Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536809050995/hg2593sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536809050995/hg2593Isup2.hkl |
CCDC reference: 752485
Key indicators
- Single-crystal X-ray study
- T = 200 K
- Mean (C-C) = 0.012 Å
- R factor = 0.048
- wR factor = 0.089
- Data-to-parameter ratio = 19.3
checkCIF/PLATON results
No syntax errors found
Alert level B PLAT222_ALERT_3_B Large Non-Solvent H Ueq(max)/Ueq(min) ... 4.39 Ratio
Alert level C PLAT220_ALERT_2_C Large Non-Solvent C Ueq(max)/Ueq(min) ... 3.68 Ratio PLAT342_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang .. 12 PLAT360_ALERT_2_C Short C(sp3)-C(sp3) Bond C26 - C27 ... 1.40 Ang. PLAT195_ALERT_1_C Missing _cell_measurement_theta_max datum .... ? PLAT196_ALERT_1_C Missing _cell_measurement_theta_min datum .... ? PLAT234_ALERT_4_C Large Hirshfeld Difference C28 -- C29 .. 0.19 Ang. PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L= 0.600 6
0 ALERT level A = In general: serious problem 1 ALERT level B = Potentially serious problem 7 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 2 ALERT type 2 Indicator that the structure model may be wrong or deficient 2 ALERT type 3 Indicator that the structure quality may be low 2 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check
2,6-bis(5-butyl-1H-pyrazol-3-yl)pyridine (200 mg, µmol) was dissolved in acetone (5 ml). After this HAuCl4*xH2O (248 mg, 618 µmol, 49% metal content) in acetonitrile (3 ml) and NaOH (2.5 M in H2O, 741 µl) were added consecutively. The mixture was warmed to 60 °C for 20 min, during this time the initially formed yellow precipitate dissolved. The mixture was subjected to hot filtration and the solvent was removed under reduced pressure. The crude complex was purified by recrystallization from acetone to yield the title compound as red crystals (96.0 mg, 173 µmol, 28%). The compound is stable at RT in air.
1H NMR (300 MHz, acetone): δ=0.93 (t, J=7.3 Hz, 6H, CH3), 1.4 (dm, J=8.5, 7.1 Hz, 4H, CH2), 1.65 (m, 4H, CH2), 2.66 (t, J=7.5 Hz, 4H, CH2), 7.71 (d, J=7.9 Hz, 2H, ArH), 8.25 (t, J=7.9 Hz, 1H, ArH); 13C NMR (75 MHz, acetone): δ = 14.27, 23.13, 32.87, 106.97, 116.38 (no further signals observed, one signal overlapping with solvent at about 29 p.p.m.)
Carbon-bound H-atoms were placed in calculated positions (C–H 0.95– 0.99 Å) and were included in the refinement in the riding model approximation with Uiso(H) set to 1.2–1.5Ueq(C). A staggered group model was used for the methyl groups.
Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT (Siemens, 1996); program(s) used to solve structure: SHELXTL (Sheldrick, 2008a); program(s) used to refine structure: SHELXTL (Sheldrick, 2008a); molecular graphics: SHELXTL (Sheldrick, 2008a); software used to prepare material for publication: SHELXTL (Sheldrick, 2008a).
