are linked by O—H···N, O—H···Br, C—H···Br and C—H···O hydrogen bonds (Table 1) forming chains parallel to the b axis.
For background on the synthesis and properties of N-heterocyclic
see: Hopkinson et al. (2014); Mata et al. (2007); Dunsford & Cavell (2014); Mao et al. (2012).Data collection: CrysAlis PRO (Agilent, 2011); cell
CrysAlis PRO (Agilent, 2011); data reduction: CrysAlis PRO (Agilent, 2011); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).Fig. 1. The molecular structure of the title compound showing 50% probability displacement ellipsoids. |
C19H24N3+·Br−·H2O | Dx = 1.341 Mg m−3 |
Mr = 392.34 | Mo Kα radiation, λ = 0.7107 Å |
Orthorhombic, Pbca | Cell parameters from 1997 reflections |
a = 15.5868 (5) Å | θ = 3.5–23.8° |
b = 14.6323 (4) Å | µ = 2.13 mm−1 |
c = 17.0439 (6) Å | T = 291 K |
V = 3887.2 (2) Å3 | Block, colourless |
Z = 8 | 0.3 × 0.28 × 0.26 mm |
F(000) = 1632 |
Agilent Xcalibur (Eos, Gemini) diffractometer | 3969 independent reflections |
Radiation source: Enhance (Mo) X-ray Source | 2522 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.031 |
Detector resolution: 16.2312 pixels mm-1 | θmax = 26.4°, θmin = 3.0° |
ω scans | h = −10→19 |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2011) | k = −17→18 |
Tmin = 0.910, Tmax = 1.000 | l = −12→21 |
10196 measured reflections |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.051 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.134 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.03 | w = 1/[σ2(Fo2) + (0.053P)2 + 3.4187P] where P = (Fo2 + 2Fc2)/3 |
3969 reflections | (Δ/σ)max < 0.001 |
227 parameters | Δρmax = 0.83 e Å−3 |
1 restraint | Δρmin = −0.81 e Å−3 |
C19H24N3+·Br−·H2O | V = 3887.2 (2) Å3 |
Mr = 392.34 | Z = 8 |
Orthorhombic, Pbca | Mo Kα radiation |
a = 15.5868 (5) Å | µ = 2.13 mm−1 |
b = 14.6323 (4) Å | T = 291 K |
c = 17.0439 (6) Å | 0.3 × 0.28 × 0.26 mm |
Agilent Xcalibur (Eos, Gemini) diffractometer | 3969 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Agilent, 2011) | 2522 reflections with I > 2σ(I) |
Tmin = 0.910, Tmax = 1.000 | Rint = 0.031 |
10196 measured reflections |
R[F2 > 2σ(F2)] = 0.051 | 1 restraint |
wR(F2) = 0.134 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.03 | Δρmax = 0.83 e Å−3 |
3969 reflections | Δρmin = −0.81 e Å−3 |
227 parameters |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
Br1 | 0.26231 (3) | 0.64141 (3) | 0.81482 (3) | 0.06536 (19) | |
O1 | 0.3743 (3) | 0.6154 (2) | 0.6526 (2) | 0.0809 (10) | |
H1A | 0.3514 | 0.6282 | 0.6965 | 0.121* | |
H1B | 0.400 (4) | 0.557 (2) | 0.655 (4) | 0.16 (3)* | |
N1 | 0.4370 (2) | 0.4358 (2) | 0.68596 (18) | 0.0522 (8) | |
N2 | 0.25056 (17) | 0.39948 (18) | 0.67358 (16) | 0.0366 (7) | |
N3 | 0.17792 (18) | 0.48218 (18) | 0.57935 (16) | 0.0388 (7) | |
C1 | 0.5213 (3) | 0.4180 (4) | 0.6729 (3) | 0.0662 (12) | |
