supplementary materials


hy2606 scheme

Acta Cryst. (2013). E69, m31-m32    [ doi:10.1107/S1600536812049197 ]

[2,6-Bis(5-ethoxy-1,3-oxazol-2-yl)-4-methoxyphenyl-[kappa]3N,C1,N']bromidopalladium(II)

W.-H. Nan, J.-P. Tan and Q.-L. Luo

Abstract top

In the title compound, [PdBr(C17H17N2O5)], the PdII atom is coordinated by an N,C1,N'-tridentate pincer ligand and a Br atom in a distorted square-planar geometry. In the crystal, molecules are connected by C-H...Br and C-H...O hydrogen bonds, and [pi]-[pi] interactions between the oxazole and benzene rings [centroid-centroid distance = 3.7344 (19) Å], resulting in a three-dimensional supramolecular structure.

Comment top

Cross-coupling reactions catalyzed by palladium complexes are among the most important tools for C—C bond construction. Considerable attention has recently been devoted to pincer-Pd complexes due to their catalytic abilities (Ghorai et al., 2012; van Koten & Gebbink, 2011; Moreno et al., 2010; Selander & Szabó, 2011). We are interested in the NCN type of pincer-Pd complexes (Luo et al., 2007, 2011, 2012; Xu et al., 2011) as a variety of nonphosphine pincer catalytic system, that contains two nitrogen atoms as donating sites in the coordination sphere (Hao et al., 2010; Young et al., 2011)

The title compound was conveniently synthesized from the reaction of Pd(dba)2 (dba = dibenzylideneacetone) with 1-bromo-2,6-bis(5-ethoxyoxazol-2-yl)-4-methoxy benzene in dry benzene under reflux in an argon atmosphere. As a result, the title compound was isolated with 84% yield. Suitable single crystals were grown via vapor diffusion of hexane into a DMF solution of the soluble reaction product at room temperature for dozens of days.

The molecular structure is shown in Fig. 1 and selected bond lengths in Table 1. In the crystal, the molecules are linked by intermolecular C—H···Br and C—H···O hydrogen bonds (Table 2) and ππ interactions between the oxazole and benzene rings [centroid–centroid distance = 3.7344 (19) Å], resulting in a three-dimensional supramolecular structure.

Related literature top

For background to pincer palladium complexes, see: van Koten & Gebbink (2011); Moreno et al. (2010); Selander & Szabó (2011). For palladium complexes with NCN pincer ligands, see: Hao et al. (2010); Young et al. (2011). For studies on the chemistry of bis(oxazole) pincer palladium complexes, see: Luo et al. (2007, 2011); Xu et al. (2011). For structures of related bis(azole) pincer palladium complexes, see: Ghorai et al. (2012); Luo et al. (2012).

Experimental top

Under an argon atmosphere, a 25 ml Schlenk flask was charged with 1-bromo-2,6-bis(5-ethoxyoxazol-2-yl)-4-methoxybenzene (106 mg, 0.3 mmol), Pd(dba)2 (173 mg, 0.3 mmol) and dry benzene (15 ml). The reaction mixture was heated and refluxed for 2 h, and then cooled to room temperature and stirred for further 2 h. The resultant mixture was directly transferred on to a diatomite column and eluted first with hexane to remove dibenzylideneacetone and then with chloroform. The collected target compound was crystallized from CHCl3/MeOH as a slight yellow solid (yield: 84%). 1H NMR (300 MHz, CDCl3): δ 6.76 (s, 2H), 6.52 (s, 2H), 4.25 (q, 4H, 3J = 6.9 Hz), 3.83 (s, 3H), 1.49 (t, 6H, 3J = 7.0 Hz). 13C NMR (75 MHz, CDCl3): δ159.3, 158.5, 157.6, 154.7, 129.9, 107.3, 100.3, 55.8, 14.4. LRMS (ESI): m/z(%) 951 (100) (2M+–Br).

Refinement top

H atoms were positioned geometrically and refined as riding atoms, with C–H = 0.93 (aromatic), 0.96 (CH3) and 0.97 (CH2) Å and with Uiso(H) = 1.2(1.5 for methyl)Ueq(C).