Fig. 1. Thermal ellipsoid representation of the title compound. Displacement ellipsoids were plotted at 50% probability level. |
[AuCl(C19H23N5)] | Z = 4 |
Mr = 553.84 | F(000) = 1072 |
Monoclinic, P21/c | Dx = 1.850 Mg m−3 |
Hall symbol: -P 2ybc | Mo Kα radiation, λ = 0.71073 Å |
a = 9.0003 (3) Å | Cell parameters from 6701 reflections |
b = 24.2220 (7) Å | µ = 7.55 mm−1 |
c = 9.3042 (3) Å | T = 200 K |
β = 101.372 (1)° | Polyhedron, orange |
V = 1988.54 (11) Å3 | 0.16 × 0.04 × 0.04 mm |
Bruker SMART CCD diffractometer | 4539 independent reflections |
Radiation source: fine-focus sealed tube | 3103 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.091 |
ω scans | θmax = 27.5°, θmin = 1.7° |
Absorption correction: multi-scan SADABS (Sheldrick, 2008b) | h = −11→11 |
Tmin = 0.378, Tmax = 0.752 | k = −31→31 |
19560 measured reflections | l = −12→12 |
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)] = 0.048 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.089 | H-atom parameters constrained |
S = 1.07 | w = 1/[σ2(Fo2) + (0.0241P)2 + 2.5681P] where P = (Fo2 + 2Fc2)/3 |
4539 reflections | (Δ/σ)max = 0.001 |
235 parameters | Δρmax = 0.91 e Å−3 |
0 restraints | Δρmin = −1.01 e Å−3 |
[AuCl(C19H23N5)] | V = 1988.54 (11) Å3 |
Mr = 553.84 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 9.0003 (3) Å | µ = 7.55 mm−1 |
b = 24.2220 (7) Å | T = 200 K |
c = 9.3042 (3) Å | 0.16 × 0.04 × 0.04 mm |
β = 101.372 (1)° |
Bruker SMART CCD diffractometer | 4539 independent reflections |
Absorption correction: multi-scan SADABS (Sheldrick, 2008b) | 3103 reflections with I > 2σ(I) |
Tmin = 0.378, Tmax = 0.752 | Rint = 0.091 |
19560 measured reflections |
R[F2 > 2σ(F2)] = 0.048 | 0 restraints |
wR(F2) = 0.089 | H-atom parameters constrained |
S = 1.07 | Δρmax = 0.91 e Å−3 |
4539 reflections | Δρmin = −1.01 e Å−3 |
235 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 | ||
Au1 | 0.28448 (3) | 0.481560 (12) | 0.61190 (3) | 0.03110 (10) | |
Cl1 | 0.3449 (3) | 0.44522 (9) | 0.8400 (2) | 0.0514 (6) | |
N1 | 0.2300 (7) | 0.5101 (2) | 0.4082 (6) | 0.0347 (15) | |
C2 | 0.1273 (8) | 0.5513 (3) | 0.3826 (8) | 0.0328 (17) | |
C3 | 0.0815 (9) | 0.5696 (3) | 0.2393 (8) | 0.040 (2) | |
H3 | 0.0069 | 0.5977 | 0.2156 | 0.048* | |
C4 | 0.1478 (11) | 0.5458 (3) | 0.1317 (9) | 0.050 (2) | |
H4 | 0.1166 | 0.5578 | 0.0331 | 0.060* | |
C5 | 0.2585 (10) | 0.5050 (3) | 0.1635 (9) | 0.044 (2) | |
H5 | 0.3070 | 0.4906 | 0.0897 | 0.053* | |
