Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270102011988/ln1140sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270102011988/ln1140Isup2.hkl |
CCDC reference: 193408
The title complex was prepared by the direct reaction of zinc(II) bromide with a stoichiometric amount of (-)-sparteine in an ethanol–triethylorthoformate (5:1 v/v) solution. The resulting colorless precipitate was filtered off, washed with cold absolute ethanol and dried under vacuum. Single crystals of (I) were obtained by recrystallization at room temperature from a dichloromethane–triethylorthoformate (4:1 v/v) solution under carbon tetrachloride vapor.
The absolute configuration was confirmed crystallographically to agree with that expected for (-)-sparteine. The positional parameters of the H atoms were calculated geometrically (C—H = 0.97–0.98 Å) and constrained to ride on their parent atoms, with Uiso(H) = 1.2Ueq(C).
Data collection: CAD-4 EXPRESS (Enraf-Nonius, 1994); cell refinement: CAD-4 EXPRESS; data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
Fig. 1. A view of the molecule of (I), showing the atom-numbering scheme and 30% probability displacement ellipsoids. H atoms have been omitted for clarity. |
[ZnBr2(C15H26N2)] | F(000) = 920 |
Mr = 459.57 | Dx = 1.779 Mg m−3 |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 25 reflections |
a = 11.1770 (14) Å | θ = 11.4–12.6° |
b = 12.0378 (18) Å | µ = 6.08 mm−1 |
c = 12.7533 (9) Å | T = 293 K |
V = 1715.9 (4) Å3 | Block, colorless |
Z = 4 | 0.40 × 0.33 × 0.3 mm |
Enraf-Nonius CAD-4 diffractometer | 2729 reflections with I > 2σ(I) |
Radiation source: fine-focus sealed tube | Rint = 0.029 |
Graphite monochromator | θmax = 27.5°, θmin = 2.3° |
Non–profiled ω/2θ scans | h = −14→14 |
Absorption correction: ψ scan (North et al., 1968) | k = −15→15 |
Tmin = 0.104, Tmax = 0.161 | l = −16→16 |
4912 measured reflections | 3 standard reflections every 300 min |
3928 independent reflections | intensity decay: 1% |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.053 | H-atom parameters constrained |
wR(F2) = 0.104 | w = 1/[σ2(Fo2) + (0.0474P)2] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max < 0.001 |
3928 reflections | Δρmax = 0.69 e Å−3 |
181 parameters | Δρmin = −0.57 e Å−3 |
0 restraints | Absolute structure: Flack (1983), 1689 Friedel pairs |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: −0.02 (2) |
[ZnBr2(C15H26N2)] | V = 1715.9 (4) Å3 |
Mr = 459.57 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 11.1770 (14) Å | µ = 6.08 mm−1 |
b = 12.0378 (18) Å | T = 293 K |
