(Borohydrido)(18-crown-6)potassium and (borohydrido)(dibenzo-18-crown-6)(tetra­hydro­furan)potassium

In the two compounds (borohydrido)(1,4,7,10,13,16-hexa­oxacyclo­octa­decane-κ⁶O)potassium, [K(BH₄)(C₁₂H₂₄O₆)], (I), and (borohydrido)(1,4,7,10,13,16-hexa­oxa-2,3:11,12-di­benzo­cyclo­octa­deca-2,11-diene-κ⁶O)(tetra­hydro­furan)­potassium, [K(BH₄)(C₄H₈O)(C₂₀H₂₄O₆)], (II), the K atom is bound to the six O atoms of the crown ether and to a tridentate borohydride group, with further coordination to a tetra­hydro­furan mol­ecule in (II). The alkali metal ion environment is thus distorted hexa­gonal–pyramidal in (I) and bipyramidal in (II).

S1. Comment

Alkali metal borohydrides are very versatile reagents in organic and coordination chemistry, and the synthesis of their molecular complexes with donor ligands is of major interest for the determination of their structures and the control of their properties. While the crystal structures of some ether and amine adducts of LiBH₄ and NaBH₄ have been reported (Reger et al., 1997; Giese et al., 1999), no such compound of KBH₄ has been structurally characterized to date. Here, we report the structures of two adducts of KBH₄ with the crown ethers 18-crown-6 [compound (I)] and dibenzo-18-crown-6 [compound (II)].

Complex (I) presents the characteristic features of compounds containing the [K(18-crown-6)] moiety (Fig. 1). The K⁺ ion is located at the centre of the 18-crown-6 ligand and it is coordinated by the six O atoms. The K1—O bond lengths are in the range 2.7532 (17)–2.9135 (16) Å [mean value 2.85 (6) Å] (Table 1). The metal centre is located 0.6416 (8) Å from the O₆ mean plane (r.m.s. deviation 0.19 Å). The borohydride anion is tridentate, with K1—H bond lengths in the range 2.71–2.84 Å, whereas the K1···B1—H4 angle involving the terminal uncoordinated H atom is nearly linear, with a value of 176°. The K···B distance is significantly shorter in (I) than in KBH₄ (Luck & Schelter, 1999), with values of 2.947 (3) and 3.3640 (9) Å, respectively. The BH₄ moiety in (I) is slightly inclined with respect to the O₆ mean plane, with an angle between the K1···B1 line and the normal to the plane of 12.2°, and B1···K1—O angles of 90.12 (7), 95.44 (7), 95.30 (7)° for atoms O1, O2 and O3, and 112.47 (7), 112.54 (7) and 111.12 (7)° for atoms O4, O5 and O6, respectively. The crown ether moiety presents a usual conformation, with the gauche O—C—C—O torsion angles defining the sequence g⁺g⁻g⁺g⁻g⁺g⁻ and all the C—O—C—C torsion angles close to anti values (distorted D_3d symmetry), which is commonly found in uncomplexed as well as complexed crown ethers (Fyles & Gandour, 1992).

Complex (II) is different from (I) in two respects, namely the conformation of the more rigid dibenzo-18-crown-6 molecule and the presence of an additional tetrahydrofuran (THF) ligand (Fig. 2). The K⁺ cation is bound to the six O atoms of the crown ether, with K1—O bond lengths in the range 2.786 (2)–2.829 (2) Å [mean value 2.806 (17) Å], significantly shorter than in (I) (Table 2). This is probably a result of the different crown ether conformation, which in (II) adopts a curved shape with two orthogonal pseudo-symmetry planes perpendicular to the mean O₆ plane (r.m.s. deviation 0.11 Å), one containing atoms O3 and O6 and the other the centroids of the aromatic rings (approximate C_2v point group symmetry). The shortest K1—O bond lengths involve these atoms O3 and O6, indicating a pinching of the macrocycle along the O3—O6 line. The O—C—C—O torsion angles define the sequence cg⁺g⁻cg⁺g⁻, with all the C—O—C—C torsion angles close to 180°. This conformation is usual for potassium complexes of dibenzo-18-crown-6, as evidenced by the structures reported in the Cambridge Structural Database (CSD, Version 5.27; Allen, 2002). The K⁺ ion is located 0.6189 (11) Å from the O₆ mean plane, on the same side as the borohydride group. The latter is tridentate, with K1—H bond lengths in the range 2.75–2.93 Å, and the K1···B1—H4 angle is 175°. The K1···B1 distance of 2.993 (4) Å is slightly larger than in (I). The angle between the K1···B1 line and the normal to the O₆ mean plane is 0.8°, and the B1···K1—O angles are in the range 99.85 (10)–106.34 (10)°. The THF molecule is located on the concave side of the crown ether, with a K1—O7 bond length of 2.686 (3) Å, in good agreement with the mean value of 2.70 (15) Å for the K—O(THF) bonds in the CSD [How many hits?]. The O7—K1···B1 angle is 176.96 (11)° and the K⁺ cation is thus in a distorted hexagonal–bipyramidal environment, if the BH₄ group is considered as a single donor atom.