C6 | 0.2952 (8) | 0.4865 (3) | 0.3063 (8) | 0.0344 (18) | |
C11 | 0.0767 (8) | 0.5693 (3) | 0.5158 (7) | 0.0316 (18) | |
N12 | 0.1375 (7) | 0.5411 (2) | 0.6419 (6) | 0.0319 (14) | |
N13 | 0.0917 (6) | 0.5633 (2) | 0.7583 (6) | 0.0293 (14) | |
C14 | −0.0014 (8) | 0.6050 (3) | 0.7037 (8) | 0.0311 (17) | |
C15 | −0.0165 (8) | 0.6099 (3) | 0.5537 (8) | 0.0328 (18) | |
H15 | −0.0773 | 0.6355 | 0.4906 | 0.039* | |
C16 | −0.0734 (9) | 0.6395 (3) | 0.8036 (8) | 0.040 (2) | |
H16A | 0.0009 | 0.6458 | 0.8958 | 0.048* | |
H16B | −0.1601 | 0.6190 | 0.8284 | 0.048* | |
C17 | −0.1289 (9) | 0.6948 (3) | 0.7383 (9) | 0.042 (2) | |
H17A | −0.2064 | 0.6882 | 0.6485 | 0.050* | |
H17B | −0.0429 | 0.7142 | 0.7085 | 0.050* | |
C18 | −0.1964 (9) | 0.7326 (3) | 0.8389 (9) | 0.048 (2) | |
H18A | −0.1224 | 0.7370 | 0.9322 | 0.057* | |
H18B | −0.2881 | 0.7149 | 0.8618 | 0.057* | |
C19 | −0.2390 (11) | 0.7898 (4) | 0.7739 (11) | 0.066 (3) | |
H19A | −0.1466 | 0.8108 | 0.7709 | 0.098* | |
H19B | −0.2990 | 0.8094 | 0.8349 | 0.098* | |
H19C | −0.2986 | 0.7858 | 0.6743 | 0.098* | |
C21 | 0.3986 (9) | 0.4418 (3) | 0.3670 (8) | 0.041 (2) | |
N22 | 0.4106 (7) | 0.4319 (3) | 0.5137 (7) | 0.0386 (16) | |
N23 | 0.5062 (8) | 0.3898 (3) | 0.5598 (8) | 0.0465 (18) | |
C24 | 0.5559 (9) | 0.3730 (3) | 0.4398 (11) | 0.049 (2) | |
C25 | 0.4926 (9) | 0.4040 (3) | 0.3161 (10) | 0.049 (2) | |
H25 | 0.5099 | 0.4002 | 0.2191 | 0.058* | |
C26 | 0.6668 (11) | 0.3245 (4) | 0.4558 (13) | 0.071 (3) | |
H26A | 0.7227 | 0.3261 | 0.3744 | 0.085* | |
H26B | 0.7416 | 0.3291 | 0.5484 | 0.085* | |
C27 | 0.6011 (12) | 0.2719 (4) | 0.4563 (15) | 0.093 (4) | |
H27A | 0.5352 | 0.2656 | 0.3592 | 0.112* | |
H27B | 0.5353 | 0.2718 | 0.5299 | 0.112* | |
C28 | 0.7134 (12) | 0.2229 (5) | 0.4898 (16) | 0.094 (4) | |
H28A | 0.7856 | 0.2244 | 0.4221 | 0.113* | |
H28B | 0.7723 | 0.2265 | 0.5911 | 0.113* | |
C29 | 0.6347 (14) | 0.1689 (5) | 0.4739 (15) | 0.114 (5) | |
H29A | 0.5526 | 0.1693 | 0.5293 | 0.171* | |
H29B | 0.7069 | 0.1396 | 0.5119 | 0.171* | |
H29C | 0.5924 | 0.1620 | 0.3701 | 0.171* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Au1 | 0.03813 (17) | 0.03202 (16) | 0.02527 (15) | 0.00177 (16) | 0.01141 (11) | −0.00274 (16) |
Cl1 | 0.0686 (15) | 0.0563 (14) | 0.0304 (11) | 0.0218 (12) | 0.0125 (10) | 0.0075 (10) |
N1 | 0.051 (4) | 0.032 (4) | 0.024 (3) | −0.006 (3) | 0.015 (3) | −0.003 (3) |
C2 | 0.039 (5) | 0.034 (4) | 0.029 (4) | −0.008 (4) | 0.016 (3) | −0.001 (3) |