Computing details top

Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound. Displacement ellipsoids are drawn at the 30% probability level.
[2,6-Bis(5-ethoxy-1,3-oxazol-2-yl)-4-methoxyphenyl- κ3N,C1,N']bromidopalladium(II) top
Crystal data top
[PdBr(C17H17N2O5)]Z = 2
Mr = 515.64F(000) = 508
Triclinic, P1Dx = 1.810 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71073 Å
a = 9.0209 (3) ÅCell parameters from 15776 reflections
b = 9.6544 (3) Åθ = 1.9–27.5°
c = 10.9200 (3) ŵ = 3.12 mm1
α = 87.093 (2)°T = 296 K
β = 86.974 (1)°Block, yellow
γ = 85.793 (2)°0.43 × 0.41 × 0.37 mm
V = 946.11 (5) Å3
Data collection top
Bruker APEX CCD
diffractometer
4311 independent reflections
Radiation source: fine-focus sealed tube3770 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.034
Detector resolution: 0.01 pixels mm-1θmax = 27.5°, θmin = 1.9°
φ and ω scansh = 1111
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
k = 1212
Tmin = 0.347, Tmax = 0.391l = 1413
15776 measured reflections
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)] = 0.036Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.113H-atom parameters constrained
S = 1.08 w = 1/[σ2(Fo2) + (0.080P)2]
where P = (Fo2 + 2Fc2)/3
4311 reflections(Δ/σ)max < 0.001
235 parametersΔρmax = 0.72 e Å3
6 restraintsΔρmin = 1.25 e Å3
Crystal data top
[PdBr(C17H17N2O5)]γ = 85.793 (2)°
Mr = 515.64V = 946.11 (5) Å3
Triclinic, P1Z = 2
a = 9.0209 (3) ÅMo Kα radiation
b = 9.6544 (3) ŵ = 3.12 mm1
c = 10.9200 (3) ÅT = 296 K
α = 87.093 (2)°0.43 × 0.41 × 0.37 mm
β = 86.974 (1)°
Data collection top
Bruker APEX CCD
diffractometer
4311 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)
3770 reflections with I > 2σ(I)
Tmin = 0.347, Tmax = 0.391Rint = 0.034
15776 measured reflectionsθmax = 27.5°
Refinement top
R[F2 > 2σ(F2)] = 0.036H-atom parameters constrained
wR(F2) = 0.113Δρmax = 0.72 e Å3
S = 1.08Δρmin = 1.25 e Å3
4311 reflectionsAbsolute structure: ?
235 parametersFlack parameter: ?
6 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
Pd10.75135 (2)0.11221 (2)0.04359 (2)0.03536 (11)
Br10.73062 (5)0.33747 (4)0.14750 (4)0.06338 (15)
O11.1647 (3)0.2444 (3)0.3330 (3)0.0641 (8)
O21.0326 (3)0.0693 (2)0.2594 (2)0.0427 (5)
O30.7890 (3)0.4275 (2)0.2212 (3)0.0579 (7)
O40.4921 (3)0.1921 (2)0.1850 (2)0.0442 (5)
O50.3381 (3)0.1541 (3)0.3498 (2)0.0668 (8)
N10.9050 (3)0.1515 (3)0.0974 (2)0.0396 (6)
N20.6019 (3)0.0043 (3)0.1522 (2)0.0400 (6)
C11.3044 (8)0.4175 (6)0.4370 (6)0.106 (2)
