Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536802016045/cf6198sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536802016045/cf6198Isup2.hkl |
CCDC reference: 198948
Key indicators
- Single-crystal X-ray study
- T = 173 K
- Mean (C-C) = 0.006 Å
- R factor = 0.059
- wR factor = 0.119
- Data-to-parameter ratio = 7.6
checkCIF results
No syntax errors found ADDSYM reports no extra symmetry
Alert Level C:
PLAT_420 Alert C D-H Without Acceptor N(3) - H(4) ? PLAT_420 Alert C D-H Without Acceptor N(4) - H(6) ? General Notes
REFLT_03 From the CIF: _diffrn_reflns_theta_max 25.01 From the CIF: _reflns_number_total 1773 Count of symmetry unique reflns 1777 Completeness (_total/calc) 99.77% TEST3: Check Friedels for noncentro structure Estimate of Friedel pairs measured 0 Fraction of Friedel pairs measured 0.000 Are heavy atom types Z>Si present no Please check that the estimate of the number of Friedel pairs is correct. If it is not, please give the correct count in the _publ_section_exptl_refinement section of the submitted CIF.
0 Alert Level A = Potentially serious problem
0 Alert Level B = Potential problem
2 Alert Level C = Please check
Distilled water was added dropwise to a stirred solution of Li2[(1R,2R)-(-)-1,2-{NC(Ph)N(SiMe3)}-C6H10] (synthesized according to Li, Weng, Wei & Liu, 2002) in hexane (in the mole ratio 4:1). After overnight reaction, the pale yellow mixture was filtered, then the solvent was removed in vacuum and the residual solid was redissolved in chloroform. After filtration, the filtrate was left at room temperature and colorless crystals of (I) grew at the bottom of the flask after 2 d. Elemental analysis and NMR spectra are completely in agreement with the structural composition of (I). Spectroscopic analysis: 1H NMR (CDCl3, δ, p.p.m.): 1.42 (d, 4H, CH), 1.78 (m, 2H, CH), 2.26 (m, 2H, CH), 3.97 (m, 2H, CH), 5.89 (s, 4H, NH), 7.35 (m, 3H, phenyl), 7.48 (m, 2H, phenyl); 13C NMR (CDCl3, δ, p.p.m.): 25.59, 32.98, 57.15, 126.98, 128.63, 129.22, 129.65, 131.24, 138.30, 169.33.
All H atoms were initially located in a difference Fourier map. The methyl H atoms were then constrained to an ideal geometry with C—H distances of 0.98 Å and Uiso(H) = 1.5Ueq(C), but each group was allowed to rotate freely about its C—C bond. The positions of the amine H atoms were refined freely along with isotropic displacement parameters. All other H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms with C—H distances in the range 0.95–1.00 Å and Uiso(H) = 1.2Ueq(C).
Anomalous dispersion effects are negligible, and Friedel pairs were merged in the refinement. The absolute configuration was assumed from the known (R,R) configuration of the starting lithium salt (Li, Weng, Wei & Liu, 2002). Furthermore, [(1R,2R)-(-)-1,2-(NSiMe3)2-C6H10]2Zr, derived from the same starting lithium salt, has been examined and its absolute configuration confirmed, with a Flack (1983) parameter of essentially zero (Li, Weng, Huang et al., 2002).
Data collection: SMART (Siemens, 1996); cell refinement: SAINT (Siemens, 1996); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.
