supplementary materials


zs2253 scheme

Acta Cryst. (2013). E69, o971    [ doi:10.1107/S1600536813013858 ]

1-(4-Chlorophenyl)-2-(1,3-diazepan-2-ylidene)ethanone

X.-W. Zhang, J.-H. Xia, Z.-H. Xu, L.-B. Wang and C.-Y. Yu

Abstract top

In the title compound, C13H15ClN2O, there are two crystallographically independent but conformationally similar (E)-molecules in the asymmetric unit [dihedral angles between the phenyl ring and a common planar fragment of the 1,3-diazepane moiety = 47.34 (16) and 48.00 (16)°]. The seven-membered ring system adopts a chair conformation in both molecules. In the crystal, N-H...O hydrogen bonds lead to chains extending along the b-axis direction.

Comment top

Heterocyclic ketene aminals are viewed as a useful synthon for the synthesis of fused heterocycles (Huang & Wang, 1994). Also, some of these compounds display certain bioactivities and show potential for applications in the fields of pesticides and medicine, e.g. as antimicrobial reagents (Kondo et al., 1990) and anti-anxiety reagents (Jordan et al., 2002). In the title compound, C13H15ClN2O, there are two crystallographically independent but similar (E)-molecules in the asymmetric unit (Fig. 1), with the dihedral angle between the phenyl ring and the ethylenic moiety [(C8–C13) and N1, N2, C5, C6 in molecule 1 and (C21–C26) and (N3, N4, C18, C19) in molecule 2] being 47.34 (16) and 48.00 (16)°, respectively. Intramolecular interactions (N1—H···O1 in molecule 1 and N4—H···O2 in molecule 2) (Table 1) stabilize the conformations. The seven-membered ring adopts a stable chair conformation. In the crystal, intermolecular N—H···O hydrogen-bonding interactions (Table 1) give one-dimensional chains which extend down b (Fig. 2).

Related literature top

Heterocyclic ketene aminals are a useful synthon for the synthesis of fused heterocycles, see: Huang & Wang (1994). For their bioactivity and potential applications as pesticides and in medicine, see: Kondo et al. (1990); Jordan et al. (2002). For the synthesis, see: Huang & Liu (1989). For a similar structure, see: Yu et al. (2006).

Experimental top

The title compound was prepared according to the method of Huang & Liu (1989). m.p. 448–450 K. MS: m/z = 250 (M+). IR: 3180 (NH), 1630 (C=O), 1578 cm-l (C=C). 1H-NMR: δ = 7.70 (d, 2H), 7.40 (d, 2H), 11.13 (s, lH), 7.10 (s, lH), 5.27 (s, lH), 3.05–3.30 (m, 4H), 1.55–1.72 (m, 4H) p.p.m.. 13C-NMR: δ = 179.7, 168.4, 140.2, 133.4, 127.7, 127.4, 79.1, 43.8, 27.6 p.p.m.. Anal. calc. for C13H15ClN2O: C, 62.27; H, 6.03; N, 11.18. Found C, 62.09; H, 5.94; N, 11.02.

Refinement top

H atoms were positioned geometrically and refined using a riding model, with C—H = 0.99 Å (methylene) or 0.95 Å (aromatic) and N—H = 0.88 Å (N), with Uiso(H) = 1.5Ueq(C) (methylene) or Uiso(H) = 1.2 Ueq(aromatic C or N).