H1A1.32640.51340.43950.158*
H1B1.26340.39710.51280.158*
H1C1.39410.35950.42530.158*
C21.1945 (6)0.3901 (4)0.3332 (5)0.0810 (14)
H2A1.23460.41050.25600.097*
H2B1.10330.44830.34390.097*
C31.0668 (4)0.2043 (3)0.2459 (3)0.0447 (7)
C40.9916 (4)0.2562 (3)0.1487 (3)0.0426 (7)
H4A0.99570.34500.12030.051*
C50.9345 (3)0.0438 (3)0.1655 (3)0.0372 (6)
C60.8596 (3)0.0824 (3)0.1380 (3)0.0372 (6)
C70.8675 (4)0.2063 (3)0.1977 (3)0.0414 (7)
H7A0.93310.22010.26530.050*
C80.7764 (4)0.3086 (3)0.1552 (3)0.0436 (7)
C90.6796 (4)0.2931 (3)0.0517 (3)0.0412 (7)
H9A0.61960.36350.02330.049*
C100.6764 (3)0.1684 (3)0.0073 (3)0.0376 (7)
C110.7643 (3)0.0646 (3)0.0372 (3)0.0358 (6)
C120.5894 (3)0.1220 (3)0.1135 (3)0.0384 (6)
C130.5062 (4)0.0193 (4)0.2543 (3)0.0442 (7)
H13A0.49050.09730.30110.053*
C140.4399 (4)0.1014 (4)0.2730 (3)0.0464 (8)
C150.2843 (5)0.0696 (5)0.4494 (4)0.0643 (11)
H15A0.23210.01530.41830.077*
H15B0.36660.04500.49570.077*
C160.1823 (6)0.1520 (5)0.5285 (4)0.0837 (16)
H16A0.14400.09840.59630.126*
H16B0.23510.23560.55880.126*
H16C0.10130.17550.48170.126*
C170.6779 (5)0.5245 (4)0.1992 (4)0.0587 (10)
H17A0.69990.60180.25080.088*
H17B0.58240.48010.21740.088*
H17C0.67660.55710.11470.088*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Pd10.03735 (16)0.03482 (16)0.03421 (16)0.00236 (10)0.00149 (10)0.00492 (10)
Br10.0765 (3)0.0515 (2)0.0634 (3)0.0026 (2)0.0009 (2)0.0195 (2)
O10.0782 (19)0.0491 (15)0.0652 (17)0.0235 (14)0.0259 (15)0.0074 (13)
O20.0477 (12)0.0354 (11)0.0450 (12)0.0084 (9)0.0083 (10)0.0061 (9)
O30.0664 (16)0.0390 (13)0.0692 (17)0.0145 (11)0.0214 (13)0.0205 (12)
O40.0478 (12)0.0430 (12)0.0422 (12)0.0101 (10)0.0083 (10)0.0052 (10)
O50.085 (2)0.0609 (17)0.0537 (16)0.0198 (15)0.0327 (14)0.0159 (13)
N10.0395 (14)0.0366 (14)0.0430 (15)0.0045 (11)0.0020 (11)0.0040 (11)
N20.0401 (14)0.0455 (15)0.0341 (13)0.0022 (11)0.0030 (11)0.0050 (11)
C10.137 (5)0.074 (3)0.105 (4)0.041 (3)0.041 (4)0.002 (3)
C20.099 (4)0.046 (2)0.097 (4)0.021 (2)0.031 (3)0.002 (2)
C30.0479 (17)0.0368 (16)0.0498 (19)0.0109 (13)0.0022 (15)0.0012 (14)
C40.0460 (17)0.0358 (16)0.0465 (18)0.0063 (13)0.0014 (14)0.0026 (13)
C50.0371 (15)0.0365 (15)0.0382 (16)0.0038 (12)0.0014 (12)0.0021 (12)
C60.0366 (15)0.0359 (15)0.0391 (16)0.0016 (12)0.0028 (13)0.0008 (12)
C70.0407 (16)0.0411 (17)0.0419 (17)0.0036 (13)0.0063 (13)0.0057 (13)
C80.0475 (18)0.0355 (16)0.0480 (19)0.0047 (13)0.0041 (15)0.0090 (14)
C90.0419 (16)0.0346 (15)0.0471 (18)0.0078 (13)0.0031 (14)0.0017 (13)