H1 | 0.5530 | 0.4597 | 0.6437 | 0.079* | |
C2 | 0.5614 (3) | 0.3423 (4) | 0.7005 (3) | 0.0711 (14) | |
H2 | 0.6191 | 0.3325 | 0.6894 | 0.085* | |
C3 | 0.5176 (3) | 0.2814 (4) | 0.7439 (3) | 0.0701 (13) | |
H3 | 0.5445 | 0.2294 | 0.7634 | 0.084* | |
C4 | 0.4320 (2) | 0.2977 (3) | 0.7589 (2) | 0.0543 (10) | |
H4 | 0.4000 | 0.2566 | 0.7885 | 0.065* | |
C5 | 0.3947 (2) | 0.3756 (2) | 0.7295 (2) | 0.0402 (8) | |
C6 | 0.3017 (2) | 0.3970 (2) | 0.7458 (2) | 0.0398 (8) | |
H6A | 0.2783 | 0.3510 | 0.7808 | 0.048* | |
H6B | 0.2977 | 0.4557 | 0.7720 | 0.048* | |
C7 | 0.2405 (2) | 0.3121 (2) | 0.6312 (2) | 0.0515 (10) | |
H7A | 0.2329 | 0.2627 | 0.6686 | 0.062* | |
H7B | 0.2917 | 0.2997 | 0.6007 | 0.062* | |
C8 | 0.1647 (3) | 0.3168 (3) | 0.5782 (3) | 0.0603 (11) | |
H8A | 0.1651 | 0.2641 | 0.5437 | 0.072* | |
H8B | 0.1128 | 0.3141 | 0.6095 | 0.072* | |
C9 | 0.1631 (3) | 0.4013 (2) | 0.5297 (2) | 0.0590 (11) | |
H9A | 0.2072 | 0.3978 | 0.4897 | 0.071* | |
H9B | 0.1080 | 0.4067 | 0.5038 | 0.071* | |
C10 | 0.21877 (19) | 0.4758 (2) | 0.64654 (18) | 0.0331 (7) | |
H10 | 0.2254 | 0.5285 | 0.6765 | 0.040* | |
C11 | 0.1455 (2) | 0.5698 (2) | 0.55251 (19) | 0.0374 (8) | |
C12 | 0.0677 (2) | 0.6013 (3) | 0.5810 (2) | 0.0464 (9) | |
C13 | 0.0378 (2) | 0.6844 (3) | 0.5527 (2) | 0.0513 (10) | |
H13 | −0.0137 | 0.7073 | 0.5718 | 0.062* | |
C14 | 0.0822 (3) | 0.7342 (2) | 0.4968 (2) | 0.0479 (9) | |
C15 | 0.1587 (3) | 0.6994 (2) | 0.4690 (2) | 0.0495 (9) | |
H15 | 0.1887 | 0.7320 | 0.4310 | 0.059* | |
C16 | 0.1922 (2) | 0.6172 (2) | 0.4960 (2) | 0.0417 (8) | |
C17 | 0.0167 (3) | 0.5487 (3) | 0.6414 (3) | 0.0767 (14) | |
H17A | 0.0448 | 0.5527 | 0.6914 | 0.115* | |
H17B | 0.0128 | 0.4858 | 0.6258 | 0.115* | |
H17C | −0.0399 | 0.5742 | 0.6454 | 0.115* | |
C18 | 0.0496 (3) | 0.8260 (3) | 0.4680 (3) | 0.0712 (13) | |
H18A | 0.0345 | 0.8634 | 0.5122 | 0.107* | |
H18B | 0.0000 | 0.8170 | 0.4356 | 0.107* | |
H18C | 0.0937 | 0.8558 | 0.4382 | 0.107* | |
C19 | 0.2774 (3) | 0.5823 (3) | 0.4660 (2) | 0.0587 (11) | |
H19A | 0.2681 | 0.5294 | 0.4337 | 0.088* | |
H19B | 0.3133 | 0.5661 | 0.5096 | 0.088* | |
H19C | 0.3049 | 0.6291 | 0.4356 | 0.088* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.0891 (4) | 0.0542 (3) | 0.0528 (3) | 0.0202 (2) | 0.0064 (2) | −0.0031 (2) |
O1 | 0.092 (3) | 0.062 (2) | 0.089 (3) | −0.0072 (19) | 0.012 (2) | 0.009 (2) |
N1 | 0.0478 (18) | 0.0560 (19) | 0.0527 (19) | −0.0023 (16) | 0.0061 (16) | 0.0012 (17) |
N2 | 0.0404 (15) | 0.0322 (14) | 0.0371 (15) | 0.0037 (12) | 0.0002 (14) | −0.0037 (13) |
N3 | 0.0463 (16) | 0.0359 (15) | 0.0343 (15) | −0.0024 (14) | −0.0022 (13) | −0.0015 (13) |
C1 | 0.059 (3) | 0.084 (3) | 0.056 (3) | −0.010 (3) | 0.012 (2) | −0.005 (2) |
C2 | 0.039 (2) | 0.108 (4) | 0.066 (3) | 0.008 (3) | −0.006 (2) | −0.013 (3) |