The 18-crown-6 and the dibenzo-18-crown-6 e thers thus form two stable 1:1 complexes with KBH₄ in refluxing THF, which makes these two ligands effective agents for the solubilization of KBH₄ in THF. Compounds (I) and (II) are new examples of crown ether complexes of alkali metal borohydrides, after [Li₂(18-crown-6)(BH₄)₂] (Antsyshkina et al., 1994) and [Na(15-crown-5)(BH₄)] (Gorbunov et al., 1985).

S2. Experimental

KBH₄, 18-crown-6 and dibenzo-18-crown-6 were purchased from Aldrich and used without further purification. The ¹H NMR spectrum was recorded with a Bruker DPX 200 instrument and referenced internally using the residual protonated solvent resonances relative to tetramethylsilane (δ = 0 p.p.m.). For compound (I), a 50 ml round-bottomed flask was charged with KBH₄ (13.7 mg, 0.25 mmol), 18-crown-6 (66 mg, 0.25 mmol) and tetrathydrofuran (THF) (2 ml). The mixture was refluxed gently for 48 h and then cooled to room temperature, giving crystals of (I) which were filtered off and dried under a vacuum (78.5 mg, 98% yield). Analysis, calculated for C₁₂H₂₈BKO₆ (318.25): C 45.29, H 8.87, B 3.40, K 12.29%; found: C 45.47, H 8.75, B 3.43, K 12.40%. ¹H NMR (THF-d₈, 200 MHz, 296 K, δ, p.p.m.): 3.53 (s, 24H, CH₂), −0.39 [quartet, 4H, BH₄, ¹J(¹¹B¹H = 81 Hz)]. For compound (II), an NMR tube was charged with KBH₄ (2.1 mg, 0.039 mmol), dibenzo-18-crown-6 (14 mg, 0.039 mmol) and THF (0.4 ml). The mixture was refluxed for 22 d, giving crystals of (II) in quantitative yield.

S3. Refinement

H atoms bound to B atoms were found in difference Fourier maps. The BH₄ group in both compounds was then constrained to an ideal tetrahedral geometry and the H atoms were treated as riding atoms, with B—H bond lengths of 1.15 Å and U_iso(H) = 1.2U_eq(B). All other H atoms were introduced in calculated positions as riding atoms, with C—H bond lengths of 0.93 (CH) or 0.97 Å (CH₂) and U_iso(H) = 1.2U_eq(C). Restraints on displacement parameters (ISOR) were applied for two C atoms of the coordinated THF molecule in (II).

Computing details

For both compounds, 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).

Figures

	Fig. 1. A view of compound (I), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii.
	Fig. 2. A view of compound (II), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level and H atoms are shown as small spheres of arbitrary radii.

(I) (borohydrido)(1,4,7,10,13,16-hexaoxacyclooctadecane-κ⁶O)potassium

Crystal data

[K(BH4)(C12H24O6)]	F(000) = 688
Mr = 318.25	Dx = 1.198 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 11824 reflections
a = 8.2049 (5) Å	θ = 2.8–25.7°
b = 11.9741 (8) Å	µ = 0.32 mm^−1
c = 17.9611 (12) Å	T = 100 K
V = 1764.6 (2) Å^3	Parallelepiped, colourless
Z = 4	0.30 × 0.30 × 0.25 mm

Data collection

Nonius KappaCCD area-detector diffractometer	2858 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.053
Graphite monochromator	θmax = 25.7°, θmin = 2.8°
ϕ scan with 2° steps	h = −10→10
11824 measured reflections	k = −14→14
3290 independent reflections	l = −21→21

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.035	H-atom parameters constrained
wR(F^2) = 0.083	w = 1/[σ^2(Fo^2) + (0.0331P)^2 + 0.2179P] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max = 0.001
3290 reflections	Δρmax = 0.15 e Å^−3
181 parameters	Δρmin = −0.14 e Å^−3
0 restraints	Absolute structure: Flack (1983), with how many Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.03 (4)

