Tricarbon­yl(η⁵-cyclo­penta­dien­yl)(trifluoro­hydroxy­borato)tungsten

The title compound, [W(C₅H₅)(HOBF₃)(CO)₃], has a four-legged piano-stool geometry which is typically found for C₅H₅W(CO)₃X complexes. The HOBF₃⁻ anion is the hydroly­sis product of BF₄⁻ and is coordinated via oxygen.

S1. Comment

[C₅H₅W(CO)₃]BF₄ was first described by Beck et al. (1978) and used as a reactive intermediate (Werner et al., 1987). All attempts to crystallize [C₅H₅W(CO)₃]BF₄ for X-ray diffraction failed and the compound was described as extremely sensitive towards hydrolysis (Appel et al., 1987; Beck et al.,1989). We were able to obtain crystals of the first reaction product in the hydrolytic process that has been described before for (CO)₅ReFBF₃ (Raab et al., 1981).

The HOBF₃ ligand is coordinated through the oxygen atom. The W—O distance of 2.155 (3) Å is significantly shorter than the W—O distance for coordinated water in (CO)₃(P-ⁱPr₃)₂WOH₂ of 2.320 (5) Å (Kubas et al., 1992) and even shorter than the W—O distance for coordinated water in H₂(η¹-O₂CBu^t)₂(PMe₃)₃WOH₂ of 2.224 (2) Å (Zhu et al., 2005). It is in the same range with [as] the coordinated HOBF₃^- anion in (CO)₅ReO(H)BF₃ with an Re—O distance of 2.167 Å (Beck et al., 1986). The HOBF₃ ligands of the title compound interact via an O—H···F hydrogen bond. In an initial structure model a weakly coordinating BF₄^- anion was assumed rather than the hydrolysis product HOBF₃^-. After convergence of the refinement at apparently convincing agreement factors, however, both the B—F distance and the displacement parameters (see Refinement) indicated that the atom bridging W and B could be better refined as oxygen. Its distance to boron [1.485 (5) Å] was significantly longer than B—F distances found in the Cambridge Structural Database (CSD; Allen, 2002) for tetrafluoroborate anions bound to metal centres via F [1.398 (23) Å] as observed for example in [CuL₂O(H)BF₃][BF₄] [where L = ligand?] containing both types of ligands discussed (Onggo et al., 1991). In the correct model, the B1—O4 distance [1.474 (5) Å] is nearly the same as the B—O distance in (CO)₅ReO(H)BF₃ (1.476 Å) (Beck et al., 1986)_. Infrared spectra of the bulk material show a broad ν(OH) band, indicating that the crystallizing product is only C₅H₅W(CO)₃O(H)BF₃. For the cyclopentadienyl ligand a slip distortion (distance of the tungsten atom projection on the ring plane from the ring centre of gravity) of 0.106 Å with shorter metal–carbon bonds to C1, C5 and longer distances W—C2, –C3, –C4 is observed. The cyclopentadienyl ligand is tilted due to the strong trans effect of the CO ligands as described earlier for [Et₄N] [C₅H₅Mo(CO)₂(η²-O₂CO)] (Curtis & Han, 1985) and [C₅H₅TaCl₂(CO)₂(THF)] [THF = tetrahydrofuran?] (Kwon & Curtis, 1990). This effect has also been explained theoretically (Chinn et al., 1983).

Related literature

For related literature, see: Appel et al. (1987); Beck & Schloter (1978); Beck et al. (1986, 1989); Chinn & Hall (1983); Curtis & Han (1985); Hirshfeld (1976); Kubas et al. (1992); Kwon & Curtis (1990); Onggo et al. (1991); Raab et al. (1981); Spek (2009); Werner et al. (1987).

S2. Experimental

The synthesis was carried out by the reaction of Cp(CO)₃WCH₃ with HBF₄^.OEt₂ (1:2 molar ratio) in CH₂Cl₂ for 30 min at 253 K. A deep red solution was formed immediately. The solvent was reduced at room temperature and red–orange crystals suitable for X-ray diffraction formed in 20% yield. The melting point is 407 K (decomp.). IR (ATR, cm^-1): CO ligands: 2083 (s), 2017 (s), 1969 (s); HOBF₃^- anion: 3401 (br),1083 (m).