c = 12.7533 (9) Å | 0.40 × 0.33 × 0.3 mm |
Enraf-Nonius CAD-4 diffractometer | 2729 reflections with I > 2σ(I) |
Absorption correction: ψ scan (North et al., 1968) | Rint = 0.029 |
Tmin = 0.104, Tmax = 0.161 | 3 standard reflections every 300 min |
4912 measured reflections | intensity decay: 1% |
3928 independent reflections |
R[F2 > 2σ(F2)] = 0.053 | H-atom parameters constrained |
wR(F2) = 0.104 | Δρmax = 0.69 e Å−3 |
S = 1.03 | Δρmin = −0.57 e Å−3 |
3928 reflections | Absolute structure: Flack (1983), 1689 Friedel pairs |
181 parameters | Absolute structure parameter: −0.02 (2) |
0 restraints |
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 | ||
Zn | 0.19451 (7) | 0.26450 (6) | 0.13204 (5) | 0.02983 (19) | |
Br1 | 0.17519 (9) | 0.43930 (6) | 0.04949 (6) | 0.0565 (3) | |
Br2 | 0.21351 (8) | 0.11392 (6) | 0.01497 (5) | 0.0497 (2) | |
N1 | 0.3049 (5) | 0.2867 (4) | 0.2622 (4) | 0.0300 (12) | |
N9 | 0.0535 (5) | 0.2301 (4) | 0.2331 (4) | 0.0274 (12) | |
C2 | 0.4264 (7) | 0.3199 (6) | 0.2286 (6) | 0.0420 (18) | |
H2A | 0.4735 | 0.3389 | 0.2899 | 0.050* | |
H2B | 0.4209 | 0.3855 | 0.1847 | 0.050* | |
C3 | 0.4885 (7) | 0.2295 (6) | 0.1692 (6) | 0.0476 (19) | |
H3A | 0.5684 | 0.2537 | 0.1503 | 0.057* | |
H3B | 0.4450 | 0.2139 | 0.1051 | 0.057* | |
C4 | 0.4963 (8) | 0.1251 (8) | 0.2349 (7) | 0.059 (2) | |
H4A | 0.5480 | 0.1383 | 0.2947 | 0.071* | |
H4B | 0.5310 | 0.0657 | 0.1935 | 0.071* | |
C5 | 0.3726 (6) | 0.0905 (6) | 0.2730 (6) | 0.046 (2) | |
H5A | 0.3238 | 0.0685 | 0.2136 | 0.056* | |
H5B | 0.3798 | 0.0271 | 0.3196 | 0.056* | |
C6 | 0.3126 (6) | 0.1857 (5) | 0.3305 (5) | 0.0341 (15) | |
H6 | 0.3646 | 0.2050 | 0.3896 | 0.041* | |
C7 | 0.1884 (6) | 0.1586 (6) | 0.3770 (5) | 0.0434 (18) | |
H7 | 0.1977 | 0.0931 | 0.4219 | 0.052* | |
C8 | 0.1319 (6) | 0.3534 (6) | 0.3736 (5) | 0.0393 (17) | |
H8 | 0.1094 | 0.4173 | 0.4170 | 0.047* | |
C10 | −0.0510 (6) | 0.2026 (6) | 0.1650 (5) | 0.0387 (17) | |
H10A | −0.0359 | 0.1318 | 0.1311 | 0.046* | |
H10B | −0.0571 | 0.2585 | 0.1105 | 0.046* | |
C11 | −0.1696 (7) | 0.1959 (6) | 0.2217 (6) | 0.047 (2) | |
H11A | −0.1676 | 0.1354 | 0.2719 | 0.057* | |
H11B | −0.2329 | 0.1808 | 0.1716 | 0.057* | |
C12 | −0.1953 (7) | 0.3039 (6) | 0.2782 (5) | 0.0492 (19) | |
H12A | −0.2697 | 0.2980 | 0.3170 | 0.059* | |
H12B | −0.2031 | 0.3640 | 0.2279 | 0.059* | |
C13 | −0.0924 (6) | 0.3277 (6) | 0.3529 (5) | 0.0423 (18) | |
H13A | −0.1064 | 0.3983 | 0.3874 | 0.051* | |
H13B | −0.0904 | 0.2705 | 0.4065 | 0.051* | |
C14 | 0.0284 (6) | 0.3315 (5) | 0.2980 (5) | 0.0302 (15) | |
H14 | 0.0257 | 0.3945 | 0.2495 | 0.036* | |
