Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S0108270106014934/gg3015sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S0108270106014934/gg3015Isup2.hkl |
CCDC reference: 612438
An NMR tube was charged with U(BH4)4 (9.0 mg, 30 µmol), 18-crown-6 (7.9 mg, 30 µmol) and THF-d8 (0.4 ml) under argon gas. After dissolution of the products, pentane was added and green crystals of (I) were formed after 4 d (4.5 mg, 35% yield).
The H atoms bound to B atoms were found in difference Fourier maps and treated as riding atoms, with Uiso(H) = 1.2Ueq(B). All other H atoms were introduced in calculated positions as riding atoms, with C—H = 0.97 Å and with Uiso(H) = 1.2Ueq(C).
Data collection: COLLECT (Nonius, 1998); cell refinement: HKL-2000 (Otwinowski & Minor, 1997); data reduction: HKL-2000; program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1999); software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003).
Fig. 1. A view of compound (I), with the atom-numbering scheme. The H atoms of the crown ether have been omitted for clarity. Displacement ellipsoids are drawn at the 30% probability level. |
[U2(BH4)6O(C12H24O6)] | F(000) = 1560 |
Mr = 845.42 | Dx = 2.036 Mg m−3 |
Orthorhombic, Pca21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2c -2ac | Cell parameters from 17685 reflections |
a = 16.4251 (7) Å | θ = 3.2–25.7° |
b = 10.2676 (5) Å | µ = 11.75 mm−1 |
c = 16.3550 (7) Å | T = 100 K |
V = 2758.2 (2) Å3 | Irregular, translucent light green |
Z = 4 | 0.15 × 0.12 × 0.10 mm |
Nonius KappaCCD area-detector diffractometer | 5193 independent reflections |
Radiation source: fine-focus sealed tube | 4656 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.062 |
Detector resolution: 18 pixels mm-1 | θmax = 25.7°, θmin = 3.2° |
ϕ scans | h = −20→20 |
Absorption correction: part of the refinement model (ΔF) (DELABS in PLATON; Spek, 2003) | k = −12→12 |
Tmin = 0.287, Tmax = 0.309 | l = −19→19 |
17685 measured reflections |
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)] = 0.029 | H-atom parameters constrained |
wR(F2) = 0.059 | w = 1/[σ2(Fo2) + (0.0073P)2 + 3.4303P] where P = (Fo2 + 2Fc2)/3 |
S = 1.03 | (Δ/σ)max = 0.002 |
5193 reflections | Δρmax = 0.74 e Å−3 |
245 parameters | Δρmin = −0.96 e Å−3 |
1 restraint | Absolute structure: Flack (1983), with how many Friedel pairs? |
Primary atom site location: structure-invariant direct methods | Absolute structure parameter: 0.006 (12) |
[U2(BH4)6O(C12H24O6)] | V = 2758.2 (2) Å3 |
Mr = 845.42 | Z = 4 |
Orthorhombic, Pca21 | Mo Kα radiation |
a = 16.4251 (7) Å | µ = 11.75 mm−1 |
b = 10.2676 (5) Å | T = 100 K |
c = 16.3550 (7) Å | 0.15 × 0.12 × 0.10 mm |
Nonius KappaCCD area-detector diffractometer | 5193 independent reflections |