S3. Refinement

In an initial structure model a weakly coordinated BF₄^- anion was assumed rather than the hydolysis product HOBF₃^-_. After convergence of the refinement at apparently convincing agreement factors, however, both the B1—F distance and displacement parameters show that the atom X bridging W and B could be better refined as oxygen. In the initial tetrafluoroborate model, the B—X distance of 1.485 (5) Å was significantly longer than the B—F distances found in the CSD for tetrafluoroborate anions bonded to metals by F [metal-F—BF₃ 1.398 (23) Å], and much longer than the terminal B—F distances [1.370 (31) Å]. When X was refined as fluorine, a displacement parameter significantly larger than expected was obtained [U_iso(W1) = 0.01394 (6), U_iso(X) = 0.0374 (7) and U_iso(B1) = 0.0226 (10)], and two rigid-bond alerts were obtained in connection to these displacement parameters (Spek, 2009): PLAT230_ALERT_2_C Hirshfeld Test Diff for F – B1.. 6.63 su PLAT232_ALERT_2_C Hirshfeld Test Diff (M—X) W1 – F.. 9.52 su.

According to the rigid-bond postulate, the components of the anisotropic displacement parameters along chemical bonds are assumed to be equal in magnitude. Large differences supposedly indicate contamination of these parameters with other effects. Atomic sites assigned the wrong scattering type (e.g. Ag versus Br) should generate 'problem signals' with this test (Hirshfeld, 1976).

After correctly assigning the atomic scattering factor for O to X, the following results were obtained: (a) the displacement parameter for X became unexceptional [U_iso(X) = 0.0217 (6)]; (b) a local electron-density maximum, peak no. 5, represented the missing hydroxyl H atom; free refinement of this atom resulted in reasonable geometry and an intermolecular hydrogen bond; (c) agreement factors R and wR2 improved (0.0201 versus. 0.0208; 0.043 versus 0.046); (d) the distance pattern became normal for HOBF₃ coordinated to metal [in the CSD, the average d(B—O) amounts to 1.472 Å]; and (e) the above-mentioned rigid-bond alerts disappeared.

The Cp hydrogen atoms were refined in calculated positions, riding on carbon atoms, but the OH hydrogen was located in the difference Fourier map, and refined freely.

Computing details

Data collection: SMART (Bruker, 2000); cell refinement: SAINT-Plus (Bruker, 2000); data reduction: SAINT-Plus (Bruker, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: XP in SHELXTL (Sheldrick, 2008); software used to prepare material for publication: XCIF in SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level.
	Fig. 2. View of the interactions of anions via hydrogen bonding. [Symmetry codes: (i) -x + 3/2, y + 1/2, -z + 3/2; (ii) x, y + 1, z; (iii) -x + 3/2, y - 1/2, -z + 3/2.]

Tricarbonyl(η⁵-cyclopentadienyl)(trifluorohydroxyborato)tungsten

Crystal data

[W(C5H5)(HOBF3)(CO)3]	F(000) = 768
Mr = 417.79	Dx = 2.648 Mg m^−3
Monoclinic, P21/n	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2yn	Cell parameters from 930 reflections
a = 10.7679 (17) Å	θ = 2–29°
b = 8.5489 (14) Å	µ = 11.07 mm^−1
c = 11.4313 (18) Å	T = 100 K
β = 95.297 (2)°	Irregular block, orange
V = 1047.8 (3) Å^3	0.14 × 0.12 × 0.06 mm
Z = 4

Data collection

Bruker SMART APEX CCD diffractometer	2507 independent reflections
Radiation source: normal-focus sealed tube	2289 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.025
Detector resolution: 8.26 pixels mm^-1	θmax = 28.5°, θmin = 2.5°
ω rotations with narrow frames scans	h = −14→14
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	k = −11→11
Tmin = 0.345, Tmax = 0.437	l = −14→15
12253 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.020	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.043	H atoms treated by a mixture of independent and constrained refinement
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0222P)^2] where P = (Fo^2 + 2Fc^2)/3
2507 reflections	(Δ/σ)max = 0.005
158 parameters	Δρmax = 1.15 e Å^−3
0 restraints	Δρmin = −0.74 e Å^−3

Special details

Experimental. SADABS method is based on the method of Blessing: Blessing, R. H., Acta Crystallogr., Sect. A 1995, 51, 33.