Special details

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-hydrogen atoms were refined with anisotropic displacement parameters. The H atoms bound to B have been found on the Fourier-difference map and introduced as riding atoms with an isotropic displacement parameter equal to 1.2 times that of the parent atom. All other hydrogen atoms were introduced at calculated positions 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
K1	0.62347 (6)	0.46724 (4)	0.93213 (3)	0.03555 (13)
B1	0.8097 (4)	0.6083 (2)	0.82802 (17)	0.0454 (7)
H1	0.8625	0.6082	0.8873	0.054*
H2	0.6793	0.6434	0.8292	0.054*
H3	0.8074	0.5185	0.8053	0.054*
H4	0.8896	0.6632	0.7902	0.054*
O1	0.8847 (2)	0.31688 (11)	0.93959 (8)	0.0361 (3)
O2	0.6374 (2)	0.26653 (13)	0.84067 (8)	0.0382 (4)
O3	0.3775 (2)	0.41827 (14)	0.83312 (9)	0.0445 (4)
O4	0.2973 (2)	0.55040 (14)	0.95743 (9)	0.0433 (4)
O5	0.5370 (2)	0.58289 (13)	1.06563 (10)	0.0447 (4)
O6	0.79900 (19)	0.43506 (12)	1.06931 (10)	0.0392 (4)
C1	0.8927 (3)	0.2187 (2)	0.89503 (13)	0.0406 (5)
H1A	0.8425	0.1565	0.9210	0.049*
H1B	1.0054	0.1998	0.8847	0.049*
C2	0.8036 (3)	0.2417 (2)	0.82377 (14)	0.0425 (6)
H2A	0.8533	0.3044	0.7982	0.051*
H2B	0.8094	0.1770	0.7914	0.051*
C3	0.5431 (3)	0.2816 (3)	0.77469 (14)	0.0511 (7)
H3A	0.5416	0.2129	0.7461	0.061*
H3B	0.5913	0.3396	0.7441	0.061*
C4	0.3720 (4)	0.3137 (2)	0.79575 (14)	0.0488 (6)
H4A	0.3048	0.3195	0.7515	0.059*
H4B	0.3251	0.2574	0.8281	0.059*
C5	0.2193 (3)	0.4653 (3)	0.84414 (15)	0.0503 (6)
H5A	0.1522	0.4144	0.8729	0.060*
H5B	0.1668	0.4777	0.7965	0.060*
C6	0.2372 (3)	0.5730 (2)	0.88456 (15)	0.0508 (7)
H6A	0.3124	0.6214	0.8582	0.061*
H6B	0.1326	0.6105	0.8876	0.061*
C7	0.3035 (4)	0.6485 (2)	1.00252 (16)	0.0526 (7)
H7A	0.1948	0.6789	1.0088	0.063*
H7B	0.3709	0.7047	0.9788	0.063*
C8	0.3735 (3)	0.6181 (2)	1.07661 (15)	0.0492 (6)
H8A	0.3705	0.6821	1.1097	0.059*
H8B	0.3103	0.5584	1.0990	0.059*
C9	0.6142 (4)	0.5552 (2)	1.13387 (13)	0.0483 (6)
H9A	0.5611	0.4910	1.1562	0.058*
H9B	0.6066	0.6174	1.1683	0.058*
C10	0.7891 (3)	0.5289 (2)	1.11829 (14)	0.0480 (6)
H10A	0.8415	0.5931	1.0956	0.058*
H10B	0.8451	0.5123	1.1645	0.058*
C11	0.9631 (3)	0.4123 (2)	1.04955 (14)	0.0425 (6)
H11A	1.0298	0.4078	1.0940	0.051*
H11B	1.0052	0.4720	1.0185	0.051*
C12	0.9697 (3)	0.3038 (2)	1.00811 (14)	0.0406 (6)
H12A	1.0822	0.2832	0.9986	0.049*
H12B	0.9196	0.2452	1.0375	0.049*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
K1	0.0340 (2)	0.0351 (2)	0.0376 (2)	−0.0005 (2)	−0.0027 (2)	0.0020 (2)
B1	0.0421 (15)	0.0411 (15)	0.0529 (18)	0.0003 (13)	0.0016 (14)	0.0111 (13)
O1	0.0388 (8)	0.0343 (7)	0.0353 (8)	0.0010 (8)	−0.0037 (8)	−0.0002 (6)
O2	0.0354 (8)	0.0486 (9)	0.0308 (8)	−0.0049 (8)	−0.0001 (7)	−0.0015 (7)
O3	0.0345 (8)	0.0552 (10)	0.0437 (9)	−0.0035 (9)	−0.0041 (8)	0.0002 (8)
O4	0.0406 (8)	0.0403 (9)	0.0490 (10)	0.0049 (8)	−0.0026 (7)	0.0034 (7)
O5	0.0459 (9)	0.0422 (9)	0.0459 (9)	0.0064 (8)	−0.0011 (8)	−0.0047 (9)
O6	0.0413 (8)	0.0362 (8)	0.0402 (9)	0.0011 (7)	−0.0046 (8)	−0.0054 (8)
C1	0.0380 (13)	0.0378 (12)	0.0462 (14)	0.0010 (12)	0.0055 (12)	−0.0029 (10)
C2	0.0429 (13)	0.0448 (14)	0.0396 (14)	−0.0020 (12)	0.0079 (11)	−0.0051 (11)
C3	0.0498 (15)	0.0696 (18)	0.0339 (14)	−0.0031 (14)	−0.0049 (11)	−0.0057 (12)
C4	0.0446 (13)	0.0624 (16)	0.0395 (13)	−0.0047 (15)	−0.0087 (13)	−0.0018 (12)
C5	0.0350 (12)	0.0644 (16)	0.0516 (15)	−0.0017 (14)	−0.0094 (11)	0.0116 (14)
C6	0.0401 (14)	0.0560 (16)	0.0562 (17)	0.0049 (13)	−0.0067 (12)	0.0142 (14)
C7	0.0478 (15)	0.0379 (14)	0.072 (2)	0.0085 (13)	0.0010 (14)	−0.0020 (13)
C8	0.0506 (14)	0.0422 (12)	0.0547 (16)	0.0066 (14)	0.0088 (15)	−0.0092 (12)
C9	0.0616 (16)	0.0422 (13)	0.0410 (13)	0.0014 (14)	−0.0050 (13)	−0.0091 (10)
C10	0.0556 (15)	0.0405 (13)	0.0479 (15)	0.0014 (13)	−0.0129 (12)	−0.0111 (12)
C11	0.0372 (13)	0.0415 (13)	0.0488 (16)	0.0021 (12)	−0.0112 (11)	0.0005 (11)
C12	0.0373 (13)	0.0410 (14)	0.0436 (14)	0.0056 (12)	−0.0061 (11)	0.0045 (11)

Geometric parameters (Å, º)