C3 | 0.059 (3) | 0.086 (3) | 0.066 (3) | 0.027 (3) | −0.019 (2) | −0.001 (3) |
C4 | 0.054 (2) | 0.060 (2) | 0.049 (2) | 0.012 (2) | −0.0039 (19) | 0.007 (2) |
C5 | 0.0402 (18) | 0.046 (2) | 0.0341 (18) | 0.0022 (17) | −0.0031 (16) | −0.0017 (16) |
C6 | 0.0403 (19) | 0.0441 (19) | 0.0350 (17) | 0.0053 (16) | −0.0008 (16) | 0.0034 (16) |
C7 | 0.058 (2) | 0.036 (2) | 0.060 (2) | 0.0042 (18) | −0.004 (2) | −0.0077 (19) |
C8 | 0.072 (3) | 0.041 (2) | 0.067 (3) | −0.003 (2) | −0.014 (2) | −0.011 (2) |
C9 | 0.080 (3) | 0.050 (2) | 0.047 (2) | −0.008 (2) | −0.016 (2) | −0.0093 (19) |
C10 | 0.0310 (17) | 0.0345 (17) | 0.0338 (17) | −0.0030 (15) | 0.0041 (15) | 0.0003 (15) |
C11 | 0.0417 (19) | 0.0375 (18) | 0.0331 (17) | −0.0023 (16) | −0.0048 (16) | 0.0020 (16) |
C12 | 0.048 (2) | 0.049 (2) | 0.042 (2) | −0.0007 (18) | −0.0003 (18) | 0.0061 (18) |
C13 | 0.048 (2) | 0.057 (2) | 0.050 (2) | 0.008 (2) | −0.0052 (19) | −0.001 (2) |
C14 | 0.063 (2) | 0.042 (2) | 0.0390 (19) | 0.000 (2) | −0.0183 (19) | 0.0036 (17) |
C15 | 0.065 (3) | 0.047 (2) | 0.0355 (18) | −0.012 (2) | −0.0045 (19) | 0.0067 (18) |
C16 | 0.050 (2) | 0.0429 (19) | 0.0322 (18) | −0.0049 (18) | −0.0001 (17) | −0.0010 (16) |
C17 | 0.063 (3) | 0.084 (3) | 0.083 (3) | 0.013 (3) | 0.027 (3) | 0.029 (3) |
C18 | 0.093 (3) | 0.053 (2) | 0.068 (3) | 0.012 (2) | −0.019 (3) | 0.009 (2) |
C19 | 0.061 (2) | 0.063 (2) | 0.052 (2) | −0.005 (2) | 0.015 (2) | 0.002 (2) |
O1—H1A | 0.8501 | C8—H8B | 0.9700 |
O1—H1B | 0.94 (2) | C8—C9 | 1.486 (5) |
N1—C1 | 1.357 (5) | C9—H9A | 0.9700 |
N1—C5 | 1.327 (4) | C9—H9B | 0.9700 |
N2—C6 | 1.467 (4) | C10—H10 | 0.9300 |
N2—C7 | 1.477 (4) | C11—C12 | 1.385 (5) |
N2—C10 | 1.306 (4) | C11—C16 | 1.392 (5) |
N3—C9 | 1.473 (4) | C12—C13 | 1.388 (5) |
N3—C10 | 1.314 (4) | C12—C17 | 1.512 (5) |
N3—C11 | 1.453 (4) | C13—H13 | 0.9300 |
C1—H1 | 0.9300 | C13—C14 | 1.384 (5) |
C1—C2 | 1.356 (7) | C14—C15 | 1.381 (5) |
C2—H2 | 0.9300 | C14—C18 | 1.518 (5) |
C2—C3 | 1.344 (6) | C15—H15 | 0.9300 |
C3—H3 | 0.9300 | C15—C16 | 1.390 (5) |
C3—C4 | 1.380 (6) | C16—C19 | 1.512 (5) |
C4—H4 | 0.9300 | C17—H17A | 0.9600 |
C4—C5 | 1.375 (5) | C17—H17B | 0.9600 |
C5—C6 | 1.510 (5) | C17—H17C | 0.9600 |
C6—H6A | 0.9700 | C18—H18A | 0.9600 |
C6—H6B | 0.9700 | C18—H18B | 0.9600 |
C7—H7A | 0.9700 | C18—H18C | 0.9600 |
C7—H7B | 0.9700 | C19—H19A | 0.9600 |
C7—C8 | 1.489 (5) | C19—H19B | 0.9600 |
C8—H8A | 0.9700 | C19—H19C | 0.9600 |
H1A—O1—H1B | 109.5 | N3—C9—H9B | 109.6 |
C5—N1—C1 | 116.4 (4) | C8—C9—H9A | 109.6 |
C6—N2—C7 | 116.5 (3) | C8—C9—H9B | 109.6 |
C10—N2—C6 | 121.5 (3) | H9A—C9—H9B | 108.1 |
C10—N2—C7 | 121.8 (3) | N2—C10—N3 | 123.5 (3) |
C10—N3—C9 | 121.3 (3) | N2—C10—H10 | 118.2 |
C10—N3—C11 | 120.4 (3) | N3—C10—H10 | 118.2 |
C11—N3—C9 | 118.3 (3) | C12—C11—N3 | 119.2 (3) |
N1—C1—H1 | 118.4 | C12—C11—C16 | 122.3 (3) |