C15 | 0.2515 (6) | 0.3803 (6) | 0.3236 (5) | 0.0440 (18) | |
H15A | 0.2413 | 0.4436 | 0.2775 | 0.053* | |
H15B | 0.3072 | 0.4017 | 0.3783 | 0.053* | |
C16 | 0.0901 (6) | 0.1332 (6) | 0.2990 (5) | 0.0374 (17) | |
H16A | 0.1169 | 0.0739 | 0.2531 | 0.045* | |
H16B | 0.0207 | 0.1064 | 0.3369 | 0.045* | |
C17 | 0.1478 (7) | 0.2547 (7) | 0.4468 (5) | 0.050 (2) | |
H17A | 0.0729 | 0.2367 | 0.4814 | 0.060* | |
H17B | 0.2075 | 0.2707 | 0.4999 | 0.060* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Zn | 0.0384 (4) | 0.0290 (4) | 0.0220 (3) | −0.0004 (4) | 0.0036 (4) | 0.0003 (3) |
Br1 | 0.0905 (7) | 0.0407 (4) | 0.0384 (4) | 0.0056 (5) | 0.0078 (4) | 0.0154 (3) |
Br2 | 0.0707 (6) | 0.0437 (4) | 0.0347 (4) | 0.0057 (4) | 0.0059 (4) | −0.0119 (3) |
N1 | 0.030 (3) | 0.031 (3) | 0.029 (3) | −0.005 (3) | 0.003 (3) | 0.000 (2) |
N9 | 0.028 (3) | 0.028 (3) | 0.026 (3) | 0.002 (3) | 0.001 (2) | −0.004 (2) |
C2 | 0.034 (4) | 0.042 (4) | 0.050 (5) | −0.007 (4) | −0.007 (4) | 0.011 (4) |
C3 | 0.033 (4) | 0.060 (5) | 0.050 (4) | 0.001 (4) | 0.006 (4) | 0.008 (4) |
C4 | 0.044 (5) | 0.061 (5) | 0.071 (6) | 0.014 (5) | 0.012 (4) | 0.017 (5) |
C5 | 0.038 (4) | 0.053 (5) | 0.049 (4) | 0.009 (4) | 0.005 (4) | 0.016 (4) |
C6 | 0.031 (4) | 0.044 (4) | 0.028 (3) | −0.002 (4) | −0.006 (3) | 0.008 (3) |
C7 | 0.042 (4) | 0.052 (4) | 0.036 (3) | 0.009 (4) | −0.003 (4) | 0.022 (3) |
C8 | 0.044 (4) | 0.048 (4) | 0.026 (3) | 0.004 (4) | 0.001 (3) | −0.012 (3) |
C10 | 0.030 (4) | 0.044 (4) | 0.042 (4) | 0.001 (3) | −0.008 (3) | −0.011 (3) |
C11 | 0.032 (5) | 0.055 (5) | 0.055 (5) | −0.005 (4) | −0.007 (4) | 0.005 (4) |
C12 | 0.038 (5) | 0.065 (5) | 0.044 (4) | 0.018 (4) | 0.006 (4) | 0.011 (4) |
C13 | 0.040 (4) | 0.055 (5) | 0.032 (4) | 0.018 (4) | 0.008 (3) | −0.001 (3) |
C14 | 0.033 (4) | 0.029 (4) | 0.028 (3) | 0.003 (3) | 0.000 (3) | 0.000 (3) |
C15 | 0.047 (5) | 0.044 (4) | 0.041 (4) | 0.001 (4) | −0.002 (3) | −0.014 (4) |
C16 | 0.031 (4) | 0.036 (4) | 0.046 (4) | 0.003 (3) | 0.007 (3) | 0.015 (3) |
C17 | 0.045 (4) | 0.079 (6) | 0.026 (3) | 0.017 (4) | 0.000 (3) | −0.001 (4) |
Zn—N9 | 2.078 (5) | C7—C17 | 1.529 (10) |
Zn—N1 | 2.086 (5) | C7—H7 | 0.9800 |
Zn—Br2 | 2.3580 (10) | C8—C15 | 1.515 (9) |
Zn—Br1 | 2.3628 (10) | C8—C17 | 1.521 (9) |
N1—C2 | 1.478 (9) | C8—C14 | 1.530 (9) |
N1—C15 | 1.496 (8) | C8—H8 | 0.9800 |
N1—C6 | 1.499 (7) | C10—C11 | 1.512 (10) |
N9—C10 | 1.492 (8) | C10—H10A | 0.9700 |
N9—C16 | 1.495 (8) | C10—H10B | 0.9700 |
N9—C14 | 1.500 (8) | C11—C12 | 1.515 (10) |
C2—C3 | 1.497 (10) | C11—H11A | 0.9700 |
C2—H2A | 0.9700 | C11—H11B | 0.9700 |