Fig. 1. View of the molecule of (I), showing the atom-labeling scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented by small spheres of arbitrary radii. |
C20H24N4 | Dx = 1.234 Mg m−3 |
Mr = 320.43 | Mo Kα radiation, λ = 0.71073 Å |
Orthorhombic, P212121 | Cell parameters from 9871 reflections |
a = 8.696 (5) Å | θ = 2.5–19.5° |
b = 8.698 (5) Å | µ = 0.08 mm−1 |
c = 22.806 (13) Å | T = 173 K |
V = 1725.1 (17) Å3 | Block, colorless |
Z = 4 | 0.20 × 0.10 × 0.10 mm |
F(000) = 688 |
Siemens SMART CCD diffractometer | 1773 independent reflections |
Radiation source: fine-focus sealed tube | 1505 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.098 |
ω scans | θmax = 25.0°, θmin = 1.8° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −10→8 |
Tmin = 0.985, Tmax = 0.993 | k = −10→10 |
7152 measured reflections | l = −27→25 |
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)] = 0.059 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.119 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0443P)2] where P = (Fo2 + 2Fc2)/3 |
1773 reflections | (Δ/σ)max < 0.001 |
233 parameters | Δρmax = 0.19 e Å−3 |
0 restraints | Δρmin = −0.21 e Å−3 |
C20H24N4 | V = 1725.1 (17) Å3 |
Mr = 320.43 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 8.696 (5) Å | µ = 0.08 mm−1 |
b = 8.698 (5) Å | T = 173 K |
c = 22.806 (13) Å | 0.20 × 0.10 × 0.10 mm |
Siemens SMART CCD diffractometer | 1773 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1505 reflections with I > 2σ(I) |
Tmin = 0.985, Tmax = 0.993 | Rint = 0.098 |
7152 measured reflections |
R[F2 > 2σ(F2)] = 0.059 | 0 restraints |
wR(F2) = 0.119 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.06 | Δρmax = 0.19 e Å−3 |
1773 reflections | Δρmin = −0.21 e Å−3 |
233 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 | ||
C1 | 0.6641 (4) | 1.1146 (5) | −0.07579 (17) | 0.0281 (10) | |
H1A | 0.6654 | 1.2138 | −0.0952 | 0.034* | |
H1B | 0.7203 | 1.0422 | −0.1000 | 0.034* | |
C2 | 0.4994 (5) | 1.0606 (5) | −0.06898 (17) | 0.0296 (10) | |
H2A | 0.4535 | 1.0475 | −0.1074 | 0.036* | |
H2B | 0.4407 | 1.1379 | −0.0480 | 0.036* | |
C3 | 0.4926 (5) | 0.9086 (4) | −0.03554 (16) | 0.0262 (10) | |
H3A | 0.5409 | 0.8288 | −0.0588 | 0.031* | |
H3B | 0.3860 | 0.8800 | −0.0296 | 0.031* | |
C4 | 0.5733 (4) | 0.9190 (4) | 0.02394 (17) | 0.0245 (9) | |