Absorption correction: part of the refinement model (ΔF) (DELABS in PLATON; Spek, 2003) | 4656 reflections with I > 2σ(I) |
Tmin = 0.287, Tmax = 0.309 | Rint = 0.062 |
17685 measured reflections |
R[F2 > 2σ(F2)] = 0.029 | H-atom parameters constrained |
wR(F2) = 0.059 | Δρmax = 0.74 e Å−3 |
S = 1.03 | Δρmin = −0.96 e Å−3 |
5193 reflections | Absolute structure: Flack (1983), with how many Friedel pairs? |
245 parameters | Absolute structure parameter: 0.006 (12) |
1 restraint |
Experimental. crystal-to-detector distance 29 mm |
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. Structure solved by direct methods and subsequent Fourier-difference synthesis. All non-H atoms were refined with anisotropic displacement parameters. The H atoms bound to B atoms have been found on Fourier difference maps. All other H atoms were introduced at calculated positions. All H atoms were treated as riding atoms with an isotropic displacement parameter equal to 1.2 times that of the parent atom. 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 | ||
U1 | 1.126121 (16) | 0.12968 (3) | 0.69518 (2) | 0.02374 (7) | |
U2 | 0.955946 (16) | 0.28236 (3) | 0.533012 (17) | 0.02526 (7) | |
O1 | 1.1418 (3) | 0.3569 (6) | 0.7608 (4) | 0.0345 (14) | |
O2 | 1.2402 (4) | 0.2807 (6) | 0.6488 (3) | 0.0319 (13) | |
O3 | 1.2086 (4) | 0.0714 (6) | 0.5685 (3) | 0.0321 (13) | |
O4 | 1.1243 (4) | −0.1008 (6) | 0.6428 (3) | 0.0306 (13) | |
O5 | 1.0208 (3) | −0.0331 (6) | 0.7511 (3) | 0.0295 (12) | |
O6 | 1.0183 (3) | 0.2108 (6) | 0.7962 (3) | 0.0292 (13) | |
O7 | 1.0484 (4) | 0.1970 (5) | 0.6130 (3) | 0.0276 (12) | |
B1 | 1.2330 (6) | 0.0413 (12) | 0.8001 (6) | 0.035 (2) | |
H1 | 1.1684 | 0.0097 | 0.8102 | 0.042* | |
H2 | 1.2205 | 0.1479 | 0.8128 | 0.042* | |
H3 | 1.2473 | 0.0146 | 0.7296 | 0.042* | |
H4 | 1.2822 | −0.0130 | 0.8415 | 0.042* | |
B2 | 1.0672 (6) | 0.3426 (10) | 0.4217 (6) | 0.035 (2) | |
H5 | 1.0552 | 0.2223 | 0.4218 | 0.042* | |
H6 | 1.0873 | 0.3565 | 0.4944 | 0.042* | |
H7 | 1.0191 | 0.4148 | 0.4060 | 0.042* | |
H8 | 1.1271 | 0.4012 | 0.3807 | 0.042* | |
B3 | 0.8381 (7) | 0.2929 (11) | 0.4276 (6) | 0.033 (2) | |
H9 | 0.8646 | 0.4116 | 0.4450 | 0.040* | |
H10 | 0.8348 | 0.2228 | 0.4883 | 0.040* | |
H11 | 0.8835 | 0.2508 | 0.3891 | 0.040* | |
H12 | 0.7823 | 0.3109 | 0.4049 | 0.040* | |
B4 | 0.8582 (6) | 0.3096 (10) | 0.6596 (6) | 0.032 (2) | |
H13 | 0.8583 | 0.2170 | 0.6373 | 0.039* | |
H14 | 0.8323 | 0.3718 | 0.5887 | 0.039* | |
H15 | 0.9129 | 0.3462 | 0.6855 | 0.039* | |
H16 | 0.8040 | 0.3083 | 0.6924 | 0.039* | |
B5 | 0.9404 (6) | 0.0029 (10) | 0.5048 (6) | 0.034 (2) | |
H17 | 0.9772 | 0.0667 | 0.4636 | 0.041* | |
H18 | 0.9107 | 0.0656 | 0.5458 | 0.041* | |
H19 | 0.9021 | −0.0187 | 0.4641 | 0.041* | |
H20 | 0.9925 | −0.0844 | 0.5248 | 0.041* | |
B6 | 0.9902 (7) | 0.5522 (11) | 0.5780 (7) | 0.040 (2) | |