C2—H2B | 0.9700 | C12—C13 | 1.521 (10) |
C3—C4 | 1.512 (10) | C12—H12A | 0.9700 |
C3—H3A | 0.9700 | C12—H12B | 0.9700 |
C3—H3B | 0.9700 | C13—C14 | 1.521 (9) |
C4—C5 | 1.525 (11) | C13—H13A | 0.9700 |
C4—H4A | 0.9700 | C13—H13B | 0.9700 |
C4—H4B | 0.9700 | C14—H14 | 0.9800 |
C5—C6 | 1.517 (9) | C15—H15A | 0.9700 |
C5—H5A | 0.9700 | C15—H15B | 0.9700 |
C5—H5B | 0.9700 | C16—H16A | 0.9700 |
C6—C7 | 1.544 (9) | C16—H16B | 0.9700 |
C6—H6 | 0.9800 | C17—H17A | 0.9700 |
C7—C16 | 1.513 (10) | C17—H17B | 0.9700 |
N9—Zn—N1 | 88.9 (2) | C15—C8—C17 | 108.8 (6) |
N9—Zn—Br2 | 107.95 (14) | C15—C8—C14 | 116.0 (5) |
N1—Zn—Br2 | 123.31 (14) | C17—C8—C14 | 109.9 (6) |
N9—Zn—Br1 | 112.60 (14) | C15—C8—H8 | 107.2 |
N1—Zn—Br1 | 107.12 (13) | C17—C8—H8 | 107.2 |
Br2—Zn—Br1 | 114.25 (4) | C14—C8—H8 | 107.2 |
C2—N1—C15 | 108.4 (5) | N9—C10—C11 | 114.8 (6) |
C2—N1—C6 | 109.6 (5) | N9—C10—H10A | 108.6 |
C15—N1—C6 | 109.2 (5) | C11—C10—H10A | 108.6 |
C2—N1—Zn | 110.4 (4) | N9—C10—H10B | 108.6 |
C15—N1—Zn | 106.1 (4) | C11—C10—H10B | 108.6 |
C6—N1—Zn | 113.1 (4) | H10A—C10—H10B | 107.5 |
C10—N9—C16 | 111.6 (5) | C10—C11—C12 | 110.3 (6) |
C10—N9—C14 | 110.8 (5) | C10—C11—H11A | 109.6 |
C16—N9—C14 | 112.1 (5) | C12—C11—H11A | 109.6 |
C10—N9—Zn | 106.1 (4) | C10—C11—H11B | 109.6 |
C16—N9—Zn | 107.2 (4) | C12—C11—H11B | 109.6 |
C14—N9—Zn | 108.8 (4) | H11A—C11—H11B | 108.1 |
N1—C2—C3 | 112.1 (6) | C11—C12—C13 | 108.4 (6) |
N1—C2—H2A | 109.2 | C11—C12—H12A | 110.0 |
C3—C2—H2A | 109.2 | C13—C12—H12A | 110.0 |
N1—C2—H2B | 109.2 | C11—C12—H12B | 110.0 |
C3—C2—H2B | 109.2 | C13—C12—H12B | 110.0 |
H2A—C2—H2B | 107.9 | H12A—C12—H12B | 108.4 |
C2—C3—C4 | 110.5 (6) | C12—C13—C14 | 112.8 (5) |
C2—C3—H3A | 109.6 | C12—C13—H13A | 109.0 |
C4—C3—H3A | 109.6 | C14—C13—H13A | 109.0 |
C2—C3—H3B | 109.6 | C12—C13—H13B | 109.0 |
C4—C3—H3B | 109.6 | C14—C13—H13B | 109.0 |
H3A—C3—H3B | 108.1 | H13A—C13—H13B | 107.8 |
C3—C4—C5 | 110.6 (6) | N9—C14—C13 | 113.3 (6) |
C3—C4—H4A | 109.5 | N9—C14—C8 | 110.3 (5) |
C5—C4—H4A | 109.5 | C13—C14—C8 | 112.7 (5) |
C3—C4—H4B | 109.5 | N9—C14—H14 | 106.7 |
C5—C4—H4B | 109.5 | C13—C14—H14 | 106.7 |
H4A—C4—H4B | 108.1 | C8—C14—H14 | 106.7 |
C6—C5—C4 | 110.4 (7) | N1—C15—C8 | 114.3 (6) |
C6—C5—H5A | 109.6 | N1—C15—H15A | 108.7 |
C4—C5—H5A | 109.6 | C8—C15—H15A | 108.7 |
C6—C5—H5B | 109.6 | N1—C15—H15B | 108.7 |
C4—C5—H5B | 109.6 | C8—C15—H15B | 108.7 |
H5A—C5—H5B | 108.1 | H15A—C15—H15B | 107.6 |
N1—C6—C5 | 110.9 (5) | N9—C16—C7 | 114.2 (6) |
N1—C6—C7 | 110.1 (5) | N9—C16—H16A | 108.7 |
C5—C6—C7 | 115.0 (6) | C7—C16—H16A | 108.7 |