Computing details top

Data collection: CrystalClear (Rigaku, 2007); cell refinement: CrystalClear (Rigaku, 2007); data reduction: CrystalClear (Rigaku, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX-2 (Dolomanov et al., 2009); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure and atom numbering scheme for the two independent molecules in the asymmetric unit of the title compound. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as spheres of arbitrary radius.
[Figure 2] Fig. 2. The packing of the title compound in the unit cell. Dashed lines indicate N—H···O hydrogen bonds and intramolecular N—H···O interactions. For symmetry code (i), see Table 1.
1-(4-Chlorophenyl)-2-(1,3-diazepan-2-ylidene)ethanone top
Crystal data top
C13H15ClN2OZ = 4
Mr = 250.72F(000) = 528
Triclinic, P1Dx = 1.305 Mg m3
Hall symbol: -P 1Melting point = 448–450 K
a = 10.779 (4) ÅMo Kα radiation, λ = 0.71073 Å
b = 10.815 (3) ÅCell parameters from 3768 reflections
c = 12.158 (4) Åθ = 1.8–27.5°
α = 96.091 (4)°µ = 0.29 mm1
β = 110.710 (4)°T = 173 K
γ = 101.244 (4)°Block, white
V = 1276.4 (7) Å30.25 × 0.15 × 0.14 mm
Data collection top
Rigaku Saturn724+ CCD
diffractometer
5780 independent reflections
Radiation source: sealed tube4854 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.048
ω scans at fixed χ = 45°θmax = 27.5°, θmin = 2.1°
Absorption correction: multi-scan
(CrystalClear; Rigaku, 2007)
h = 1313
Tmin = 0.606, Tmax = 1.000k = 1413
11344 measured reflectionsl = 1515
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.075Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.162H-atom parameters constrained
S = 1.12 w = 1/[σ2(Fo2) + (0.0466P)2 + 1.3126P]
where P = (Fo2 + 2Fc2)/3
5780 reflections(Δ/σ)max < 0.001
307 parametersΔρmax = 0.49 e Å3
0 restraintsΔρmin = 0.42 e Å3
Crystal data top
C13H15ClN2Oγ = 101.244 (4)°
Mr = 250.72V = 1276.4 (7) Å3
Triclinic, P1Z = 4
a = 10.779 (4) ÅMo Kα radiation
b = 10.815 (3) ŵ = 0.29 mm1
c = 12.158 (4) ÅT = 173 K
α = 96.091 (4)°0.25 × 0.15 × 0.14 mm
β = 110.710 (4)°
Data collection top
Rigaku Saturn724+ CCD
diffractometer
5780 independent reflections
Absorption correction: multi-scan
(CrystalClear; Rigaku, 2007)
4854 reflections with I > 2σ(I)
Tmin = 0.606, Tmax = 1.000Rint = 0.048
11344 measured reflectionsθmax = 27.5°
Refinement top
R[F2 > 2σ(F2)] = 0.075H-atom parameters constrained
wR(F2) = 0.162Δρmax = 0.49 e Å3
S = 1.12Δρmin = 0.42 e Å3