H21 | 0.9300 | 0.5166 | 0.5397 | 0.047* | |
H22 | 1.0268 | 0.4764 | 0.6191 | 0.047* | |
H23 | 0.9599 | 0.5987 | 0.6345 | 0.047* | |
H24 | 1.0231 | 0.6083 | 0.5364 | 0.047* | |
C1 | 1.2015 (6) | 0.4495 (9) | 0.7355 (6) | 0.045 (2) | |
H1A | 1.2170 | 0.5048 | 0.7810 | 0.054* | |
H1B | 1.1802 | 0.5041 | 0.6921 | 0.054* | |
C2 | 1.2736 (5) | 0.3724 (7) | 0.7056 (6) | 0.034 (2) | |
H2A | 1.3129 | 0.4287 | 0.6790 | 0.041* | |
H2B | 1.3002 | 0.3279 | 0.7507 | 0.041* | |
C3 | 1.2960 (6) | 0.2466 (10) | 0.5830 (5) | 0.041 (2) | |
H3A | 1.3399 | 0.1925 | 0.6035 | 0.050* | |
H3B | 1.3191 | 0.3244 | 0.5587 | 0.050* | |
C4 | 1.2467 (5) | 0.1741 (8) | 0.5219 (6) | 0.0339 (19) | |
H4A | 1.2061 | 0.2303 | 0.4972 | 0.041* | |
H4B | 1.2811 | 0.1385 | 0.4792 | 0.041* | |
C5 | 1.1802 (5) | −0.0346 (9) | 0.5190 (5) | 0.035 (2) | |
H5A | 1.2188 | −0.0538 | 0.4758 | 0.042* | |
H5B | 1.1281 | −0.0134 | 0.4943 | 0.042* | |
C6 | 1.1718 (6) | −0.1475 (9) | 0.5748 (5) | 0.036 (2) | |
H6A | 1.1443 | −0.2190 | 0.5477 | 0.043* | |
H6B | 1.2248 | −0.1772 | 0.5931 | 0.043* | |
C7 | 1.0990 (5) | −0.2043 (7) | 0.6967 (6) | 0.0322 (17) | |
H7A | 1.1354 | −0.2114 | 0.7433 | 0.039* | |
H7B | 1.0978 | −0.2871 | 0.6682 | 0.039* | |
C8 | 1.0152 (6) | −0.1651 (8) | 0.7234 (5) | 0.0301 (19) | |
H8A | 0.9773 | −0.1715 | 0.6781 | 0.036* | |
H8B | 0.9964 | −0.2211 | 0.7672 | 0.036* | |
C9 | 0.9415 (6) | 0.0185 (10) | 0.7716 (6) | 0.038 (2) | |
H9A | 0.9082 | −0.0485 | 0.7968 | 0.046* | |
H9B | 0.9140 | 0.0489 | 0.7227 | 0.046* | |
C10 | 0.9539 (5) | 0.1278 (9) | 0.8292 (5) | 0.034 (2) | |
H10A | 0.9040 | 0.1773 | 0.8352 | 0.040* | |
H10B | 0.9695 | 0.0949 | 0.8826 | 0.040* | |
C11 | 1.0280 (6) | 0.3248 (9) | 0.8467 (6) | 0.041 (2) | |
H11A | 1.0599 | 0.3042 | 0.8950 | 0.049* | |
H11B | 0.9754 | 0.3575 | 0.8639 | 0.049* | |
C12 | 1.0709 (6) | 0.4235 (9) | 0.7957 (6) | 0.036 (2) | |
H12A | 1.0354 | 0.4551 | 0.7526 | 0.043* | |
H12B | 1.0880 | 0.4968 | 0.8289 | 0.043* |
U11 | U22 | U33 | U12 | U13 | U23 | |
U1 | 0.02401 (12) | 0.02490 (13) | 0.02230 (12) | 0.00013 (12) | −0.00017 (15) | 0.00032 (14) |
U2 | 0.02642 (13) | 0.02488 (13) | 0.02448 (12) | 0.00198 (12) | −0.00072 (15) | 0.00197 (15) |
O1 | 0.031 (3) | 0.033 (3) | 0.039 (3) | −0.003 (3) | 0.006 (3) | −0.009 (3) |
O2 | 0.037 (3) | 0.031 (3) | 0.027 (3) | −0.006 (3) | 0.006 (3) | −0.001 (3) |
O3 | 0.032 (3) | 0.034 (3) | 0.030 (3) | 0.000 (3) | 0.004 (3) | −0.005 (2) |
O4 | 0.035 (3) | 0.030 (3) | 0.026 (3) | 0.000 (3) | 0.006 (3) | 0.000 (2) |
O5 | 0.027 (3) | 0.030 (3) | 0.032 (3) | 0.001 (3) | 0.005 (3) | 0.003 (3) |
O6 | 0.034 (3) | 0.027 (3) | 0.027 (3) | 0.002 (3) | 0.008 (2) | −0.001 (2) |
O7 | 0.031 (3) | 0.026 (3) | 0.027 (3) | 0.001 (2) | −0.008 (2) | −0.001 (2) |
B1 | 0.029 (6) | 0.045 (6) | 0.030 (6) | −0.001 (5) | −0.005 (4) | 0.008 (4) |