H4A | 0.5186 | 0.9948 | 0.0479 | 0.029* | |
C5 | 0.7401 (4) | 0.9739 (4) | 0.01648 (16) | 0.0240 (9) | |
H5A | 0.7963 | 0.8976 | −0.0068 | 0.029* | |
C6 | 0.7416 (5) | 1.1278 (4) | −0.01648 (16) | 0.0260 (9) | |
H6A | 0.6890 | 1.2049 | 0.0068 | 0.031* | |
H6B | 0.8471 | 1.1612 | −0.0218 | 0.031* | |
C7 | 0.5489 (4) | 0.7581 (5) | 0.11289 (17) | 0.0258 (10) | |
C8 | 0.5178 (4) | 0.5991 (5) | 0.13581 (16) | 0.0247 (9) | |
C9 | 0.4193 (4) | 0.5804 (5) | 0.18368 (18) | 0.0289 (10) | |
H9A | 0.3752 | 0.6662 | 0.2013 | 0.035* | |
C10 | 0.3867 (5) | 0.4353 (5) | 0.20511 (18) | 0.0324 (11) | |
H10A | 0.3180 | 0.4235 | 0.2360 | 0.039* | |
C11 | 0.4564 (5) | 0.3077 (5) | 0.18059 (19) | 0.0362 (11) | |
H11A | 0.4358 | 0.2102 | 0.1954 | 0.043* | |
C12 | 0.5573 (5) | 0.3254 (5) | 0.13381 (18) | 0.0327 (11) | |
H12A | 0.6054 | 0.2398 | 0.1176 | 0.039* | |
C13 | 0.5862 (4) | 0.4699 (5) | 0.11131 (17) | 0.0267 (10) | |
H13A | 0.6521 | 0.4808 | 0.0795 | 0.032* | |
C14 | 0.9680 (4) | 0.9955 (4) | 0.08144 (17) | 0.0234 (9) | |
C15 | 1.0205 (4) | 1.0202 (4) | 0.14344 (16) | 0.0214 (9) | |
C16 | 1.1602 (4) | 0.9610 (5) | 0.16201 (17) | 0.0296 (10) | |
H16A | 1.2196 | 0.9029 | 0.1363 | 0.036* | |
C17 | 1.2127 (5) | 0.9880 (5) | 0.21909 (17) | 0.0315 (10) | |
H17A | 1.3063 | 0.9471 | 0.2311 | 0.038* | |
C18 | 1.1274 (5) | 1.0740 (5) | 0.25730 (19) | 0.0331 (11) | |
H18A | 1.1636 | 1.0926 | 0.2950 | 0.040* | |
C19 | 0.9872 (5) | 1.1334 (5) | 0.23974 (19) | 0.0392 (12) | |
H19A | 0.9283 | 1.1909 | 0.2658 | 0.047* | |
C20 | 0.9349 (4) | 1.1068 (5) | 0.18318 (18) | 0.0323 (10) | |
H20A | 0.8408 | 1.1475 | 0.1716 | 0.039* | |
N1 | 0.8139 (4) | 0.9876 (4) | 0.07407 (15) | 0.0254 (8) | |
N2 | 0.5649 (4) | 0.7690 (4) | 0.05406 (15) | 0.0256 (8) | |
N3 | 1.0598 (4) | 0.9847 (4) | 0.03657 (15) | 0.0275 (8) | |
N4 | 0.5610 (4) | 0.8788 (4) | 0.14562 (16) | 0.0290 (8) | |
H1 | 0.760 (4) | 0.974 (4) | 0.1038 (15) | 0.016 (10)* | |
H2 | 0.557 (5) | 0.687 (5) | 0.0293 (19) | 0.054 (15)* | |
H6 | 0.547 (4) | 0.855 (4) | 0.1835 (17) | 0.022 (11)* | |
H4 | 1.147 (5) | 1.005 (6) | 0.051 (2) | 0.063 (18)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.030 (2) | 0.028 (2) | 0.027 (2) | 0.0048 (19) | 0.0016 (18) | 0.002 (2) |
C2 | 0.033 (2) | 0.029 (2) | 0.027 (2) | 0.0069 (19) | −0.0019 (19) | 0.0031 (19) |