C100.0364 (15)0.0415 (16)0.0346 (16)0.0018 (12)0.0016 (12)0.0029 (13)
C110.0336 (14)0.0361 (15)0.0380 (16)0.0044 (11)0.0021 (12)0.0007 (12)
C120.0405 (16)0.0390 (16)0.0359 (16)0.0048 (12)0.0022 (13)0.0042 (12)
C130.0464 (18)0.053 (2)0.0333 (16)0.0022 (15)0.0019 (14)0.0073 (14)
C140.0500 (19)0.0526 (19)0.0363 (17)0.0082 (15)0.0096 (14)0.0059 (14)
C150.075 (3)0.076 (3)0.044 (2)0.017 (2)0.0166 (19)0.0172 (18)
C160.112 (4)0.081 (3)0.054 (3)0.005 (3)0.040 (3)0.011 (2)
C170.067 (2)0.047 (2)0.064 (2)0.0161 (18)0.003 (2)0.0165 (18)
Geometric parameters (Å, º) top
Pd1—C111.954 (3)C3—C41.328 (5)
Pd1—N12.056 (3)C4—H4A0.9300
Pd1—N22.055 (3)C5—C61.447 (4)
Pd1—Br12.4941 (4)C6—C111.371 (5)
O1—C31.326 (4)C6—C71.387 (4)
O1—C21.451 (5)C7—C81.378 (4)
O2—C51.344 (4)C7—H7A0.9300
O2—C31.378 (4)C8—C91.399 (5)
O3—C81.380 (4)C9—C101.392 (5)
O3—C171.425 (4)C9—H9A0.9300
O4—C121.342 (4)C10—C111.377 (4)
O4—C141.374 (4)C10—C121.438 (4)
O5—C141.323 (4)C13—C141.350 (5)
O5—C151.435 (5)C13—H13A0.9300
N1—C51.312 (4)C15—C161.475 (6)
N1—C41.400 (4)C15—H15A0.9700
N2—C121.325 (4)C15—H15B0.9700
N2—C131.380 (4)C16—H16A0.9600
C1—C21.492 (7)C16—H16B0.9600
C1—H1A0.9600C16—H16C0.9600
C1—H1B0.9600C17—H17A0.9600
C1—H1C0.9600C17—H17B0.9600
C2—H2A0.9700C17—H17C0.9600
C2—H2B0.9700
C11—Pd1—N279.26 (12)C8—C7—H7A120.6
C11—Pd1—N179.31 (11)C6—C7—H7A120.6
N2—Pd1—N1158.57 (11)C7—C8—O3115.2 (3)
C11—Pd1—Br1179.10 (9)C7—C8—C9122.1 (3)
N2—Pd1—Br1100.00 (8)O3—C8—C9122.7 (3)
N1—Pd1—Br1101.42 (7)C10—C9—C8117.5 (3)
C3—O1—C2114.6 (3)C10—C9—H9A121.3
C5—O2—C3104.3 (2)C8—C9—H9A121.3
C8—O3—C17118.0 (3)C11—C10—C9120.4 (3)
C12—O4—C14104.9 (2)C11—C10—C12109.2 (3)
C14—O5—C15116.3 (3)C9—C10—C12130.4 (3)
C5—N1—C4106.2 (3)C6—C11—C10121.2 (3)
C5—N1—Pd1112.1 (2)C6—C11—Pd1119.3 (2)
C4—N1—Pd1141.7 (2)C10—C11—Pd1119.5 (2)
C12—N2—C13107.0 (3)N2—C12—O4111.8 (3)
C12—N2—Pd1112.0 (2)N2—C12—C10120.0 (3)
C13—N2—Pd1141.0 (2)O4—C12—C10128.2 (3)
C2—C1—H1A109.5C14—C13—N2106.6 (3)
C2—C1—H1B109.5C14—C13—H13A126.7
H1A—C1—H1B109.5N2—C13—H13A126.7
C2—C1—H1C109.5O5—C14—C13137.7 (3)
H1A—C1—H1C109.5O5—C14—O4112.5 (3)
H1B—C1—H1C109.5C13—C14—O4109.7 (3)
O1—C2—C1107.5 (4)O5—C15—C16107.2 (4)
O1—C2—H2A110.2O5—C15—H15A110.3
C1—C2—H2A110.2C16—C15—H15A110.3
O1—C2—H2B110.2O5—C15—H15B110.3
C1—C2—H2B110.2C16—C15—H15B110.3
H2A—C2—H2B108.5H15A—C15—H15B108.5
O1—C3—C4138.5 (3)C15—C16—H16A109.5
O1—C3—O2111.2 (3)C15—C16—H16B109.5
C4—C3—O2110.2 (3)H16A—C16—H16B109.5
C3—C4—N1106.7 (3)C15—C16—H16C109.5
C3—C4—H4A126.6H16A—C16—H16C109.5
N1—C4—H4A126.6H16B—C16—H16C109.5