B2 | 0.038 (5) | 0.035 (6) | 0.031 (5) | 0.002 (5) | −0.006 (5) | 0.003 (4) |
B3 | 0.029 (5) | 0.035 (6) | 0.035 (6) | −0.003 (4) | −0.008 (5) | 0.008 (5) |
B4 | 0.030 (5) | 0.035 (5) | 0.033 (5) | 0.006 (4) | 0.000 (4) | 0.000 (4) |
B5 | 0.020 (5) | 0.042 (6) | 0.041 (6) | −0.009 (4) | −0.002 (4) | 0.003 (4) |
B6 | 0.044 (6) | 0.032 (6) | 0.043 (6) | 0.000 (5) | 0.004 (5) | −0.004 (5) |
C1 | 0.056 (6) | 0.031 (5) | 0.049 (5) | −0.012 (5) | 0.010 (5) | −0.012 (4) |
C2 | 0.044 (4) | 0.019 (4) | 0.039 (5) | −0.004 (3) | 0.008 (5) | −0.003 (4) |
C3 | 0.040 (5) | 0.050 (6) | 0.034 (5) | −0.015 (5) | 0.007 (5) | −0.001 (4) |
C4 | 0.040 (4) | 0.037 (5) | 0.024 (4) | −0.005 (4) | 0.018 (4) | 0.003 (4) |
C5 | 0.031 (4) | 0.042 (5) | 0.032 (5) | 0.003 (4) | 0.000 (4) | −0.014 (4) |
C6 | 0.039 (5) | 0.038 (5) | 0.031 (5) | 0.003 (4) | 0.002 (4) | −0.010 (4) |
C7 | 0.036 (4) | 0.024 (4) | 0.036 (4) | −0.002 (3) | −0.002 (5) | 0.012 (5) |
C8 | 0.039 (5) | 0.020 (4) | 0.032 (4) | −0.001 (3) | 0.000 (4) | 0.003 (3) |
C9 | 0.029 (5) | 0.044 (6) | 0.042 (5) | 0.002 (4) | −0.010 (4) | 0.001 (4) |
C10 | 0.025 (4) | 0.040 (5) | 0.036 (5) | −0.001 (4) | 0.011 (4) | 0.007 (4) |
C11 | 0.045 (5) | 0.035 (5) | 0.043 (5) | −0.010 (4) | 0.006 (5) | −0.011 (4) |
C12 | 0.037 (5) | 0.034 (5) | 0.037 (5) | 0.005 (4) | 0.010 (4) | −0.010 (4) |
U1—O1 | 2.581 (6) | B2—H7 | 1.1131 |
U1—O2 | 2.548 (6) | B2—H8 | 1.3337 |
U1—O3 | 2.548 (6) | B3—H9 | 1.3252 |
U1—O4 | 2.517 (6) | B3—H10 | 1.2273 |
U1—O5 | 2.574 (6) | B3—H11 | 1.0679 |
U1—O6 | 2.561 (6) | B3—H12 | 1.0062 |
U1—O7 | 1.979 (5) | B4—H13 | 1.0189 |
U1—H1 | 2.354 | B4—H14 | 1.3894 |
U1—H2 | 2.477 | B4—H15 | 1.0627 |
U1—H3 | 2.382 | B4—H16 | 1.0385 |
U2—O7 | 2.187 (5) | B5—H17 | 1.1177 |
U2—H5 | 2.519 | B5—H18 | 1.0502 |
U2—H6 | 2.373 | B5—H19 | 0.9417 |
U2—H7 | 2.690 | B5—H20 | 1.2822 |
U2—H9 | 2.466 | B6—H21 | 1.2264 |
U2—H10 | 2.207 | B6—H22 | 1.1916 |
U2—H11 | 2.657 | B6—H23 | 1.1533 |
U2—H13 | 2.435 | B6—H24 | 1.0418 |
U2—H14 | 2.408 | C1—C2 | 1.507 (13) |
U2—H15 | 2.674 | C1—H1A | 0.9700 |
U2—H17 | 2.513 | C1—H1B | 0.9700 |
U2—H18 | 2.355 | C2—H2A | 0.9700 |
U2—H21 | 2.445 | C2—H2B | 0.9700 |
U2—H22 | 2.703 | C3—C4 | 1.486 (13) |
U1—B1 | 2.617 (10) | C3—H3A | 0.9700 |
U2—B3 | 2.595 (10) | C3—H3B | 0.9700 |
U2—B4 | 2.635 (10) | C4—H4A | 0.9700 |
U2—B2 | 2.652 (11) | C4—H4B | 0.9700 |
U1—U2 | 4.1599 (4) | C5—C6 | 1.482 (13) |
U2—B5 | 2.918 (11) | C5—H5A | 0.9700 |
U2—B6 | 2.921 (11) | C5—H5B | 0.9700 |
O1—C1 | 1.427 (11) | C6—H6A | 0.9700 |
O1—C12 | 1.465 (10) | C6—H6B | 0.9700 |
O2—C2 | 1.432 (10) | C7—C8 | 1.499 (12) |
O2—C3 | 1.456 (11) | C7—H7A | 0.9700 |
O3—C5 | 1.435 (10) | C7—H7B | 0.9700 |
O3—C4 | 1.443 (10) | C8—H8A | 0.9700 |
O4—C6 | 1.441 (10) | C8—H8B | 0.9700 |
O4—C7 | 1.442 (9) | C9—C10 | 1.480 (13) |