K1—O1	2.8023 (16)	C1—H1B	0.9700
K1—O2	2.9135 (16)	C2—H2A	0.9700
K1—O3	2.7532 (17)	C2—H2B	0.9700
K1—O4	2.8911 (17)	C3—C4	1.504 (4)
K1—O5	2.8584 (18)	C3—H3A	0.9700
K1—O6	2.8797 (17)	C3—H3B	0.9700
K1—H1	2.7097	C4—H4A	0.9700
K1—H3	2.8010	C4—H4B	0.9700
K1—H2	2.8417	C5—C6	1.487 (4)
K1—B1	2.947 (3)	C5—H5A	0.9700
B1—H1	1.1500	C5—H5B	0.9700
B1—H2	1.1500	C6—H6A	0.9700
B1—H3	1.1500	C6—H6B	0.9700
B1—H4	1.1500	C7—C8	1.494 (4)
O1—C12	1.423 (3)	C7—H7A	0.9700
O1—C1	1.424 (3)	C7—H7B	0.9700
O2—C3	1.427 (3)	C8—H8A	0.9700
O2—C2	1.428 (3)	C8—H8B	0.9700
O3—C4	1.421 (3)	C9—C10	1.495 (4)
O3—C5	1.429 (3)	C9—H9A	0.9700
O4—C6	1.425 (3)	C9—H9B	0.9700
O4—C7	1.428 (3)	C10—H10A	0.9700
O5—C9	1.419 (3)	C10—H10B	0.9700
O5—C8	1.420 (3)	C11—C12	1.498 (3)
O6—C11	1.419 (3)	C11—H11A	0.9700
O6—C10	1.430 (3)	C11—H11B	0.9700
C1—C2	1.499 (4)	C12—H12A	0.9700
C1—H1A	0.9700	C12—H12B	0.9700
O3—K1—O1	117.04 (5)	H3A—C3—H3B	108.3
O3—K1—O5	117.58 (5)	O3—C4—C3	108.3 (2)
O1—K1—O5	117.45 (5)	O3—C4—H4A	110.0
O3—K1—O6	152.97 (5)	C3—C4—H4A	110.0
O1—K1—O6	59.38 (4)	O3—C4—H4B	110.0
O5—K1—O6	58.08 (5)	C3—C4—H4B	110.0
O3—K1—O4	59.76 (5)	H4A—C4—H4B	108.4
O1—K1—O4	157.17 (5)	O3—C5—C6	108.6 (2)
O5—K1—O4	58.10 (5)	O3—C5—H5A	110.0
O6—K1—O4	111.99 (5)	C6—C5—H5A	110.0
O3—K1—O2	59.26 (5)	O3—C5—H5B	110.0
O1—K1—O2	57.79 (5)	C6—C5—H5B	110.0
O5—K1—O2	151.93 (5)	H5A—C5—H5B	108.3
O6—K1—O2	110.64 (5)	O4—C6—C5	108.5 (2)
O4—K1—O2	114.15 (5)	O4—C6—H6A	110.0
H1—B1—H2	109.5	C5—C6—H6A	110.0
H1—B1—H3	109.5	O4—C6—H6B	110.0
H2—B1—H3	109.5	C5—C6—H6B	110.0
H1—B1—H4	109.5	H6A—C6—H6B	108.4
H2—B1—H4	109.5	O4—C7—C8	108.6 (2)
H3—B1—H4	109.5	O4—C7—H7A	110.0
C12—O1—C1	111.88 (17)	C8—C7—H7A	110.0
C12—O1—K1	119.14 (13)	O4—C7—H7B	110.0
C1—O1—K1	122.61 (14)	C8—C7—H7B	110.0
C3—O2—C2	111.58 (18)	H7A—C7—H7B	108.4
C3—O2—K1	110.05 (15)	O5—C8—C7	108.1 (2)
C2—O2—K1	109.21 (13)	O5—C8—H8A	110.1
C4—O3—C5	112.6 (2)	C7—C8—H8A	110.1
C4—O3—K1	121.06 (15)	O5—C8—H8B	110.1
C5—O3—K1	119.51 (14)	C7—C8—H8B	110.1
C6—O4—C7	112.15 (19)	H8A—C8—H8B	108.4
C6—O4—K1	103.99 (14)	O5—C9—C10	108.4 (2)
C7—O4—K1	109.86 (15)	O5—C9—H9A	110.0
C9—O5—C8	111.8 (2)	C10—C9—H9A	110.0
C9—O5—K1	120.02 (14)	O5—C9—H9B	110.0
C8—O5—K1	119.66 (14)	C10—C9—H9B	110.0
C11—O6—C10	111.04 (18)	H9A—C9—H9B	108.4
C11—O6—K1	106.64 (14)	O6—C10—C9	109.6 (2)
C10—O6—K1	113.12 (13)	O6—C10—H10A	109.8
O1—C1—C2	107.81 (19)	C9—C10—H10A	109.8
O1—C1—H1A	110.1	O6—C10—H10B	109.8
C2—C1—H1A	110.1	C9—C10—H10B	109.8
O1—C1—H1B	110.1	H10A—C10—H10B	108.2
C2—C1—H1B	110.1	O6—C11—C12	109.0 (2)
H1A—C1—H1B	108.5	O6—C11—H11A	109.9
O2—C2—C1	108.80 (19)	C12—C11—H11A	109.9
O2—C2—H2A	109.9	O6—C11—H11B	109.9
C1—C2—H2A	109.9	C12—C11—H11B	109.9
O2—C2—H2B	109.9	H11A—C11—H11B	108.3
C1—C2—H2B	109.9	O1—C12—C11	108.45 (19)
H2A—C2—H2B	108.3	O1—C12—H12A	110.0
O2—C3—C4	109.3 (2)	C11—C12—H12A	110.0
O2—C3—H3A	109.8	O1—C12—H12B	110.0
C4—C3—H3A	109.8	C11—C12—H12B	110.0
O2—C3—H3B	109.8	H12A—C12—H12B	108.4
C4—C3—H3B	109.8