5780 reflectionsAbsolute structure: ?
307 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cl10.01481 (9)0.17456 (9)0.95043 (7)0.0515 (2)
Cl0.43184 (9)0.64786 (9)0.02814 (7)0.0516 (2)
O10.3033 (2)0.92241 (17)0.48282 (17)0.0311 (4)
O20.2480 (2)0.42103 (17)0.56002 (18)0.0335 (5)
N10.1989 (2)0.8486 (2)0.6444 (2)0.0305 (5)
H10.18680.90350.59540.037*
N20.1648 (2)0.6291 (2)0.6502 (2)0.0315 (5)
H20.21180.57040.65550.038*
N30.3217 (2)0.1261 (2)0.3506 (2)0.0305 (5)
H30.34860.06770.39210.037*
N40.3187 (2)0.3421 (2)0.3784 (2)0.0304 (5)
H40.26330.39130.38100.036*
C10.2192 (3)0.8941 (3)0.7685 (3)0.0360 (7)
H1A0.23640.98890.78270.043*
H1B0.30230.87260.82190.043*
C20.1006 (3)0.8396 (3)0.8037 (3)0.0414 (7)
H2A0.01440.84830.74290.050*
H2B0.11380.89060.88130.050*
C30.0865 (4)0.6990 (3)0.8145 (3)0.0413 (7)
H3A0.17240.69030.87550.050*
H3B0.01170.67130.84270.050*
C40.0566 (3)0.6115 (3)0.6977 (3)0.0343 (6)
H4A0.03620.52160.70890.041*
H4B0.02730.62390.63660.041*
C50.1976 (3)0.7281 (2)0.5993 (2)0.0275 (6)
C60.2322 (3)0.7060 (2)0.4985 (2)0.0268 (5)
H60.21980.61940.46350.032*
C70.2834 (3)0.8023 (2)0.4467 (2)0.0258 (5)
C80.3180 (3)0.7624 (2)0.3414 (2)0.0259 (5)
C90.2356 (3)0.6569 (3)0.2512 (3)0.0327 (6)
H90.15520.60790.25640.039*
C100.2687 (3)0.6221 (3)0.1543 (3)0.0359 (6)
H100.21110.55080.09270.043*
C110.3869 (3)0.6927 (3)0.1485 (2)0.0337 (6)
C120.4705 (3)0.7977 (3)0.2366 (3)0.0365 (7)
H120.55200.84510.23190.044*
C130.4345 (3)0.8334 (3)0.3316 (2)0.0314 (6)
H130.49010.90730.39080.038*
C140.3117 (3)0.1092 (3)0.2266 (3)0.0354 (6)
H14A0.22310.12350.17550.042*
H14B0.31100.01920.20050.042*
C150.4259 (4)0.1975 (3)0.2056 (3)0.0441 (8)
H15A0.42110.16790.12390.053*
H15B0.51530.19170.26340.053*
C160.4181 (4)0.3370 (3)0.2190 (3)0.0467 (8)
H16A0.49100.38870.19930.056*
H16B0.32870.34280.16120.056*
C170.4338 (3)0.3927 (3)0.3444 (3)0.0353 (6)
H17A0.51780.37680.40220.042*
H17B0.44730.48690.35190.042*
C180.2926 (3)0.2248 (2)0.4058 (2)0.0267 (5)
C190.2356 (3)0.2047 (2)0.4922 (2)0.0274 (5)
H190.20610.11880.50060.033*
C200.2198 (3)0.3026 (2)0.5660 (2)0.0266 (5)
C210.1675 (3)0.2680 (2)0.6605 (2)0.0258 (5)
C220.0618 (3)0.1599 (3)0.6392 (2)0.0299 (6)
H220.02220.10470.56280.036*
C230.0134 (3)0.1315 (3)0.7275 (3)0.0321 (6)
H230.06010.05870.71180.039*
C240.0741 (3)0.2111 (3)0.8384 (2)0.0332 (6)
C250.1789 (3)0.3185 (3)0.8625 (3)0.0392 (7)
H250.21960.37190.93980.047*
C260.2243 (3)0.3477 (3)0.7732 (3)0.0351 (6)