O5—C8 | 1.431 (10) | C9—H9A | 0.9700 |
O5—C9 | 1.447 (11) | C9—H9B | 0.9700 |
O6—C11 | 1.442 (10) | C10—H10A | 0.9700 |
O6—C10 | 1.462 (10) | C10—H10B | 0.9700 |
B1—H1 | 1.1208 | C11—C12 | 1.490 (13) |
B1—H2 | 1.1327 | C11—H11A | 0.9700 |
B1—H3 | 1.2084 | C11—H11B | 0.9700 |
B1—H4 | 1.1935 | C12—H12A | 0.9700 |
B2—H5 | 1.2515 | C12—H12B | 0.9700 |
B2—H6 | 1.2426 | ||
O1—U1—O2 | 60.01 (18) | H22—B6—H24 | 117.9 |
O2—U1—O3 | 60.65 (19) | H23—B6—H24 | 121.2 |
O3—U1—O4 | 60.57 (18) | O1—C1—C2 | 106.5 (7) |
O4—U1—O5 | 60.15 (18) | O1—C1—H1A | 110.4 |
O5—U1—O6 | 61.13 (18) | C2—C1—H1A | 110.4 |
O6—U1—O1 | 60.45 (18) | O1—C1—H1B | 110.4 |
U1—O7—U2 | 173.8 (3) | C2—C1—H1B | 110.4 |
O7—U1—O4 | 95.1 (2) | H1A—C1—H1B | 108.6 |
O7—U1—O3 | 82.7 (2) | O2—C2—C1 | 104.7 (7) |
O7—U1—O2 | 93.4 (2) | O2—C2—H2A | 110.8 |
O4—U1—O2 | 118.68 (19) | C1—C2—H2A | 110.8 |
O7—U1—O6 | 83.0 (2) | O2—C2—H2B | 110.8 |
O4—U1—O6 | 121.13 (19) | C1—C2—H2B | 110.8 |
O3—U1—O6 | 165.71 (18) | H2A—C2—H2B | 108.9 |
O2—U1—O6 | 120.17 (19) | O2—C3—C4 | 106.0 (7) |
O7—U1—O5 | 92.0 (2) | O2—C3—H3A | 110.5 |
O3—U1—O5 | 119.61 (19) | C4—C3—H3A | 110.5 |
O2—U1—O5 | 174.54 (19) | O2—C3—H3B | 110.5 |
O7—U1—O1 | 91.8 (2) | C4—C3—H3B | 110.5 |
O4—U1—O1 | 173.04 (19) | H3A—C3—H3B | 108.7 |
O3—U1—O1 | 119.85 (19) | O3—C4—C3 | 104.3 (7) |
O5—U1—O1 | 120.42 (18) | O3—C4—H4A | 110.9 |
C1—O1—C12 | 110.4 (7) | C3—C4—H4A | 110.9 |
C1—O1—U1 | 123.4 (5) | O3—C4—H4B | 110.9 |
C12—O1—U1 | 120.3 (5) | C3—C4—H4B | 110.9 |
C2—O2—C3 | 113.4 (6) | H4A—C4—H4B | 108.9 |
C2—O2—U1 | 119.3 (5) | O3—C5—C6 | 106.0 (7) |
C3—O2—U1 | 122.4 (5) | O3—C5—H5A | 110.5 |
C5—O3—C4 | 113.5 (6) | C6—C5—H5A | 110.5 |
C5—O3—U1 | 117.6 (5) | O3—C5—H5B | 110.5 |
C4—O3—U1 | 119.2 (5) | C6—C5—H5B | 110.5 |
C6—O4—C7 | 112.5 (7) | H5A—C5—H5B | 108.7 |
C6—O4—U1 | 124.7 (5) | O4—C6—C5 | 105.4 (7) |
C7—O4—U1 | 119.2 (5) | O4—C6—H6A | 110.7 |
C8—O5—C9 | 111.2 (7) | C5—C6—H6A | 110.7 |
C8—O5—U1 | 123.0 (5) | O4—C6—H6B | 110.7 |
C9—O5—U1 | 116.7 (5) | C5—C6—H6B | 110.7 |
C11—O6—C10 | 109.9 (6) | H6A—C6—H6B | 108.8 |
C11—O6—U1 | 123.9 (5) | O4—C7—C8 | 104.1 (6) |
C10—O6—U1 | 123.4 (5) | O4—C7—H7A | 110.9 |
H1—B1—H2 | 94.7 | C8—C7—H7A | 110.9 |
H1—B1—H3 | 105.1 | O4—C7—H7B | 110.9 |
H2—B1—H3 | 115.5 | C8—C7—H7B | 110.9 |
H1—B1—H4 | 115.0 | H7A—C7—H7B | 108.9 |
H2—B1—H4 | 118.1 | O5—C8—C7 | 106.7 (7) |
H3—B1—H4 | 107.6 | O5—C8—H8A | 110.4 |
H5—B2—H6 | 98.8 | C7—C8—H8A | 110.4 |
H5—B2—H7 | 123.0 | O5—C8—H8B | 110.4 |
H6—B2—H7 | 109.4 | C7—C8—H8B | 110.4 |
H5—B2—H8 | 124.2 | H8A—C8—H8B | 108.6 |
H6—B2—H8 | 103.5 | O5—C9—C10 | 107.5 (7) |
H7—B2—H8 | 96.2 | O5—C9—H9A | 110.2 |
H9—B3—H10 | 112.3 | C10—C9—H9A | 110.2 |
H9—B3—H11 | 105.6 | O5—C9—H9B | 110.2 |
H10—B3—H11 | 105.7 | C10—C9—H9B | 110.2 |
H9—B3—H12 | 102.1 | H9A—C9—H9B | 108.5 |