C3 | 0.025 (2) | 0.025 (2) | 0.029 (2) | −0.0021 (19) | −0.0019 (18) | −0.0036 (19) |
C4 | 0.023 (2) | 0.022 (2) | 0.028 (2) | 0.0034 (18) | 0.0008 (17) | −0.0017 (18) |
C5 | 0.022 (2) | 0.026 (2) | 0.024 (2) | 0.0038 (18) | 0.0012 (16) | −0.0031 (19) |
C6 | 0.024 (2) | 0.024 (2) | 0.030 (2) | −0.0012 (19) | −0.0008 (17) | 0.0043 (19) |
C7 | 0.016 (2) | 0.033 (2) | 0.028 (2) | −0.0005 (19) | −0.0013 (16) | −0.005 (2) |
C8 | 0.023 (2) | 0.032 (2) | 0.020 (2) | −0.0024 (19) | −0.0045 (16) | −0.0044 (19) |
C9 | 0.029 (2) | 0.030 (2) | 0.028 (2) | −0.003 (2) | −0.0027 (18) | 0.001 (2) |
C10 | 0.029 (2) | 0.042 (3) | 0.026 (2) | −0.004 (2) | −0.0007 (18) | 0.004 (2) |
C11 | 0.036 (3) | 0.035 (3) | 0.038 (3) | −0.008 (2) | −0.013 (2) | 0.012 (2) |
C12 | 0.031 (3) | 0.035 (3) | 0.033 (3) | 0.005 (2) | −0.0113 (19) | 0.004 (2) |
C13 | 0.024 (2) | 0.033 (2) | 0.022 (2) | −0.003 (2) | 0.0010 (17) | 0.0024 (19) |
C14 | 0.025 (2) | 0.0135 (19) | 0.032 (2) | −0.0007 (18) | 0.0037 (18) | 0.0023 (18) |
C15 | 0.020 (2) | 0.020 (2) | 0.024 (2) | −0.0018 (17) | 0.0019 (16) | 0.0034 (17) |
C16 | 0.028 (2) | 0.026 (2) | 0.035 (3) | 0.0001 (19) | 0.0041 (18) | 0.002 (2) |
C17 | 0.027 (2) | 0.030 (2) | 0.037 (3) | 0.001 (2) | −0.0058 (19) | 0.006 (2) |
C18 | 0.030 (2) | 0.042 (3) | 0.027 (2) | −0.003 (2) | −0.0059 (19) | 0.001 (2) |
C19 | 0.030 (3) | 0.052 (3) | 0.035 (3) | 0.007 (2) | 0.001 (2) | −0.011 (2) |
C20 | 0.021 (2) | 0.040 (3) | 0.036 (3) | 0.007 (2) | −0.0061 (18) | −0.005 (2) |
N1 | 0.024 (2) | 0.028 (2) | 0.024 (2) | −0.0014 (16) | 0.0035 (15) | −0.0011 (18) |
N2 | 0.027 (2) | 0.0244 (19) | 0.025 (2) | 0.0003 (16) | −0.0005 (14) | −0.0031 (16) |
N3 | 0.024 (2) | 0.0277 (19) | 0.030 (2) | −0.0027 (17) | 0.0007 (15) | −0.0037 (17) |
N4 | 0.029 (2) | 0.035 (2) | 0.023 (2) | −0.0048 (17) | 0.0045 (16) | −0.0022 (18) |
C1—C2 | 1.515 (5) | C10—C11 | 1.382 (6) |
C1—C6 | 1.516 (5) | C10—H10A | 0.930 |
C1—H1A | 0.970 | C11—C12 | 1.390 (6) |
C1—H1B | 0.970 | C11—H11A | 0.930 |
C2—C3 | 1.527 (5) | C12—C13 | 1.381 (5) |
C2—H2A | 0.970 | C12—H12A | 0.930 |
C2—H2B | 0.970 | C13—H13A | 0.930 |
C3—C4 | 1.530 (5) | C14—N3 | 1.301 (5) |
C3—H3A | 0.970 | C14—N1 | 1.352 (5) |
C3—H3B | 0.970 | C14—C15 | 1.501 (5) |
C4—N2 | 1.476 (5) | C15—C16 | 1.386 (5) |
C4—C5 | 1.537 (5) | C15—C20 | 1.394 (5) |