C2—C1—N1 | 123.1 (4) | C16—C11—N3 | 118.4 (3) |
C2—C1—H1 | 118.4 | C11—C12—C13 | 117.6 (3) |
C1—C2—H2 | 120.1 | C11—C12—C17 | 122.0 (3) |
C3—C2—C1 | 119.8 (4) | C13—C12—C17 | 120.4 (3) |
C3—C2—H2 | 120.1 | C12—C13—H13 | 118.9 |
C2—C3—H3 | 120.7 | C14—C13—C12 | 122.2 (4) |
C2—C3—C4 | 118.6 (4) | C14—C13—H13 | 118.9 |
C4—C3—H3 | 120.7 | C13—C14—C18 | 121.4 (4) |
C3—C4—H4 | 120.5 | C15—C14—C13 | 118.2 (3) |
C5—C4—C3 | 119.0 (4) | C15—C14—C18 | 120.3 (4) |
C5—C4—H4 | 120.5 | C14—C15—H15 | 119.0 |
N1—C5—C4 | 123.0 (3) | C14—C15—C16 | 122.1 (3) |
N1—C5—C6 | 116.3 (3) | C16—C15—H15 | 119.0 |
C4—C5—C6 | 120.7 (3) | C11—C16—C19 | 121.7 (3) |
N2—C6—C5 | 111.8 (3) | C15—C16—C11 | 117.6 (3) |
N2—C6—H6A | 109.3 | C15—C16—C19 | 120.8 (3) |
N2—C6—H6B | 109.3 | C12—C17—H17A | 109.5 |
C5—C6—H6A | 109.3 | C12—C17—H17B | 109.5 |
C5—C6—H6B | 109.3 | C12—C17—H17C | 109.5 |
H6A—C6—H6B | 107.9 | H17A—C17—H17B | 109.5 |
N2—C7—H7A | 109.7 | H17A—C17—H17C | 109.5 |
N2—C7—H7B | 109.7 | H17B—C17—H17C | 109.5 |
N2—C7—C8 | 109.9 (3) | C14—C18—H18A | 109.5 |
H7A—C7—H7B | 108.2 | C14—C18—H18B | 109.5 |
C8—C7—H7A | 109.7 | C14—C18—H18C | 109.5 |
C8—C7—H7B | 109.7 | H18A—C18—H18B | 109.5 |
C7—C8—H8A | 109.0 | H18A—C18—H18C | 109.5 |
C7—C8—H8B | 109.0 | H18B—C18—H18C | 109.5 |
H8A—C8—H8B | 107.8 | C16—C19—H19A | 109.5 |
C9—C8—C7 | 112.9 (3) | C16—C19—H19B | 109.5 |
C9—C8—H8A | 109.0 | C16—C19—H19C | 109.5 |
C9—C8—H8B | 109.0 | H19A—C19—H19B | 109.5 |
N3—C9—C8 | 110.3 (3) | H19A—C19—H19C | 109.5 |
N3—C9—H9A | 109.6 | H19B—C19—H19C | 109.5 |
N1—C1—C2—C3 | −1.0 (7) | C9—N3—C11—C12 | 97.5 (4) |
N1—C5—C6—N2 | 62.8 (4) | C9—N3—C11—C16 | −79.5 (4) |
N2—C7—C8—C9 | 48.0 (5) | C10—N2—C6—C5 | −110.9 (3) |
N3—C11—C12—C13 | −178.5 (3) | C10—N2—C7—C8 | −23.0 (5) |
N3—C11—C12—C17 | 2.1 (5) | C10—N3—C9—C8 | 24.2 (5) |
N3—C11—C16—C15 | 177.8 (3) | C10—N3—C11—C12 | −82.0 (4) |
N3—C11—C16—C19 | −3.6 (5) | C10—N3—C11—C16 | 101.0 (4) |
C1—N1—C5—C4 | −1.5 (5) | C11—N3—C9—C8 | −155.3 (3) |
C1—N1—C5—C6 | 178.3 (3) | C11—N3—C10—N2 | −179.0 (3) |
C1—C2—C3—C4 | 0.4 (7) | C11—C12—C13—C14 | 1.2 (5) |
C2—C3—C4—C5 | −0.4 (6) | C12—C11—C16—C15 | 0.9 (5) |
C3—C4—C5—N1 | 1.0 (6) | C12—C11—C16—C19 | 179.5 (3) |
C3—C4—C5—C6 | −178.8 (4) | C12—C13—C14—C15 | −0.1 (5) |
C4—C5—C6—N2 | −117.3 (4) | C12—C13—C14—C18 | −178.4 (4) |
C5—N1—C1—C2 | 1.5 (6) | C13—C14—C15—C16 | −0.8 (5) |
C6—N2—C7—C8 | 159.8 (3) | C14—C15—C16—C11 | 0.4 (5) |
C6—N2—C10—N3 | 175.0 (3) | C14—C15—C16—C19 | −178.3 (3) |
C7—N2—C6—C5 | 66.3 (4) | C16—C11—C12—C13 | −1.6 (5) |
C7—N2—C10—N3 | −2.1 (5) | C16—C11—C12—C17 | 179.0 (4) |
C7—C8—C9—N3 | −48.7 (5) | C17—C12—C13—C14 | −179.3 (4) |
C9—N3—C10—N2 | 1.5 (5) | C18—C14—C15—C16 | 177.6 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1A···Br1 | 0.85 | 2.46 | 3.292 (4) | 168 |
O1—H1B···N1 | 0.94 (2) | 1.94 (3) | 2.861 (5) | 165 (7) |