N1—C6—H6 | 106.8 | N9—C16—H16B | 108.7 |
C5—C6—H6 | 106.8 | C7—C16—H16B | 108.7 |
C7—C6—H6 | 106.8 | H16A—C16—H16B | 107.6 |
C16—C7—C17 | 108.7 (6) | C8—C17—C7 | 105.5 (5) |
C16—C7—C6 | 116.3 (6) | C8—C17—H17A | 110.6 |
C17—C7—C6 | 109.3 (6) | C7—C17—H17A | 110.6 |
C16—C7—H7 | 107.4 | C8—C17—H17B | 110.6 |
C17—C7—H7 | 107.4 | C7—C17—H17B | 110.6 |
C6—C7—H7 | 107.4 | H17A—C17—H17B | 108.8 |
N9—Zn—N1—C2 | −177.7 (4) | N1—C6—C7—C17 | −62.8 (6) |
Br2—Zn—N1—C2 | 71.4 (4) | C5—C6—C7—C17 | 171.0 (5) |
Br1—Zn—N1—C2 | −64.4 (4) | C16—N9—C10—C11 | 74.6 (7) |
N9—Zn—N1—C15 | −60.5 (4) | C14—N9—C10—C11 | −51.1 (8) |
Br2—Zn—N1—C15 | −171.4 (3) | Zn—N9—C10—C11 | −169.0 (5) |
Br1—Zn—N1—C15 | 52.8 (4) | N9—C10—C11—C12 | 56.9 (8) |
N9—Zn—N1—C6 | 59.2 (4) | C10—C11—C12—C13 | −57.1 (7) |
Br2—Zn—N1—C6 | −51.7 (5) | C11—C12—C13—C14 | 56.4 (8) |
Br1—Zn—N1—C6 | 172.5 (4) | C10—N9—C14—C13 | 48.1 (7) |
N1—Zn—N9—C10 | −177.5 (4) | C16—N9—C14—C13 | −77.3 (6) |
Br2—Zn—N9—C10 | −52.7 (4) | Zn—N9—C14—C13 | 164.4 (4) |
Br1—Zn—N9—C10 | 74.4 (4) | C10—N9—C14—C8 | 175.5 (5) |
N1—Zn—N9—C16 | −58.2 (4) | C16—N9—C14—C8 | 50.1 (7) |
Br2—Zn—N9—C16 | 66.6 (4) | Zn—N9—C14—C8 | −68.3 (5) |
Br1—Zn—N9—C16 | −166.3 (3) | C12—C13—C14—N9 | −53.0 (8) |
N1—Zn—N9—C14 | 63.2 (4) | C12—C13—C14—C8 | −179.0 (6) |
Br2—Zn—N9—C14 | −171.9 (3) | C15—C8—C14—N9 | 63.6 (8) |
Br1—Zn—N9—C14 | −44.9 (4) | C17—C8—C14—N9 | −60.4 (7) |
C15—N1—C2—C3 | 178.2 (6) | C15—C8—C14—C13 | −168.7 (6) |
C6—N1—C2—C3 | 59.1 (7) | C17—C8—C14—C13 | 67.3 (7) |
Zn—N1—C2—C3 | −66.0 (6) | C2—N1—C15—C8 | −173.5 (6) |
N1—C2—C3—C4 | −57.7 (9) | C6—N1—C15—C8 | −54.2 (7) |
C2—C3—C4—C5 | 54.7 (9) | Zn—N1—C15—C8 | 68.0 (6) |
C3—C4—C5—C6 | −54.6 (9) | C17—C8—C15—N1 | 58.9 (7) |
C2—N1—C6—C5 | −58.4 (7) | C14—C8—C15—N1 | −65.6 (8) |
C15—N1—C6—C5 | −176.9 (5) | C10—N9—C16—C7 | −174.7 (5) |
Zn—N1—C6—C5 | 65.2 (6) | C14—N9—C16—C7 | −49.8 (7) |
C2—N1—C6—C7 | 173.2 (5) | Zn—N9—C16—C7 | 69.5 (6) |
C15—N1—C6—C7 | 54.6 (7) | C17—C7—C16—N9 | 56.5 (7) |
Zn—N1—C6—C7 | −63.3 (6) | C6—C7—C16—N9 | −67.3 (8) |
C4—C5—C6—N1 | 56.7 (8) | C15—C8—C17—C7 | −61.7 (7) |
C4—C5—C6—C7 | −177.5 (6) | C14—C8—C17—C7 | 66.3 (7) |
N1—C6—C7—C16 | 60.7 (8) | C16—C7—C17—C8 | −62.9 (7) |
C5—C6—C7—C16 | −65.5 (7) | C6—C7—C17—C8 | 65.0 (7) |
Experimental details
Crystal data | |
Chemical formula | [ZnBr2(C15H26N2)] |
Mr | 459.57 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 293 |
a, b, c (Å) | 11.1770 (14), 12.0378 (18), 12.7533 (9) |
V (Å3) | 1715.9 (4) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 6.08 |
Crystal size (mm) | 0.40 × 0.33 × 0.3 |
Data collection | |