C3 | 0.053 (5) | 0.040 (5) | 0.026 (4) | 0.001 (4) | 0.005 (4) | 0.005 (4) |
C4 | 0.079 (7) | 0.041 (5) | 0.032 (5) | −0.014 (5) | 0.019 (5) | −0.003 (4) |
C5 | 0.072 (6) | 0.039 (5) | 0.030 (4) | −0.021 (4) | 0.031 (4) | −0.012 (4) |
C6 | 0.045 (5) | 0.040 (5) | 0.024 (4) | −0.014 (4) | 0.021 (3) | −0.010 (4) |
C11 | 0.043 (5) | 0.034 (4) | 0.019 (4) | −0.003 (3) | 0.010 (3) | 0.008 (3) |
N12 | 0.038 (4) | 0.033 (3) | 0.027 (3) | 0.007 (3) | 0.013 (3) | −0.002 (3) |
N13 | 0.029 (3) | 0.039 (4) | 0.022 (3) | 0.001 (3) | 0.010 (3) | −0.008 (3) |
C14 | 0.032 (4) | 0.037 (5) | 0.024 (4) | 0.000 (3) | 0.007 (3) | 0.000 (3) |
C15 | 0.041 (5) | 0.035 (4) | 0.021 (4) | 0.005 (4) | 0.003 (3) | 0.002 (3) |
C16 | 0.041 (5) | 0.048 (5) | 0.031 (4) | 0.005 (4) | 0.006 (4) | −0.003 (4) |
C17 | 0.045 (5) | 0.041 (5) | 0.038 (5) | 0.011 (4) | 0.004 (4) | −0.006 (4) |
C18 | 0.051 (6) | 0.050 (5) | 0.039 (5) | 0.009 (4) | 0.003 (4) | −0.014 (4) |
C19 | 0.080 (7) | 0.042 (6) | 0.067 (7) | 0.018 (5) | −0.005 (5) | −0.018 (5) |
C21 | 0.054 (5) | 0.041 (5) | 0.031 (5) | −0.012 (4) | 0.020 (4) | −0.014 (4) |
N22 | 0.046 (4) | 0.032 (4) | 0.041 (4) | 0.002 (3) | 0.018 (3) | −0.007 (3) |
N23 | 0.047 (4) | 0.034 (4) | 0.067 (5) | 0.001 (3) | 0.031 (4) | 0.001 (4) |
C24 | 0.046 (5) | 0.031 (5) | 0.079 (7) | −0.007 (4) | 0.036 (5) | −0.016 (5) |
C25 | 0.050 (6) | 0.040 (5) | 0.064 (6) | −0.007 (4) | 0.031 (5) | −0.016 (5) |
C26 | 0.075 (7) | 0.041 (6) | 0.106 (9) | −0.002 (5) | 0.041 (6) | −0.018 (6) |
C27 | 0.055 (7) | 0.064 (8) | 0.170 (13) | 0.009 (6) | 0.042 (7) | 0.025 (8) |
C28 | 0.062 (7) | 0.071 (9) | 0.152 (12) | 0.032 (6) | 0.027 (7) | 0.030 (8) |
C29 | 0.104 (11) | 0.092 (11) | 0.141 (13) | 0.044 (9) | 0.011 (9) | 0.018 (10) |
Au1—N1 | 1.985 (6) | C17—H17B | 0.9900 |
Au1—N22 | 1.994 (6) | C18—C19 | 1.529 (11) |
Au1—N12 | 2.014 (6) | C18—H18A | 0.9900 |
Au1—Cl1 | 2.263 (2) | C18—H18B | 0.9900 |
N1—C6 | 1.338 (8) | C19—H19A | 0.9800 |
N1—C2 | 1.349 (9) | C19—H19B | 0.9800 |
C2—C3 | 1.389 (10) | C19—H19C | 0.9800 |
C2—C11 | 1.469 (9) | C21—N22 | 1.369 (9) |
C3—C4 | 1.387 (11) | C21—C25 | 1.390 (11) |
C3—H3 | 0.9500 | N22—N23 | 1.349 (9) |
C4—C5 | 1.394 (12) | N23—C24 | 1.346 (10) |
C4—H4 | 0.9500 | C24—C25 | 1.398 (12) |
C5—C6 | 1.379 (10) | C24—C26 | 1.530 (12) |
C5—H5 | 0.9500 | C25—H25 | 0.9500 |
C6—C21 | 1.466 (11) | C26—C27 | 1.403 (12) |
C11—N12 | 1.374 (9) | C26—H26A | 0.9900 |