(II) (borohydrido)(1,4,7,10,13,16-hexaoxa-2,3:11,12-dibenzocyclooctadeca- 2,11-diene-κ⁶O)(tetrahydrofuran)potassium

Crystal data

[K(BH4)(C4H8O)(C20H24O6)]	F(000) = 1040
Mr = 486.44	Dx = 1.290 Mg m^−3
Orthorhombic, P212121	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2ac 2ab	Cell parameters from 42072 reflections
a = 9.5611 (4) Å	θ = 3.0–25.7°
b = 9.9657 (5) Å	µ = 0.25 mm^−1
c = 26.2779 (15) Å	T = 100 K
V = 2503.8 (2) Å^3	Platelet, colourless
Z = 4	0.22 × 0.22 × 0.10 mm

Data collection

Nonius KappaCCD area-detector diffractometer	3880 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.060
Graphite monochromator	θmax = 25.7°, θmin = 3.0°
two ϕ and two ω scans with 2° steps	h = −11→11
42072 measured reflections	k = −12→12
4737 independent reflections	l = −31→32

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.048	H-atom parameters constrained
wR(F^2) = 0.129	w = 1/[σ^2(Fo^2) + (0.0789P)^2 + 0.4778P] where P = (Fo^2 + 2Fc^2)/3
S = 1.02	(Δ/σ)max = 0.001
4737 reflections	Δρmax = 0.37 e Å^−3
298 parameters	Δρmin = −0.25 e Å^−3
12 restraints	Absolute structure: Flack (1983), with how many Friedel pairs
Primary atom site location: structure-invariant direct methods	Absolute structure parameter: 0.08 (6)