H260.29500.42290.78870.042*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0604 (5)0.0674 (6)0.0365 (4)0.0123 (4)0.0303 (4)0.0159 (4)
Cl0.0496 (5)0.0742 (6)0.0351 (4)0.0167 (4)0.0236 (4)0.0008 (4)
O10.0418 (11)0.0198 (9)0.0341 (10)0.0049 (8)0.0194 (9)0.0035 (8)
O20.0467 (12)0.0222 (9)0.0404 (11)0.0098 (8)0.0253 (10)0.0091 (8)
N10.0413 (13)0.0250 (11)0.0303 (12)0.0103 (10)0.0179 (10)0.0077 (10)
N20.0431 (14)0.0246 (11)0.0374 (13)0.0120 (10)0.0243 (11)0.0116 (10)
N30.0437 (14)0.0269 (11)0.0280 (12)0.0122 (10)0.0195 (10)0.0078 (9)
N40.0349 (12)0.0264 (11)0.0383 (13)0.0115 (10)0.0196 (11)0.0144 (10)
C10.0420 (17)0.0338 (15)0.0312 (15)0.0068 (13)0.0169 (13)0.0027 (12)
C20.0494 (19)0.0418 (17)0.0387 (17)0.0122 (14)0.0251 (15)0.0019 (14)
C30.0521 (19)0.0480 (18)0.0365 (16)0.0151 (15)0.0293 (15)0.0124 (14)
C40.0371 (15)0.0328 (15)0.0395 (16)0.0073 (12)0.0215 (13)0.0120 (13)
C50.0281 (13)0.0233 (12)0.0318 (14)0.0061 (10)0.0129 (11)0.0036 (11)
C60.0343 (14)0.0194 (12)0.0286 (13)0.0064 (10)0.0149 (11)0.0022 (10)
C70.0257 (12)0.0226 (12)0.0274 (13)0.0047 (10)0.0090 (10)0.0049 (10)
C80.0308 (14)0.0217 (12)0.0269 (13)0.0063 (10)0.0128 (11)0.0062 (10)
C90.0355 (15)0.0280 (14)0.0337 (15)0.0016 (11)0.0163 (12)0.0035 (12)
C100.0408 (16)0.0325 (15)0.0298 (14)0.0049 (12)0.0130 (12)0.0026 (12)
C110.0411 (16)0.0417 (16)0.0250 (13)0.0176 (13)0.0168 (12)0.0061 (12)
C120.0305 (14)0.0448 (17)0.0355 (15)0.0061 (12)0.0165 (12)0.0056 (13)
C130.0312 (14)0.0295 (14)0.0298 (14)0.0032 (11)0.0108 (11)0.0015 (11)
C140.0441 (17)0.0347 (15)0.0288 (14)0.0089 (13)0.0170 (13)0.0034 (12)
C150.055 (2)0.0457 (18)0.0421 (18)0.0109 (15)0.0318 (16)0.0065 (15)
C160.062 (2)0.0445 (18)0.0451 (19)0.0070 (16)0.0354 (17)0.0141 (15)
C170.0343 (15)0.0319 (15)0.0404 (16)0.0018 (12)0.0188 (13)0.0068 (13)
C180.0283 (13)0.0266 (13)0.0251 (13)0.0081 (10)0.0094 (11)0.0047 (11)
C190.0345 (14)0.0201 (12)0.0318 (14)0.0067 (10)0.0170 (12)0.0078 (11)
C200.0315 (13)0.0221 (12)0.0271 (13)0.0064 (10)0.0120 (11)0.0068 (10)
C210.0286 (13)0.0246 (12)0.0265 (13)0.0091 (10)0.0117 (11)0.0058 (10)
C220.0353 (14)0.0265 (13)0.0279 (13)0.0059 (11)0.0139 (11)0.0024 (11)
C230.0337 (15)0.0301 (14)0.0341 (15)0.0049 (11)0.0162 (12)0.0075 (12)
C240.0381 (16)0.0408 (16)0.0273 (14)0.0123 (13)0.0182 (12)0.0092 (12)
C250.0468 (18)0.0394 (16)0.0261 (14)0.0049 (14)0.0128 (13)0.0013 (12)
C260.0405 (16)0.0288 (14)0.0302 (15)0.0005 (12)0.0131 (13)0.0006 (12)