C11—C15 | 1.383 (10) | C26—H26B | 0.9900 |
N12—N13 | 1.345 (7) | C27—C28 | 1.551 (13) |
N13—C14 | 1.346 (9) | C27—H27A | 0.9900 |
C14—C15 | 1.381 (9) | C27—H27B | 0.9900 |
C14—C16 | 1.490 (10) | C28—C29 | 1.482 (15) |
C15—H15 | 0.9500 | C28—H28A | 0.9900 |
C16—C17 | 1.515 (10) | C28—H28B | 0.9900 |
C16—H16A | 0.9900 | C29—H29A | 0.9800 |
C16—H16B | 0.9900 | C29—H29B | 0.9800 |
C17—C18 | 1.519 (10) | C29—H29C | 0.9800 |
C17—H17A | 0.9900 | ||
N1—Au1—N22 | 80.1 (3) | C17—C18—C19 | 113.6 (7) |
N1—Au1—N12 | 80.6 (2) | C17—C18—H18A | 108.8 |
N22—Au1—N12 | 160.8 (3) | C19—C18—H18A | 108.8 |
N1—Au1—Cl1 | 177.47 (18) | C17—C18—H18B | 108.8 |
N22—Au1—Cl1 | 98.2 (2) | C19—C18—H18B | 108.8 |
N12—Au1—Cl1 | 101.06 (18) | H18A—C18—H18B | 107.7 |
C6—N1—C2 | 124.9 (6) | C18—C19—H19A | 109.5 |
C6—N1—Au1 | 117.9 (5) | C18—C19—H19B | 109.5 |
C2—N1—Au1 | 117.3 (5) | H19A—C19—H19B | 109.5 |
N1—C2—C3 | 118.0 (7) | C18—C19—H19C | 109.5 |
N1—C2—C11 | 112.7 (6) | H19A—C19—H19C | 109.5 |
C3—C2—C11 | 129.2 (7) | H19B—C19—H19C | 109.5 |
C4—C3—C2 | 118.1 (8) | N22—C21—C25 | 106.9 (8) |
C4—C3—H3 | 120.9 | N22—C21—C6 | 115.6 (6) |
C2—C3—H3 | 120.9 | C25—C21—C6 | 137.5 (8) |
C3—C4—C5 | 122.2 (8) | N23—N22—C21 | 111.6 (6) |
C3—C4—H4 | 118.9 | N23—N22—Au1 | 134.0 (5) |
C5—C4—H4 | 118.9 | C21—N22—Au1 | 114.3 (5) |
C6—C5—C4 | 117.5 (7) | C24—N23—N22 | 105.1 (7) |
C6—C5—H5 | 121.3 | N23—C24—C25 | 111.9 (7) |
C4—C5—H5 | 121.3 | N23—C24—C26 | 117.9 (9) |
N1—C6—C5 | 119.2 (8) | C25—C24—C26 | 130.2 (8) |
N1—C6—C21 | 112.1 (6) | C21—C25—C24 | 104.5 (8) |
C5—C6—C21 | 128.7 (7) | C21—C25—H25 | 127.8 |
N12—C11—C15 | 107.2 (6) | C24—C25—H25 | 127.8 |
N12—C11—C2 | 115.8 (7) | C27—C26—C24 | 115.5 (9) |
C15—C11—C2 | 137.0 (7) | C27—C26—H26A | 108.4 |
N13—N12—C11 | 110.8 (6) | C24—C26—H26A | 108.4 |
N13—N12—Au1 | 135.4 (5) | C27—C26—H26B | 108.4 |
C11—N12—Au1 | 113.6 (5) | C24—C26—H26B | 108.4 |
N12—N13—C14 | 105.2 (5) | H26A—C26—H26B | 107.5 |
N13—C14—C15 | 112.1 (6) | C26—C27—C28 | 115.9 (9) |
N13—C14—C16 | 120.0 (6) | C26—C27—H27A | 108.3 |
C15—C14—C16 | 127.9 (7) | C28—C27—H27A | 108.3 |
C14—C15—C11 | 104.6 (6) | C26—C27—H27B | 108.3 |
C14—C15—H15 | 127.7 | C28—C27—H27B | 108.3 |
C11—C15—H15 | 127.7 | H27A—C27—H27B | 107.4 |
C14—C16—C17 | 113.3 (6) | C29—C28—C27 | 112.1 (9) |
C14—C16—H16A | 108.9 | C29—C28—H28A | 109.2 |
C17—C16—H16A | 108.9 | C27—C28—H28A | 109.2 |
C14—C16—H16B | 108.9 | C29—C28—H28B | 109.2 |
C17—C16—H16B | 108.9 | C27—C28—H28B | 109.2 |