C4—H4A | 0.980 | C16—C17 | 1.399 (5) |
C5—N1 | 1.467 (5) | C16—H16A | 0.930 |
C5—C6 | 1.536 (5) | C17—C18 | 1.367 (6) |
C5—H5A | 0.980 | C17—H17A | 0.930 |
C6—H6A | 0.970 | C18—C19 | 1.383 (6) |
C6—H6B | 0.970 | C18—H18A | 0.930 |
C7—N4 | 1.293 (5) | C19—C20 | 1.387 (6) |
C7—N2 | 1.352 (5) | C19—H19A | 0.930 |
C7—C8 | 1.503 (6) | C20—H20A | 0.930 |
C8—C13 | 1.389 (5) | N1—H1 | 0.83 (4) |
C8—C9 | 1.397 (5) | N2—H2 | 0.91 (4) |
C9—C10 | 1.383 (5) | N3—H4 | 0.85 (4) |
C9—H9A | 0.930 | N4—H6 | 0.90 (4) |
C2—C1—C6 | 110.7 (3) | C10—C9—H9A | 119.7 |
C2—C1—H1A | 109.5 | C8—C9—H9A | 119.7 |
C6—C1—H1A | 109.5 | C11—C10—C9 | 120.0 (4) |
C2—C1—H1B | 109.5 | C11—C10—H10A | 120.0 |
C6—C1—H1B | 109.5 | C9—C10—H10A | 120.0 |
H1A—C1—H1B | 108.1 | C10—C11—C12 | 119.9 (4) |
C1—C2—C3 | 110.9 (3) | C10—C11—H11A | 120.0 |
C1—C2—H2A | 109.5 | C12—C11—H11A | 120.0 |
C3—C2—H2A | 109.5 | C13—C12—C11 | 120.1 (4) |
C1—C2—H2B | 109.5 | C13—C12—H12A | 120.0 |
C3—C2—H2B | 109.5 | C11—C12—H12A | 120.0 |
H2A—C2—H2B | 108.1 | C12—C13—C8 | 120.6 (4) |
C2—C3—C4 | 112.0 (3) | C12—C13—H13A | 119.7 |
C2—C3—H3A | 109.2 | C8—C13—H13A | 119.7 |
C4—C3—H3A | 109.2 | N3—C14—N1 | 120.4 (4) |
C2—C3—H3B | 109.2 | N3—C14—C15 | 124.3 (4) |
C4—C3—H3B | 109.2 | N1—C14—C15 | 115.2 (3) |
H3A—C3—H3B | 107.9 | C16—C15—C20 | 118.1 (4) |
N2—C4—C3 | 109.8 (3) | C16—C15—C14 | 120.1 (3) |
N2—C4—C5 | 111.9 (3) | C20—C15—C14 | 121.8 (3) |
C3—C4—C5 | 110.7 (3) | C15—C16—C17 | 120.5 (4) |
N2—C4—H4A | 108.1 | C15—C16—H16A | 119.7 |
C3—C4—H4A | 108.1 | C17—C16—H16A | 119.7 |
C5—C4—H4A | 108.1 | C18—C17—C16 | 120.5 (4) |
N1—C5—C6 | 111.3 (3) | C18—C17—H17A | 119.7 |
N1—C5—C4 | 109.8 (3) | C16—C17—H17A | 119.7 |
C6—C5—C4 | 109.5 (3) | C17—C18—C19 | 119.9 (4) |
N1—C5—H5A | 108.7 | C17—C18—H18A | 120.1 |
C6—C5—H5A | 108.7 | C19—C18—H18A | 120.1 |
C4—C5—H5A | 108.7 | C18—C19—C20 | 119.8 (4) |
C1—C6—C5 | 111.5 (3) | C18—C19—H19A | 120.1 |
C1—C6—H6A | 109.3 | C20—C19—H19A | 120.1 |
C5—C6—H6A | 109.3 | C19—C20—C15 | 121.3 (4) |
C1—C6—H6B | 109.3 | C19—C20—H20A | 119.4 |
C5—C6—H6B | 109.3 | C15—C20—H20A | 119.4 |
H6A—C6—H6B | 108.0 | C14—N1—C5 | 123.3 (3) |
N4—C7—N2 | 120.5 (4) | C14—N1—H1 | 118 (3) |
N4—C7—C8 | 124.2 (4) | C5—N1—H1 | 118 (3) |
N2—C7—C8 | 115.4 (3) | C7—N2—C4 | 121.9 (3) |
C13—C8—C9 | 118.9 (4) | C7—N2—H2 | 124 (3) |
C13—C8—C7 | 121.9 (3) | C4—N2—H2 | 114 (3) |