Special details

Experimental. crystal-to-detector distance 40 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-hydrogen atoms were refined with anisotropic displacement parameters, with restraints for atoms C22 and C23 in the tetrahydrofuran molecule, which behave badly, likely due to unresolved disorder. The H atoms bound to B were found on a Fourier-difference map and all the other ones 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
K1	0.48320 (7)	0.28874 (6)	0.12717 (3)	0.02955 (19)
B1	0.2612 (4)	0.5003 (4)	0.12446 (17)	0.0352 (8)
H1	0.2050	0.4050	0.1106	0.042*
H2	0.3537	0.5235	0.0979	0.042*
H3	0.3018	0.4838	0.1652	0.042*
H4	0.1841	0.5889	0.1241	0.042*
O1	0.3288 (2)	0.0601 (2)	0.09697 (8)	0.0304 (5)
O2	0.4852 (2)	0.1739 (2)	0.02895 (8)	0.0304 (5)
O3	0.6682 (2)	0.3849 (2)	0.05380 (8)	0.0316 (5)
O4	0.7211 (2)	0.4336 (2)	0.15783 (8)	0.0295 (5)
O5	0.5908 (2)	0.2893 (2)	0.22632 (8)	0.0307 (5)
O6	0.3691 (2)	0.1171 (2)	0.19990 (8)	0.0319 (5)
O7	0.6876 (3)	0.1048 (2)	0.13417 (10)	0.0439 (6)
C1	0.3843 (3)	−0.0241 (3)	0.06053 (12)	0.0274 (7)
C2	0.4704 (3)	0.0372 (3)	0.02361 (12)	0.0275 (7)
C3	0.5325 (3)	−0.0385 (3)	−0.01418 (13)	0.0309 (7)
H3A	0.5891	0.0024	−0.0384	0.037*
C4	0.5096 (4)	−0.1772 (3)	−0.01577 (13)	0.0357 (8)
H4A	0.5519	−0.2290	−0.0409	0.043*
C5	0.4233 (3)	−0.2374 (3)	0.02030 (13)	0.0350 (8)
H5	0.4076	−0.3294	0.0190	0.042*
C6	0.3607 (4)	−0.1616 (3)	0.05822 (13)	0.0327 (8)
H6	0.3030	−0.2027	0.0821	0.039*
C7	0.5719 (4)	0.2405 (3)	−0.00785 (13)	0.0334 (8)
H7A	0.5294	0.2357	−0.0413	0.040*
H7B	0.6631	0.1981	−0.0094	0.040*
C8	0.5863 (4)	0.3842 (4)	0.00855 (12)	0.0333 (8)
H8A	0.6320	0.4364	−0.0178	0.040*
H8B	0.4949	0.4229	0.0150	0.040*
C9	0.6954 (4)	0.5164 (3)	0.07330 (13)	0.0323 (8)
H9A	0.6093	0.5578	0.0849	0.039*
H9B	0.7364	0.5726	0.0471	0.039*
C10	0.7954 (4)	0.4996 (3)	0.11698 (13)	0.0333 (8)
H10A	0.8750	0.4459	0.1065	0.040*
H10B	0.8292	0.5865	0.1282	0.040*
C11	0.8019 (3)	0.3878 (3)	0.19792 (12)	0.0296 (7)
C12	0.7325 (3)	0.3071 (3)	0.23376 (12)	0.0289 (7)
C13	0.8061 (4)	0.2527 (3)	0.27413 (13)	0.0324 (8)
H13	0.7612	0.1970	0.2974	0.039*
C14	0.9483 (4)	0.2820 (4)	0.27981 (14)	0.0389 (8)
H14	0.9979	0.2470	0.3072	0.047*
C15	1.0152 (4)	0.3630 (3)	0.24470 (14)	0.0378 (8)
H15	1.1096	0.3828	0.2488	0.045*
C16	0.9426 (3)	0.4151 (3)	0.20346 (13)	0.0331 (8)
H16	0.9886	0.4682	0.1796	0.040*
C17	0.5198 (4)	0.2058 (3)	0.26270 (12)	0.0339 (7)
H17A	0.5244	0.2456	0.2964	0.041*
H17B	0.5626	0.1176	0.2640	0.041*
C18	0.3708 (4)	0.1952 (4)	0.24542 (12)	0.0335 (8)
H18A	0.3144	0.1524	0.2715	0.040*
H18B	0.3328	0.2839	0.2389	0.040*
C19	0.2322 (3)	0.0975 (4)	0.17908 (12)	0.0315 (7)
H19A	0.1952	0.1815	0.1661	0.038*
H19B	0.1690	0.0636	0.2049	0.038*
C20	0.2481 (3)	−0.0027 (4)	0.13669 (12)	0.0320 (8)
H20A	0.2957	−0.0824	0.1489	0.038*
H20B	0.1570	−0.0288	0.1238	0.038*
C21	0.8195 (5)	0.0997 (5)	0.1091 (2)	0.0670 (14)
H21A	0.8954	0.1162	0.1328	0.080*