Geometric parameters (Å, º) top
Cl1—C241.747 (3)C9—C101.383 (4)
Cl—C111.747 (3)C9—H90.9500
O1—C71.277 (3)C10—C111.381 (4)
O2—C201.273 (3)C10—H100.9500
N1—C51.354 (3)C11—C121.382 (4)
N1—C11.461 (3)C12—C131.383 (4)
N1—H10.8800C12—H120.9500
N2—C51.344 (3)C13—H130.9500
N2—C41.463 (3)C14—C151.519 (4)
N2—H20.8800C14—H14A0.9900
N3—C181.347 (3)C14—H14B0.9900
N3—C141.461 (3)C15—C161.522 (5)
N3—H30.8800C15—H15A0.9900
N4—C181.348 (3)C15—H15B0.9900
N4—C171.468 (3)C16—C171.515 (4)
N4—H40.8800C16—H16A0.9900
C1—C21.520 (4)C16—H16B0.9900
C1—H1A0.9900C17—H17A0.9900
C1—H1B0.9900C17—H17B0.9900
C2—C31.522 (4)C18—C191.407 (4)
C2—H2A0.9900C19—C201.390 (4)
C2—H2B0.9900C19—H190.9500
C3—C41.513 (4)C20—C211.499 (4)
C3—H3A0.9900C21—C221.392 (4)
C3—H3B0.9900C21—C261.395 (4)
C4—H4A0.9900C22—C231.387 (4)
C4—H4B0.9900C22—H220.9500
C5—C61.412 (4)C23—C241.377 (4)
C6—C71.396 (4)C23—H230.9500
C6—H60.9500C24—C251.376 (4)
C7—C81.499 (4)C25—C261.381 (4)
C8—C131.390 (4)C25—H250.9500
C8—C91.394 (4)C26—H260.9500
C5—N1—C1124.8 (2)C11—C12—C13119.4 (3)
C5—N1—H1117.6C11—C12—H12120.3
C1—N1—H1117.6C13—C12—H12120.3
C5—N2—C4124.8 (2)C12—C13—C8120.8 (3)
C5—N2—H2117.6C12—C13—H13119.6
C4—N2—H2117.6C8—C13—H13119.6
C18—N3—C14124.7 (2)N3—C14—C15115.0 (2)
C18—N3—H3117.7N3—C14—H14A108.5
C14—N3—H3117.7C15—C14—H14A108.5
C18—N4—C17124.0 (2)N3—C14—H14B108.5
C18—N4—H4118.0C15—C14—H14B108.5
C17—N4—H4118.0H14A—C14—H14B107.5
N1—C1—C2115.2 (2)C14—C15—C16112.7 (3)
N1—C1—H1A108.5C14—C15—H15A109.1
C2—C1—H1A108.5C16—C15—H15A109.1
N1—C1—H1B108.5C14—C15—H15B109.1
C2—C1—H1B108.5C16—C15—H15B109.1
H1A—C1—H1B107.5H15A—C15—H15B107.8
C1—C2—C3113.2 (3)C17—C16—C15112.6 (3)
C1—C2—H2A108.9C17—C16—H16A109.1
C3—C2—H2A108.9C15—C16—H16A109.1
C1—C2—H2B108.9C17—C16—H16B109.1
C3—C2—H2B108.9C15—C16—H16B109.1
H2A—C2—H2B107.8H16A—C16—H16B107.8
C4—C3—C2113.0 (2)N4—C17—C16115.5 (3)
C4—C3—H3A109.0N4—C17—H17A108.4
C2—C3—H3A109.0C16—C17—H17A108.4
C4—C3—H3B109.0N4—C17—H17B108.4
C2—C3—H3B109.0C16—C17—H17B108.4
H3A—C3—H3B107.8H17A—C17—H17B107.5
N2—C4—C3116.3 (2)N3—C18—N4119.9 (2)
N2—C4—H4A108.2N3—C18—C19119.7 (2)
C3—C4—H4A108.2N4—C18—C19120.4 (2)
N2—C4—H4B108.2C20—C19—C18124.1 (2)
C3—C4—H4B108.2C20—C19—H19117.9
H4A—C4—H4B107.4C18—C19—H19117.9
N2—C5—N1120.6 (2)O2—C20—C19124.6 (2)
N2—C5—C6119.4 (2)O2—C20—C21117.1 (2)
N1—C5—C6120.0 (2)C19—C20—C21118.4 (2)
C7—C6—C5124.6 (2)C22—C21—C26118.6 (2)
C7—C6—H6117.7C22—C21—C20122.2 (2)
C5—C6—H6117.7C26—C21—C20119.2 (2)