C9—C8—C7 | 119.3 (3) | C14—N3—H4 | 103 (3) |
C10—C9—C8 | 120.5 (4) | C7—N4—H6 | 111 (2) |
C6—C1—C2—C3 | −56.1 (4) | C7—C8—C13—C12 | 179.1 (3) |
C1—C2—C3—C4 | 55.4 (4) | N3—C14—C15—C16 | −32.1 (5) |
C2—C3—C4—N2 | −179.6 (3) | N1—C14—C15—C16 | 149.3 (3) |
C2—C3—C4—C5 | −55.5 (4) | N3—C14—C15—C20 | 145.9 (4) |
N2—C4—C5—N1 | −58.8 (4) | N1—C14—C15—C20 | −32.8 (5) |
C3—C4—C5—N1 | 178.4 (3) | C20—C15—C16—C17 | −0.4 (5) |
N2—C4—C5—C6 | 178.6 (3) | C14—C15—C16—C17 | 177.6 (3) |
C3—C4—C5—C6 | 55.8 (4) | C15—C16—C17—C18 | −0.1 (5) |
C2—C1—C6—C5 | 58.1 (4) | C16—C17—C18—C19 | 0.6 (6) |
N1—C5—C6—C1 | −179.4 (3) | C17—C18—C19—C20 | −0.6 (6) |
C4—C5—C6—C1 | −57.7 (4) | C18—C19—C20—C15 | 0.1 (6) |
N4—C7—C8—C13 | −142.5 (4) | C16—C15—C20—C19 | 0.4 (5) |
N2—C7—C8—C13 | 37.2 (5) | C14—C15—C20—C19 | −177.6 (3) |
N4—C7—C8—C9 | 36.5 (5) | N3—C14—N1—C5 | −3.0 (5) |
N2—C7—C8—C9 | −143.8 (3) | C15—C14—N1—C5 | 175.8 (3) |
C13—C8—C9—C10 | −2.0 (5) | C4—C5—N1—C14 | 162.9 (3) |
C7—C8—C9—C10 | 178.9 (3) | C6—C5—N1—C14 | −75.5 (4) |
C8—C9—C10—C11 | 2.5 (5) | N4—C7—N2—C4 | −9.2 (5) |
C9—C10—C11—C12 | −1.0 (6) | C8—C7—N2—C4 | 171.1 (3) |
C10—C11—C12—C13 | −1.0 (6) | C3—C4—N2—C7 | −144.8 (3) |
C11—C12—C13—C8 | 1.5 (5) | C5—C4—N2—C7 | 92.1 (4) |
C9—C8—C13—C12 | 0.0 (5) |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2···N3i | 0.91 (4) | 2.12 (5) | 3.024 (5) | 172 (4) |
N1—H1···N4 | 0.83 (4) | 2.14 (4) | 2.898 (5) | 151 (3) |
Symmetry code: (i) x−1/2, −y+3/2, −z. |
Experimental details
Crystal data | |
Chemical formula | C20H24N4 |
Mr | 320.43 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 173 |
a, b, c (Å) | 8.696 (5), 8.698 (5), 22.806 (13) |
V (Å3) | 1725.1 (17) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.20 × 0.10 × 0.10 |
Data collection | |
Diffractometer | Siemens SMART CCD diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.985, 0.993 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 7152, 1773, 1505 |
Rint | 0.098 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.059, 0.119, 1.06 |
No. of reflections | 1773 |
No. of parameters | 233 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.19, −0.21 |
Computer programs: SMART (Siemens, 1996), SAINT (Siemens, 1996), SAINT, SHELXS97 (Sheldrick, 1990), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997), SHELXL97.