H10—B3—H12 | 111.5 | O6—C10—C9 | 107.8 (7) |
H11—B3—H12 | 119.5 | O6—C10—H10A | 110.1 |
H13—B4—H14 | 97.5 | C9—C10—H10A | 110.1 |
H13—B4—H15 | 118.0 | O6—C10—H10B | 110.1 |
H14—B4—H15 | 115.5 | C9—C10—H10B | 110.1 |
H13—B4—H16 | 100.1 | H10A—C10—H10B | 108.5 |
H14—B4—H16 | 100.0 | O6—C11—C12 | 106.5 (7) |
H15—B4—H16 | 121.5 | O6—C11—H11A | 110.4 |
H17—B5—H18 | 106.0 | C12—C11—H11A | 110.4 |
H17—B5—H19 | 94.2 | O6—C11—H11B | 110.4 |
H18—B5—H19 | 106.7 | C12—C11—H11B | 110.4 |
H17—B5—H20 | 101.7 | H11A—C11—H11B | 108.6 |
H18—B5—H20 | 125.1 | O1—C12—C11 | 106.1 (7) |
H19—B5—H20 | 117.5 | O1—C12—H12A | 110.5 |
H21—B6—H22 | 120.0 | C11—C12—H12A | 110.5 |
H21—B6—H23 | 100.6 | O1—C12—H12B | 110.5 |
H22—B6—H23 | 92.1 | C11—C12—H12B | 110.5 |
H21—B6—H24 | 104.5 | H12A—C12—H12B | 108.7 |
C12—O1—C1—C2 | 176.5 (7) | C6—O4—C7—C8 | −143.3 (7) |
C3—O2—C2—C1 | 148.9 (8) | C9—O5—C8—C7 | 174.9 (7) |
O1—C1—C2—O2 | 50.8 (10) | O4—C7—C8—O5 | −50.3 (8) |
C2—O2—C3—C4 | −168.7 (7) | C8—O5—C9—C10 | 157.2 (7) |
C5—O3—C4—C3 | −160.6 (7) | C11—O6—C10—C9 | 175.2 (7) |
O2—C3—C4—O3 | −53.5 (9) | O5—C9—C10—O6 | 47.2 (9) |
C4—O3—C5—C6 | 159.7 (7) | C10—O6—C11—C12 | −160.3 (7) |
C7—O4—C6—C5 | 170.4 (7) | C1—O1—C12—C11 | −159.5 (8) |
O3—C5—C6—O4 | 50.9 (8) | O6—C11—C12—O1 | −50.0 (9) |
Experimental details
Crystal data | |
Chemical formula | [U2(BH4)6O(C12H24O6)] |
Mr | 845.42 |
Crystal system, space group | Orthorhombic, Pca21 |
Temperature (K) | 100 |
a, b, c (Å) | 16.4251 (7), 10.2676 (5), 16.3550 (7) |
V (Å3) | 2758.2 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 11.75 |
Crystal size (mm) | 0.15 × 0.12 × 0.10 |
Data collection | |
Diffractometer | Nonius KappaCCD area-detector diffractometer |
Absorption correction | Part of the refinement model (ΔF) (DELABS in PLATON; Spek, 2003) |
Tmin, Tmax | 0.287, 0.309 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 17685, 5193, 4656 |
Rint | 0.062 |
(sin θ/λ)max (Å−1) | 0.610 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.059, 1.03 |
No. of reflections | 5193 |
No. of parameters | 245 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.74, −0.96 |
Absolute structure | Flack (1983), with how many Friedel pairs? |
Absolute structure parameter | 0.006 (12) |
Computer programs: COLLECT (Nonius, 1998), HKL-2000 (Otwinowski & Minor, 1997), HKL-2000, SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 1999), SHELXTL and PLATON (Spek, 2003).
Examples of hexa-coordinated uranium(18-crown-6) complexes are uncommon. The first to be reported were uranium(IV) complexes, in which the coordination sphere was completed by three chloride groups (de Villardi et al., 1978; Bombieri et al., 1978). A bis(tetrahydroborate) uranium(III) complex with dicyclohexyl(18-crown-6) has also been described (Dejean et al., 1987), as well as several uranyl complexes (Thuéry et al.,1995, and references therein). In the course of our studies of the reactions of tetramethylethylene with U(BH4)4 (Villiers & Ephritikhine, 1995), we obtained the title compound, (I), which appeared to be a dinuclear molecular complex of unprecedented geometry.