H21B	0.8242	0.1650	0.0818	0.080*
C22	0.8257 (5)	−0.0415 (6)	0.0885 (2)	0.0809 (16)
H22A	0.7901	−0.0454	0.0540	0.097*
H22B	0.9207	−0.0756	0.0890	0.097*
C23	0.7338 (5)	−0.1192 (5)	0.1243 (2)	0.0793 (15)
H23A	0.6602	−0.1651	0.1058	0.095*
H23B	0.7880	−0.1851	0.1430	0.095*
C24	0.6735 (5)	−0.0167 (4)	0.1596 (2)	0.0618 (13)
H24A	0.5758	−0.0357	0.1666	0.074*
H24B	0.7244	−0.0152	0.1916	0.074*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
K1	0.0320 (4)	0.0308 (3)	0.0258 (3)	−0.0017 (3)	0.0015 (3)	0.0012 (3)
B1	0.036 (2)	0.036 (2)	0.034 (2)	0.0040 (17)	−0.0013 (18)	−0.0024 (18)
O1	0.0369 (12)	0.0290 (11)	0.0252 (12)	−0.0062 (10)	0.0038 (10)	0.0001 (10)
O2	0.0381 (12)	0.0271 (11)	0.0260 (11)	−0.0038 (10)	0.0029 (10)	−0.0004 (9)
O3	0.0383 (12)	0.0279 (11)	0.0285 (12)	−0.0048 (10)	−0.0016 (10)	0.0011 (10)
O4	0.0292 (11)	0.0357 (12)	0.0235 (12)	−0.0038 (10)	0.0021 (9)	0.0017 (10)
O5	0.0290 (12)	0.0365 (12)	0.0266 (12)	−0.0044 (11)	0.0007 (9)	0.0019 (11)
O6	0.0289 (12)	0.0384 (13)	0.0284 (12)	−0.0058 (11)	0.0005 (10)	−0.0022 (10)
O7	0.0442 (14)	0.0381 (13)	0.0496 (16)	0.0042 (11)	0.0109 (13)	−0.0008 (13)
C1	0.0263 (15)	0.0312 (17)	0.0247 (18)	−0.0008 (14)	−0.0049 (14)	0.0003 (14)
C2	0.0289 (16)	0.0285 (16)	0.0251 (17)	0.0023 (14)	−0.0032 (14)	0.0013 (13)
C3	0.0287 (16)	0.0352 (18)	0.0287 (17)	−0.0037 (15)	−0.0017 (15)	0.0027 (14)
C4	0.0369 (18)	0.0343 (18)	0.0358 (18)	0.0025 (17)	−0.0024 (17)	−0.0067 (14)
C5	0.0392 (18)	0.0267 (17)	0.039 (2)	0.0025 (15)	−0.0077 (16)	0.0000 (15)
C6	0.0344 (18)	0.0314 (17)	0.0323 (19)	−0.0066 (15)	−0.0082 (15)	0.0034 (15)
C7	0.0419 (18)	0.0349 (19)	0.0234 (17)	−0.0043 (15)	0.0039 (14)	0.0006 (14)
C8	0.0405 (19)	0.0343 (18)	0.0250 (18)	−0.0088 (16)	0.0006 (15)	0.0048 (15)
C9	0.0409 (18)	0.0243 (16)	0.0317 (19)	−0.0044 (15)	0.0040 (15)	−0.0010 (14)
C10	0.0358 (18)	0.0268 (16)	0.037 (2)	−0.0041 (16)	0.0092 (16)	0.0009 (15)
C11	0.0289 (17)	0.0301 (16)	0.0299 (18)	0.0034 (15)	−0.0016 (14)	−0.0045 (15)
C12	0.0271 (16)	0.0269 (17)	0.0327 (18)	0.0015 (14)	0.0013 (14)	−0.0068 (15)
C13	0.0381 (19)	0.0297 (17)	0.0294 (18)	0.0046 (15)	0.0006 (15)	−0.0024 (14)
C14	0.041 (2)	0.0362 (18)	0.040 (2)	0.0077 (17)	−0.0070 (15)	−0.0036 (18)
C15	0.0291 (17)	0.0405 (19)	0.044 (2)	0.0048 (16)	−0.0024 (17)	−0.0071 (16)
C16	0.0328 (18)	0.0328 (18)	0.0336 (19)	−0.0007 (15)	0.0049 (14)	−0.0050 (15)
C17	0.0403 (18)	0.0375 (17)	0.0239 (16)	−0.0060 (18)	0.0032 (15)	0.0017 (14)
C18	0.0404 (18)	0.041 (2)	0.0190 (16)	−0.0046 (17)	0.0045 (14)	−0.0022 (15)
C19	0.0289 (16)	0.0399 (19)	0.0258 (17)	−0.0045 (16)	0.0024 (13)	−0.0004 (15)
C20	0.0338 (17)	0.0400 (19)	0.0222 (18)	−0.0089 (15)	0.0008 (15)	0.0054 (15)
C21	0.049 (2)	0.069 (3)	0.083 (3)	0.014 (2)	0.025 (2)	0.024 (3)
C22	0.059 (2)	0.115 (4)	0.068 (3)	0.035 (3)	−0.013 (2)	−0.039 (3)
C23	0.066 (3)	0.047 (2)	0.125 (4)	0.007 (2)	−0.035 (3)	−0.011 (3)
C24	0.050 (2)	0.057 (3)	0.079 (4)	0.005 (2)	−0.007 (2)	0.028 (2)