C6—H6B···Br1 | 0.97 | 2.87 | 3.815 (3) | 166 |
C3—H3···O1i | 0.93 | 2.54 | 3.442 (6) | 165 |
Symmetry code: (i) −x+1, y−1/2, −z+3/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1A···Br1 | 0.85 | 2.46 | 3.292 (4) | 167.8 |
O1—H1B···N1 | 0.94 (2) | 1.94 (3) | 2.861 (5) | 165 (7) |
C6—H6B···Br1 | 0.97 | 2.87 | 3.815 (3) | 166 |
C3—H3···O1i | 0.93 | 2.54 | 3.442 (6) | 164.7 |
Symmetry code: (i) −x+1, y−1/2, −z+3/2. |
Acknowledgements
The authors thank Ms Y. Zhu for technical assistance. This research was supported by the National Natural Science Foundation of P. R. China (No. 21172055) and the High-level Talents Foundation of Henan University of Technology (11CXRC10).
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N-Heterocyclic carbenes (NHCs) have been widely used as ancillary ligands for the preparation of transition-metal based catalysts (Hopkinson et al., 2014). Chelating NHC metal complexes have attracted particular research interest due to their enhanced stability and modular variability (Mata et al., 2007). Most of the reported chelating NHC metal complexes contain NHC ligands based on imidazole-derived five-membered heterocyclic rings. Ring-expanded NHCs based on six-, seven-, or eight-membered heterocyclic rings possessing enhanced σ-donor ability and easy modular variability began to attract extensive attention in recent years (Dunsford & Cavell, 2014). It would be of interest to explore whether the introduction of ring expanded NHCs to a chelating framework will result in new chelating complexes displaying novel reactivity and enhanced catalytic activities. To the best of our knowledge, no report on chelating NHC metal complexes has been presented. Following our interest in the development of ring-expanded NHCs based on substituted 1,4,5,6-tetrahydropyrimidine and their metal complexes (Mao et al., 2012), and with the intention of synthesizing chelating ring-expanded NHC metal complexes, we synthesized the chelating NHC precursor, 3-methyl-1-(pyridin-2-ylmethyl)-3,4,5,6-tetrahydropyrimidin-1-ium bromide and determined the structure of its monohydrate derivative. Research on the synthesis of carbene-metal complexes containing this ligand is currently in progress.
The molecular structure of the title compound is shown in Figure 1. As expected, the values of the bond distances within the pyrimidinyl ring indicate delocalization of the N═C bond that extends from N2 to N3 through C10, resulting in the increased acidity of the proton on C10 and convenient formation of a carbene functionality. In the cation, the benzene and pyridine rings form a dihedral angle of 14.97 (12)°. In the crystal structure, ions and water molecules are linked by O—H···N, O—H···Br, C—H···Br and C—H···O hydrogen bonds (Table 1) forming chains parallel to the b axis.