The asymmetric unit of (I) comprises one complex molecule (Fig. 1). The two U centres are bridged by the µ2-oxo atom O7 in an asymmetric fashion, this atom being closer to U1 than to U2 by ca 0.21 Å, the ensemble being close to linearity [U1—O7—U2 = 173.8 (3)°]. A search of the Cambridge Structural Database (CSD; Version 5.27; Allen, 2002) shows that quasi-linear (µ2-oxo)U2 systems are generally symmetrical, with U—O bond lengths in the range 2.06–2.11 Å and the two U atoms in similar environments. Only one example of a system in which the bridge is nearly perfectly linear and the two bond lengths different (2.017 and 2.226 Å) has been described, but it is a mixed-valence UIII/UIV species (Korobkov et al., 2002). This asymmetry in the U—O bond lengths in (I) is probably indicative of an U1═ O7—U2 bonding scheme, associated with positive and negative partial charges on U1 and U2, respectively.
Atom U1 is located at the centre of the 18-crown-6 molecule, in which it is held by six bonds to the ether O atoms. The U—O(ether) bond lengths are in the range 2.517 (6)–2.581 (6) Å and their average value of 2.55 (2) Å is in good agreement with the values of 2.55 (9) Å (de Villardi et al., 1978) and 2.53 (5) Å (Bombieri et al., 1978) in similar systems. The six ether O atoms define a mean plane with an r.m.s. deviation of 0.22 Å, atom U1 being 0.014 (2) Å from this plane. The O—C—C—O torsion angles are all gauche [in the range 47.2 (9)–53.5 (9)°] and define a g+g−g+g−g+g− sequence (distorted D3d symmetry), commonly found in uncomplexed as well as complexed crown ethers (Fyles & Gandour, 1992). However, some C—O—C—C torsion angles deviate by as much as ca 37° from the ideal anti value [143.3 (7)–176.5 (7)°]. Oxo atom O7 and the tetrahydroborate group are located on either side of the crown ether mean plane and are axially bound to U1 [O7—U1···B1 178.0 (3)°]. The BH4 group is tridentate, with U1—H bond lengths in the range 2.35–2.48 Å [mean value 2.40 (5) Å] and B—H bond lengths in the range 1.12–1.21 Å [mean value 1.16 (4) Å]. It has been shown that the U···B distance in uranium tetrahydroborates is indicative of the nature (bi- or tridentate) of the bonding (Bernstein et al., 1972; Edelstein, 1981). The U1···B1 distance of 2.617 (10) Å in (I) agrees with the average distance for tridentate ligands from the CSD, 2.58 (6) Å [For how many hits?]. If the BH4 group is considered as a single donor atom, the uranium environment is a very distorted hexagonal bipyramid.