Geometric parameters (Å, º)

K1—O1	2.829 (2)	C7—H7A	0.9700
K1—O2	2.823 (2)	C7—H7B	0.9700
K1—O3	2.786 (2)	C8—H8A	0.9700
K1—O4	2.812 (2)	C8—H8B	0.9700
K1—O5	2.801 (2)	C9—C10	1.503 (5)
K1—O6	2.787 (2)	C9—H9A	0.9700
K1—O7	2.686 (3)	C9—H9B	0.9700
K1—B1	2.993 (4)	C10—H10A	0.9700
K1—H1	2.9331	C10—H10B	0.9700
K1—H2	2.7566	C11—C16	1.381 (5)
K1—H3	2.7899	C11—C12	1.405 (5)
B1—H1	1.1501	C12—C13	1.383 (5)
B1—H2	1.1501	C13—C14	1.399 (5)
B1—H3	1.1499	C13—H13	0.9300
B1—H4	1.1501	C14—C15	1.383 (5)
O1—C1	1.379 (4)	C14—H14	0.9300
O1—C20	1.441 (4)	C15—C16	1.387 (5)
O2—C2	1.376 (4)	C15—H15	0.9300
O2—C7	1.437 (4)	C16—H16	0.9300
O3—C8	1.424 (4)	C17—C18	1.499 (5)
O3—C9	1.431 (4)	C17—H17A	0.9700
O4—C11	1.384 (4)	C17—H17B	0.9700
O4—C10	1.446 (4)	C18—H18A	0.9700
O5—C12	1.380 (4)	C18—H18B	0.9700
O5—C17	1.438 (4)	C19—C20	1.504 (5)
O6—C18	1.427 (4)	C19—H19A	0.9700
O6—C19	1.432 (4)	C19—H19B	0.9700
O7—C24	1.390 (5)	C20—H20A	0.9700
O7—C21	1.424 (5)	C20—H20B	0.9700
C1—C6	1.390 (4)	C21—C22	1.508 (7)
C1—C2	1.411 (5)	C21—H21A	0.9700
C2—C3	1.381 (5)	C21—H21B	0.9700
C3—C4	1.400 (4)	C22—C23	1.503 (7)
C3—H3A	0.9300	C22—H22A	0.9700
C4—C5	1.392 (5)	C22—H22B	0.9700
C4—H4A	0.9300	C23—C24	1.496 (7)
C5—C6	1.386 (5)	C23—H23A	0.9700
C5—H5	0.9300	C23—H23B	0.9700
C6—H6	0.9300	C24—H24A	0.9700
C7—C8	1.502 (5)	C24—H24B	0.9700
O7—K1—O3	79.64 (7)	O3—C9—C10	106.7 (3)
O7—K1—O6	79.57 (7)	O3—C9—H9A	110.4
O3—K1—O6	159.06 (7)	C10—C9—H9A	110.4
O7—K1—O5	70.75 (8)	O3—C9—H9B	110.4
O3—K1—O5	114.18 (7)	C10—C9—H9B	110.4
O6—K1—O5	60.47 (6)	H9A—C9—H9B	108.6
O7—K1—O4	75.06 (7)	O4—C10—C9	107.7 (3)
O3—K1—O4	60.55 (6)	O4—C10—H10A	110.2
O6—K1—O4	115.79 (6)	C9—C10—H10A	110.2
O5—K1—O4	55.62 (6)	O4—C10—H10B	110.2
O7—K1—O2	77.35 (7)	C9—C10—H10B	110.2
O3—K1—O2	60.17 (6)	H10A—C10—H10B	108.5
O6—K1—O2	112.39 (7)	C16—C11—O4	124.0 (3)
O5—K1—O2	148.05 (7)	C16—C11—C12	120.1 (3)
O4—K1—O2	117.68 (7)	O4—C11—C12	115.8 (3)
O7—K1—O1	81.33 (7)	O5—C12—C13	123.9 (3)
O3—K1—O1	114.47 (6)	O5—C12—C11	116.2 (3)
O6—K1—O1	59.59 (6)	C13—C12—C11	119.9 (3)
O5—K1—O1	117.02 (7)	C12—C13—C14	119.6 (3)
O4—K1—O1	156.37 (7)	C12—C13—H13	120.2
O2—K1—O1	54.59 (6)	C14—C13—H13	120.2
H1—B1—H2	109.5	C15—C14—C13	120.0 (3)
H1—B1—H3	109.5	C15—C14—H14	120.0
H2—B1—H3	109.5	C13—C14—H14	120.0
H1—B1—H4	109.5	C14—C15—C16	120.5 (3)
H2—B1—H4	109.5	C14—C15—H15	119.7
H3—B1—H4	109.5	C16—C15—H15	119.7
C1—O1—C20	116.4 (2)	C11—C16—C15	119.7 (3)
C1—O1—K1	118.93 (18)	C11—C16—H16	120.1
C20—O1—K1	115.21 (18)	C15—C16—H16	120.1
C2—O2—C7	116.6 (2)	O5—C17—C18	106.7 (3)
C2—O2—K1	119.58 (18)	O5—C17—H17A	110.4
C7—O2—K1	115.59 (17)	C18—C17—H17A	110.4
C8—O3—C9	113.8 (3)	O5—C17—H17B	110.4
C8—O3—K1	103.14 (17)	C18—C17—H17B	110.4
C9—O3—K1	100.50 (18)	H17A—C17—H17B	108.6
C11—O4—C10	116.2 (2)	O6—C18—C17	107.6 (3)
C11—O4—K1	120.03 (18)	O6—C18—H18A	110.2
C10—O4—K1	114.73 (18)	C17—C18—H18A	110.2
C12—O5—C17	116.4 (2)	O6—C18—H18B	110.2
C12—O5—K1	119.51 (18)	C17—C18—H18B	110.2
C17—O5—K1	116.33 (17)	H18A—C18—H18B	108.5
C18—O6—C19	113.9 (2)	O6—C19—C20	106.3 (3)
C18—O6—K1	103.64 (17)	O6—C19—H19A	110.5
C19—O6—K1	100.34 (18)	C20—C19—H19A	110.5
C24—O7—C21	106.1 (3)	O6—C19—H19B	110.5
C24—O7—K1	123.8 (2)	C20—C19—H19B	110.5
C21—O7—K1	129.6 (2)	H19A—C19—H19B	108.7
O1—C1—C6	124.6 (3)	O1—C20—C19	107.6 (3)
O1—C1—C2	116.0 (3)	O1—C20—H20A	110.2
C6—C1—C2	119.4 (3)	C19—C20—H20A	110.2
O2—C2—C3	124.7 (3)	O1—C20—H20B	110.2
O2—C2—C1	114.7 (3)	C19—C20—H20B	110.2
C3—C2—C1	120.6 (3)	H20A—C20—H20B	108.5
C2—C3—C4	119.6 (3)	O7—C21—C22	103.6 (4)
C2—C3—H3A	120.2	O7—C21—H21A	111.0
C4—C3—H3A	120.2	C22—C21—H21A	111.0
C5—C4—C3	119.8 (3)	O7—C21—H21B	111.0
C5—C4—H4A	120.1	C22—C21—H21B	111.0
C3—C4—H4A	120.1	H21A—C21—H21B	109.0
C6—C5—C4	120.7 (3)	C23—C22—C21	103.5 (4)
C6—C5—H5	119.7	C23—C22—H22A	111.1
C4—C5—H5	119.7	C21—C22—H22A	111.1
C5—C6—C1	119.9 (3)	C23—C22—H22B	111.1
C5—C6—H6	120.0	C21—C22—H22B	111.1
C1—C6—H6	120.0	H22A—C22—H22B	109.0
O2—C7—C8	107.5 (3)	C24—C23—C22	105.2 (4)
O2—C7—H7A	110.2	C24—C23—H23A	110.7
C8—C7—H7A	110.2	C22—C23—H23A	110.7
O2—C7—H7B	110.2	C24—C23—H23B	110.7
C8—C7—H7B	110.2	C22—C23—H23B	110.7
H7A—C7—H7B	108.5	H23A—C23—H23B	108.8
O3—C8—C7	107.1 (3)	O7—C24—C23	105.0 (4)
O3—C8—H8A	110.3	O7—C24—H24A	110.7
C7—C8—H8A	110.3	C23—C24—H24A	110.7
O3—C8—H8B	110.3	O7—C24—H24B	110.7
C7—C8—H8B	110.3	C23—C24—H24B	110.7
H8A—C8—H8B	108.5	H24A—C24—H24B	108.8