C4—N2 | 1.476 (5) | C7—C8 | 1.503 (6) |
C4—C5 | 1.537 (5) | C14—N3 | 1.301 (5) |
C5—N1 | 1.467 (5) | C14—N1 | 1.352 (5) |
C7—N4 | 1.293 (5) | C14—C15 | 1.501 (5) |
C7—N2 | 1.352 (5) | ||
N2—C4—C5 | 111.9 (3) | N3—C14—N1 | 120.4 (4) |
N1—C5—C4 | 109.8 (3) | N3—C14—C15 | 124.3 (4) |
N4—C7—N2 | 120.5 (4) | N1—C14—C15 | 115.2 (3) |
N4—C7—C8 | 124.2 (4) | C14—N1—C5 | 123.3 (3) |
N2—C7—C8 | 115.4 (3) | C7—N2—C4 | 121.9 (3) |
N2—C4—C5—N1 | −58.8 (4) | N4—C7—N2—C4 | −9.2 (5) |
N3—C14—N1—C5 | −3.0 (5) | C8—C7—N2—C4 | 171.1 (3) |
C15—C14—N1—C5 | 175.8 (3) | C5—C4—N2—C7 | 92.1 (4) |
C4—C5—N1—C14 | 162.9 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2···N3i | 0.91 (4) | 2.12 (5) | 3.024 (5) | 172 (4) |
N1—H1···N4 | 0.83 (4) | 2.14 (4) | 2.898 (5) | 151 (3) |
Symmetry code: (i) x−1/2, −y+3/2, −z. |
Bis(amidinate) compounds, {[RC(NR')2]2}2−, are extensively used as ligands for transition metals, lanthanides and main group elements, towards which they act most frequently as tetradentate 8-electron donors (Barker & Kilner, 1994; Edelmann, 1994). Recently, linked bis(amidinate) compounds, in which the two anionic moieties are linked by a covalent bridge, have received increasing attention, because of their unusual ligand geometry and different coordination behavior (Whitener et al., 1999). This kind of dianion also exhibits versatility in its binding modes and, through varying the substituents, presents a flexible system in steric bulk and electronic properties of the ligands and their complexes. In addition to the two previously reported examples (Hagadorn & Arnold, 1998; Bambirra et al., 2001), we also developed a method to prepare a new kind of linked bis(amidinate) ligand and investigated its chemistry (Li, Weng, Wei & Liu, 2002). Neutral multidentate ligands bearing nitrogen donor atoms, including porphyrins, metalloporphyrins (Ellis et al., 1990), and 1,1-dimethylbiguanide (Lemoine et al., 1996), are promising systems for applications in catalysis. We describe here the synthesis of a new neutral chiral linked bis(benzamidinate) ligand derived from a lithium complex. The title compound, (I), has four nitrogen donor atoms and its crystal structure is presented here.
Selected geometric parameters of (I) are listed in Table 1. The molecular structure is illustrated in Fig. 1. The cyclohexane ring adopts a chair conformation. The two N—C—N fragments are nearly coplanar with the ring atoms to which they are attached, with torsion angles −3.0 (5) and −9.2 (5)°. The dihedral angles between the N—C—N fragments and the phenyl rings are 35.9 (3) and 32.5 (4)°.
The two nitrogen atoms linked to the cyclohexane ring are both sp2-hybridized (sum of angles around N1 and N2 are 358.9 and 359.6°, respectively). The other two nitrogen atoms, N3 and N4, are attached to the amidinate carbon atoms with double bonds. These double bonds, N4—C7 [1.293 (5) Å] and N3—C14 [1.301 (5) Å], are considerably shorter than the single bonds, N2—C4 [1.476 (5) Å] and N1—C5 [1.476 (5) Å]. By contrast, in the analogous Li[(1R,2R)-(-)-1-{NC(Ph)N(SiMe3)}-2-(NHSiMe3)-C6H10] (II) (Li, Weng, Wei & Liu, 2002), the anionic N—C—N fragment has some degree of π-electron delocalization and the bond distances between nitrogen and carbon are similar [1.337 (2) and 1.325 (12) Å]. These values are intermediate between the C—N bond lengths in (I). In addition, the bonds C7—C8 [1.503 (6) Å] and C14—C15 [1.501 (5) Å] are a little shorter than the corresponding bonds in (II) [1.513 (16) Å], in accordance with conjugation between the C═N double bonds and the phenyl groups.