Diffractometer | Enraf-Nonius CAD-4 diffractometer |
Absorption correction | ψ scan (North et al., 1968) |
Tmin, Tmax | 0.104, 0.161 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 4912, 3928, 2729 |
Rint | 0.029 |
(sin θ/λ)max (Å−1) | 0.649 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.053, 0.104, 1.03 |
No. of reflections | 3928 |
No. of parameters | 181 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.69, −0.57 |
Absolute structure | Flack (1983), 1689 Friedel pairs |
Absolute structure parameter | −0.02 (2) |
Computer programs: CAD-4 EXPRESS (Enraf-Nonius, 1994), CAD-4 EXPRESS, XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 for Windows (Farrugia, 1997), WinGX (Farrugia, 1999).
Zn—N9 | 2.078 (5) | Zn—Br2 | 2.3580 (10) |
Zn—N1 | 2.086 (5) | Zn—Br1 | 2.3628 (10) |
N9—Zn—N1 | 88.9 (2) | N9—Zn—Br1 | 112.60 (14) |
N9—Zn—Br2 | 107.95 (14) | N1—Zn—Br1 | 107.12 (13) |
N1—Zn—Br2 | 123.31 (14) | Br2—Zn—Br1 | 114.25 (4) |
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Many structural studies of transition metal(II) complexes with (-)-sparteine have been reported (Choi et al., 1995; Kim et al., 2001; Kuroda & Mason, 1979; Lee et al., 2000; Lopez et al., 1998), but, to date, relatively little is known about the structural characteristics of the corresponding ZnII complexes. The crystal structure of a 1:1 adduct of dimethylzinc and (-)-sparteine is a rare example (Motevalli et al., 1993). Like other four-coordinate (-)-sparteine–copper(II) complexes, this adduct is monomeric with pseudo-tetrahedral coordination at the metal center, and the N—Zn—N bond angle of 80.4 (2)° is the smallest among the N—M—N angles found in four-coordinate (-)-sparteine–metal(II) complexes (Choi et al., 1995; Kim et al., 2001; Kuroda & Mason, 1979; Lee et al., 2000; Lopez et al., 1998). The title ZnII complex, (I), was prepared and its crystal structure determined in order to evaluate the steric effects imposed by a bulky (-)-sparteine ligand and to recognize the role of the coordinating anionic ligands and the metal ions in these complexes. It is well known that the crystal-field stabilization effect favors a square-planar coordination geometry for four-coordinate CuII complexes (Figgis, 1966). However, due to the closed-shell electronic structure of ZnII, the coordination geometry around the ZnII center in (I) will be determined solely by the steric effects of the coordinating ligands, and the dihedral angle between the N—Zn—N and Br—Zn—Br planes is expected to be larger than those observed in the (-)-sparteine–copper(II) complexes.