N1—C5—O2112.5 (3)O3—C17—H17A109.5
N1—C5—C6120.1 (3)O3—C17—H17B109.5
O2—C5—C6127.3 (3)H17A—C17—H17B109.5
C11—C6—C7119.9 (3)O3—C17—H17C109.5
C11—C6—C5109.2 (3)H17A—C17—H17C109.5
C7—C6—C5130.9 (3)H17B—C17—H17C109.5
C8—C7—C6118.9 (3)
C11—Pd1—N1—C51.0 (2)C17—O3—C8—C913.7 (5)
N2—Pd1—N1—C51.9 (4)C7—C8—C9—C100.8 (5)
Br1—Pd1—N1—C5179.6 (2)O3—C8—C9—C10179.9 (3)
C11—Pd1—N1—C4178.5 (4)C8—C9—C10—C111.1 (5)
N2—Pd1—N1—C4177.5 (3)C8—C9—C10—C12179.5 (3)
Br1—Pd1—N1—C41.0 (4)C7—C6—C11—C100.7 (5)
C11—Pd1—N2—C120.9 (2)C5—C6—C11—C10178.7 (3)
N1—Pd1—N2—C120.1 (4)C7—C6—C11—Pd1178.6 (2)
Br1—Pd1—N2—C12178.6 (2)C5—C6—C11—Pd10.6 (4)
C11—Pd1—N2—C13179.9 (4)C9—C10—C11—C61.9 (5)
N1—Pd1—N2—C13179.2 (3)C12—C10—C11—C6179.4 (3)
Br1—Pd1—N2—C130.6 (4)C9—C10—C11—Pd1177.5 (2)
C3—O1—C2—C1179.3 (4)C12—C10—C11—Pd11.3 (4)
C2—O1—C3—C46.5 (7)N2—Pd1—C11—C6179.4 (3)
C2—O1—C3—O2173.7 (4)N1—Pd1—C11—C60.9 (2)
C5—O2—C3—O1179.6 (3)N2—Pd1—C11—C101.2 (2)
C5—O2—C3—C40.3 (4)N1—Pd1—C11—C10178.5 (3)
O1—C3—C4—N1179.9 (4)C13—N2—C12—O40.7 (4)
O2—C3—C4—N10.2 (4)Pd1—N2—C12—O4179.8 (2)
C5—N1—C4—C30.6 (4)C13—N2—C12—C10180.0 (3)
Pd1—N1—C4—C3178.8 (3)Pd1—N2—C12—C100.5 (4)
C4—N1—C5—O20.9 (3)C14—O4—C12—N20.8 (4)
Pd1—N1—C5—O2178.8 (2)C14—O4—C12—C10180.0 (3)
C4—N1—C5—C6178.7 (3)C11—C10—C12—N20.5 (4)
Pd1—N1—C5—C61.0 (4)C9—C10—C12—N2178.1 (3)
C3—O2—C5—N10.7 (4)C11—C10—C12—O4178.8 (3)
C3—O2—C5—C6178.3 (3)C9—C10—C12—O42.7 (6)
N1—C5—C6—C110.3 (4)C12—N2—C13—C140.3 (4)
O2—C5—C6—C11177.7 (3)Pd1—N2—C13—C14179.6 (3)
N1—C5—C6—C7177.4 (3)C15—O5—C14—C135.6 (7)
O2—C5—C6—C70.0 (6)C15—O5—C14—O4176.2 (3)
C11—C6—C7—C81.2 (5)N2—C13—C14—O5178.1 (4)
C5—C6—C7—C8176.3 (3)N2—C13—C14—O40.1 (4)
C6—C7—C8—O3178.8 (3)C12—O4—C14—O5178.2 (3)
C6—C7—C8—C92.0 (5)C12—O4—C14—C130.5 (4)
C17—O3—C8—C7167.0 (3)C14—O5—C15—C16175.5 (4)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C2—H2A···Br1i0.972.803.526 (5)132
C16—H16A···O2ii0.962.443.391 (5)170
Symmetry codes: (i) x+2, y+1, z; (ii) x1, y, z+1.
Selected bond lengths (Å) top
Pd1—C111.954 (3)Pd1—N22.055 (3)
Pd1—N12.056 (3)Pd1—Br12.4941 (4)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C2—H2A···Br1i0.972.803.526 (5)132
C16—H16A···O2ii0.962.443.391 (5)170
Symmetry codes: (i) x+2, y+1, z; (ii) x1, y, z+1.
Acknowledgements top

The authors appreciate financial support from the National Natural Science Foundation of China (grant No. 20971105) and the Fundamental Research Funds for the Central Universities (grant No. XDJK2012B011).

references
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