O1—C7—C6124.6 (2)C23—C22—C21121.1 (3)
O1—C7—C8117.5 (2)C23—C22—H22119.5
C6—C7—C8117.9 (2)C21—C22—H22119.5
C13—C8—C9118.4 (2)C24—C23—C22118.6 (3)
C13—C8—C7119.4 (2)C24—C23—H23120.7
C9—C8—C7122.1 (2)C22—C23—H23120.7
C10—C9—C8121.3 (3)C25—C24—C23121.8 (3)
C10—C9—H9119.4C25—C24—Cl1119.5 (2)
C8—C9—H9119.4C23—C24—Cl1118.7 (2)
C11—C10—C9118.9 (3)C24—C25—C26119.2 (3)
C11—C10—H10120.6C24—C25—H25120.4
C9—C10—H10120.6C26—C25—H25120.4
C10—C11—C12121.1 (3)C25—C26—C21120.7 (3)
C10—C11—Cl119.4 (2)C25—C26—H26119.6
C12—C11—Cl119.5 (2)C21—C26—H26119.6
C5—N1—C1—C270.7 (4)C18—N3—C14—C1575.0 (4)
N1—C1—C2—C372.1 (4)N3—C14—C15—C1669.8 (4)
C1—C2—C3—C462.4 (4)C14—C15—C16—C1762.4 (4)
C5—N2—C4—C373.6 (4)C18—N4—C17—C1674.6 (4)
C2—C3—C4—N265.7 (4)C15—C16—C17—N469.9 (4)
C4—N2—C5—N139.6 (4)C14—N3—C18—N433.7 (4)
C4—N2—C5—C6141.0 (3)C14—N3—C18—C19146.5 (3)
C1—N1—C5—N224.8 (4)C17—N4—C18—N333.2 (4)
C1—N1—C5—C6154.5 (3)C17—N4—C18—C19146.6 (3)
N2—C5—C6—C7172.1 (3)N3—C18—C19—C20170.6 (3)
N1—C5—C6—C77.3 (4)N4—C18—C19—C209.2 (4)
C5—C6—C7—O11.1 (4)C18—C19—C20—O23.9 (4)
C5—C6—C7—C8178.7 (2)C18—C19—C20—C21175.3 (2)
O1—C7—C8—C1339.3 (4)O2—C20—C21—C22139.5 (3)
C6—C7—C8—C13140.5 (3)C19—C20—C21—C2241.2 (4)
O1—C7—C8—C9139.7 (3)O2—C20—C21—C2639.2 (4)
C6—C7—C8—C940.5 (4)C19—C20—C21—C26140.1 (3)
C13—C8—C9—C100.5 (4)C26—C21—C22—C230.1 (4)
C7—C8—C9—C10179.5 (3)C20—C21—C22—C23178.6 (3)
C8—C9—C10—C111.0 (4)C21—C22—C23—C241.4 (4)
C9—C10—C11—C121.0 (5)C22—C23—C24—C251.3 (4)
C9—C10—C11—Cl178.7 (2)C22—C23—C24—Cl1179.2 (2)
C10—C11—C12—C130.6 (5)C23—C24—C25—C260.3 (5)
Cl—C11—C12—C13179.8 (2)Cl1—C24—C25—C26179.3 (2)
C11—C12—C13—C82.1 (4)C24—C25—C26—C211.6 (5)
C9—C8—C13—C122.1 (4)C22—C21—C26—C251.5 (4)
C7—C8—C13—C12178.9 (3)C20—C21—C26—C25179.8 (3)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N1—H1···O10.882.162.704 (3)119
N2—H2···O20.882.072.834 (3)145
N3—H3···O1i0.882.092.878 (3)149
N4—H4···O20.882.232.689 (3)112
C6—H6···O20.952.573.270 (3)131
C13—H13···O1ii0.952.473.372 (4)159
C19—H19···O1i0.952.573.274 (3)132
Symmetry codes: (i) x, y1, z; (ii) x+1, y+2, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
N2—H2···O20.882.072.834 (3)145
N3—H3···O1i0.882.092.878 (3)149
Symmetry code: (i) x, y1, z.
Acknowledgements top

We thank Tongling Liang at the Chinese Academy of Sciences for the X-ray crystallographic determination.

references
References top

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