The second metal centre, U2, is bound to the bridging atom O7 and to five tetrahydroborate groups, among which three are tridentate (B2, B3, B4) and two bidentate (B5, B6). The tridentate ligands correspond to U2—H bond lengths in the range 2.21–2.69 Å [mean value 2.49 (15) Å], B—H bond lengths in the range 1.01–1.39 Å [mean value 1.17 (13) Å] and U2···B distances in the range 2.595 (10)–2.652 (11) Å [mean value 2.63 (2) Å]. These three groups are thus slightly farther from U2 than their counterpart is from U1, maybe as a result of the crowding around U2. For the two bidentate ligands, the U2—H bond lengths are in the range 2.36–2.70 Å [mean value 2.50 (13) Å], the B—H bond lengths are in the range 0.94–1.28 Å [mean value 1.13 (10) Å] and the U2···B distances are 2.918 (11) and 2.921 (11) Å, these last unambiguously evidencing the coordination mode. Indeed, there are only three well documented examples (i.e. with H atoms located, albeit with moderate reliability in certain cases) of bidentate tetrahydroborate complexes of UIV in the CSD (Bernstein et al., 1972; Rietz et al., 1978; Charpin et al., 1987), with an average U···B distance of 2.87 (3) Å [the mean U—H and B—H bond lengths are 2.38 (15) and 1.24 (8) Å, respectively]. In (I), the tetrahydroborate group in the trans position with respect to O7 is tridentate, the two bidentate ones being trans to each other. The four atoms B2, B4, B5 and B6 define a plane with an r.m.s. deviation of 0.079 Å, which is nearly parallel to the mean plane defined by the six O atoms of the crown ether, with a dihedral angle of 8.7 (3)°. Atom U2 is only 0.133 (5) Å from this mean plane, with atoms O7 and B3 occupying the axial positions [O7—U2···B3 158.7 (3)°], the metal environment being thus distorted octahedral, if the tetrahydroborate groups are considered as single donor atoms. Surprisingly, one of the bidentate groups (B5) has the bite angle defined by the two coordinating H atoms roughly parallel to the mean B4 plane, whereas the other one (B6) is roughly perpendicular to it [dihedral angles between the BH2 and mean B4 planes 9.8 (3) and 89.34 (12)°, respectively]. As a consequence, the B···U2···B angles involving successive B atoms in the B4 plane are much larger around B5 [B2···U2···B5 100.4 (3)° and B4···U2···B5 100.1 (3)°] than around B6 [B2···U2···B6 and B4···U2···B6 79.6 (3)°]. This may also be the reason why the O7—U2···B3 angle deviates from linearity, the B3···U2···B5 angle [82.5 (3)°] being smaller than B3···U2···B6 [105.8 (3)°], due to steric hindrance with the out-of-plane H atom in the latter case.
Complex (I) thus comprises two U atoms in completely different environments bridged by an asymmetric oxo group. The environment around U1 is comparable with that of the UIII ion in the bis(tetrahydroborate) dicyclohexyl(18-crown-6) complex (Dejean et al., 1987), one of the BH4 groups being replaced by O7. The coordination of metal atom U2 is reminiscent of that observed in [U(BH4)4OR2] (R = methyl or ethyl) (Rietz et al., 1978). In these latter compounds, which are linear polymers, the three terminal BH4 groups are tridentate, one of them being trans with respect to the ether O atom, while the two bridging BH4 groups, trans with respect to one another, are bidentate. The first coordination sphere of the U atom is thus close to that of U2 in (I), with the same total coordination number of 14, but the ether is replaced by an oxo group in (I), which is further a molecular discrete species. No significant hydrogen-bonding interaction is present in the packing of (I), which is rather loose (66.3% filled space).