All four of the six-membered rings in the (-)-l-sparteine moiety, which is one of three sparteine diastereoismers, are in the chair conformation. The conformation of the coordinated (-)-sparteine ligand in (I) consists of one terminal ring folded down over the metal (endo) and another terminal ring folded back away from the metal (exo), identical to the conformation of the free ligand (Boschmann et al., 1974; Wrobleski & Long, 1977). The coordination geometry around the metal center in the known four-coordinate (-)-sparteine–metal(II) complexes is a distorted tetrahedron (Choi et al., 1995; Kim et al., 2001; Kuroda & Mason, 1979; Lee et al., 2000; Lopez et al., 1998). The dihedral angles between the N—Cu—N and X—Cu—X (X = Cl or O) planes in [CuCl2(C15H26N2)], [Cu(NO3)2(C15H26N2)] and [Cu(C2H3O2)2(C15H26N2)] were found to be 67.0, 31.7 and 45.8°, respectively (Choi et al., 1995; Lopez et al., 1998; Lee et al., 2000). The dihedral angle between the N1—Zn—N9 and Br1—Zn—Br2 planes in (I) is 82.4 (1)°, so that the geometry around the ZnII center is almost an ideal tetrahedron. The smaller dihedral angle of 67.0° reported for the corresponding copper(II) dichloride complex can be visualized as a balance between the crystal-field stabilization effect and the steric effect of (-)-sparteine.
Another parameter associated with the distortion of the tetrahedron is the `tilt' of the bidentate (-)-sparteine ligand with respect to the Br1—Zn—Br2 plane. The midpoint of the N1···N9 line does not lie on the Br1—Zn—Br2 plane, but is tilted towards atom N1 by 0.164 Å (11.2% of half of the N1···N9 distance). Similarly, the midpoint of the Br1···Br2 line is tilted towards atom Br2 by 0.117 Å (5.9% of half of the Br1···Br2 distance). The N1—Zn—Br1 and N9—Zn—Br2 angles are quite similar. However, the N1—Zn—Br2 and N9—Zn—Br1 angles differ by more than 10°. These results clearly indicate that the reduction of the dihedral angles by about 8° from the perfect tetrahedral value of 90° in (I) is caused by intramolecular steric interactions between the (-)-sparteine moiety and the bromide ions coordinated to the ZnII atom.
The ZnII—N bond lengths in (I) (Table 1) are significantly shorter than those found in [Zn(CH3)2(C15H26N2)] [2.222 (5) and 2.256 (6) Å; Motevalli et al., 1993] and, consequently, the N—Zn—N bite angle in (I) is larger than the corresponding bite angle of 80.4 (2)° found in the dimethylzinc(II) complex. This result strongly suggests that the nature of the coordinating anions in (-)-sparteine–zinc(II) complexes plays an important role in the ultimate molecular structure of the complexes. The smaller N—Zn—N bite angle and the longer Zn—N bond distances found in [Zn(CH3)2(C15H26N2)] can be attributed to the presence of the coordinating methyl ligand, which is a very strong Lewis base and has a small C-donor atom. The average Zn—C bond distance [2.012 (8) Å] in [Zn(CH3)2(C15H26N2)] is about 0.35 Å shorter than the average Zn—Br bond distance in (I). Assuming that the steric demands of the methyl group and the bromide anion are similar, the elongation of the Zn—N bond distances in the (-)-sparteine–dimethylzinc(II) complex is probably caused by the reduction in the Lewis acidity of ZnII upon formation of strong Zn—C bonds.