H16A—C16—H16B | 107.7 | H28A—C28—H28B | 107.9 |
C16—C17—C18 | 115.2 (7) | C28—C29—H29A | 109.5 |
C16—C17—H17A | 108.5 | C28—C29—H29B | 109.5 |
C18—C17—H17A | 108.5 | H29A—C29—H29B | 109.5 |
C16—C17—H17B | 108.5 | C28—C29—H29C | 109.5 |
C18—C17—H17B | 108.5 | H29A—C29—H29C | 109.5 |
H17A—C17—H17B | 107.5 | H29B—C29—H29C | 109.5 |
Experimental details
Crystal data | |
Chemical formula | [AuCl(C19H23N5)] |
Mr | 553.84 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 200 |
a, b, c (Å) | 9.0003 (3), 24.2220 (7), 9.3042 (3) |
β (°) | 101.372 (1) |
V (Å3) | 1988.54 (11) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 7.55 |
Crystal size (mm) | 0.16 × 0.04 × 0.04 |
Data collection | |
Diffractometer | Bruker SMART CCD diffractometer |
Absorption correction | Multi-scan SADABS (Sheldrick, 2008b) |
Tmin, Tmax | 0.378, 0.752 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 19560, 4539, 3103 |
Rint | 0.091 |
(sin θ/λ)max (Å−1) | 0.649 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.048, 0.089, 1.07 |
No. of reflections | 4539 |
No. of parameters | 235 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.91, −1.01 |
Computer programs: SMART (Siemens, 1996), SAINT (Siemens, 1996), SHELXTL (Sheldrick, 2008a).
Catalysis of organic reactions by gold complexes has become a very important area of research in the past decade (Hashmi & Hutchings, 2006a, 2006b; Hashmi, 2007). While the field is dominated by gold(I) complexes (Ito et al., 1986), the use of gold(III) pre-catalysts is also of interest (Hashmi et al., 2004a, 2004b). Here we report the structural details of a new representative of the gold(III) pre-catalysts. The main feature of this structure is the ring strain of the two 5-membered metallacycles that were built up by the pincer ligand and the gold center. The theoretical sum of the bond angles in these flat 5-membered metallacycles is 540.0°, as it was observed in both cases. For a hypothetic strain-free (ring-opened) molecule simple geometrical considerations result an angle sum of about 582° (90° at Au1, 120° at N1, C2, C6, and 126° at C11, N12 C21, N22). The required adaption of 42° is achieved by bending the bond angles (mean values over both rings) at Au1 (9.7°), N1 (2.4°), C2/C6 (7.6°), C11/C21 (10.3°), and N12/N22 (12.0°). As expected the bending at the pyridin nitrogen atom N1 is by far least, as the aromatic ring itself is rigid and cannot bend on two sides simultaneously.