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Refinement. Refinement of F² against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F², conventional R-factors R are based on F, with F set to zero for negative F². The threshold expression of F² > σ(F²) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F² are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger.

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

	x	y	z	Uiso*/Ueq
W1	0.779847 (12)	0.196639 (16)	1.020381 (12)	0.01404 (5)
O1	0.9820 (2)	0.0660 (3)	1.2103 (2)	0.0271 (6)
O2	1.0322 (3)	0.2772 (3)	0.9132 (2)	0.0284 (6)
O3	0.7076 (3)	−0.1585 (3)	1.0379 (3)	0.0265 (6)
O4	0.7197 (3)	0.1717 (3)	0.8363 (2)	0.0217 (6)
H6	0.749 (5)	0.238 (6)	0.802 (4)	0.041 (16)*
F1	0.6827 (2)	−0.0869 (3)	0.7783 (2)	0.0377 (6)
F2	0.5229 (2)	0.0603 (3)	0.8310 (2)	0.0341 (6)
F3	0.6065 (2)	0.1127 (3)	0.65959 (19)	0.0297 (5)
B1	0.6304 (4)	0.0628 (5)	0.7739 (4)	0.0225 (9)
C1	0.7713 (3)	0.4020 (4)	1.1458 (3)	0.0204 (8)
H1	0.8447	0.4356	1.1914	0.024*
C2	0.7261 (4)	0.4588 (4)	1.0334 (3)	0.0228 (8)
H2	0.7642	0.5367	0.9894	0.027*
C3	0.6142 (4)	0.3788 (5)	0.9990 (3)	0.0260 (9)
H3	0.5638	0.3950	0.9273	0.031*
C4	0.5885 (4)	0.2713 (5)	1.0864 (4)	0.0245 (9)
H4	0.5190	0.2027	1.0848	0.029*
C5	0.6865 (4)	0.2850 (4)	1.1779 (3)	0.0208 (8)
H5	0.6942	0.2261	1.2487	0.025*
C6	0.9082 (3)	0.1145 (4)	1.1418 (3)	0.0197 (8)
C7	0.9415 (4)	0.2416 (5)	0.9504 (3)	0.0212 (8)
C8	0.7382 (3)	−0.0317 (5)	1.0250 (3)	0.0197 (8)

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
W1	0.01404 (8)	0.01421 (8)	0.01400 (8)	0.00126 (6)	0.00207 (5)	−0.00105 (6)
O1	0.0260 (15)	0.0255 (15)	0.0280 (15)	0.0018 (12)	−0.0065 (12)	0.0030 (12)
O2	0.0218 (15)	0.0369 (17)	0.0277 (16)	0.0006 (13)	0.0095 (12)	0.0013 (13)
O3	0.0266 (15)	0.0201 (15)	0.0319 (16)	−0.0020 (12)	−0.0023 (12)	−0.0025 (12)
O4	0.0281 (15)	0.0207 (15)	0.0164 (14)	−0.0021 (12)	0.0026 (11)	−0.0006 (11)
F1	0.0532 (16)	0.0248 (13)	0.0332 (14)	0.0098 (12)	−0.0060 (12)	−0.0077 (11)
F2	0.0266 (13)	0.0465 (16)	0.0293 (13)	−0.0090 (11)	0.0030 (10)	−0.0034 (11)
F3	0.0327 (13)	0.0344 (14)	0.0209 (12)	0.0009 (11)	−0.0026 (10)	−0.0031 (10)
B1	0.025 (2)	0.023 (2)	0.019 (2)	−0.0001 (18)	0.0002 (17)	−0.0034 (17)
C1	0.0205 (18)	0.0179 (19)	0.023 (2)	0.0009 (15)	0.0037 (15)	−0.0080 (16)
C2	0.031 (2)	0.0126 (18)	0.026 (2)	0.0033 (16)	0.0124 (16)	0.0033 (15)
C3	0.027 (2)	0.026 (2)	0.024 (2)	0.0178 (18)	−0.0020 (16)	−0.0046 (17)
C4	0.0161 (19)	0.023 (2)	0.035 (2)	0.0005 (16)	0.0069 (16)	−0.0084 (17)
C5	0.024 (2)	0.022 (2)	0.0179 (19)	0.0056 (16)	0.0082 (15)	−0.0023 (15)
C6	0.0195 (19)	0.0172 (19)	0.023 (2)	−0.0041 (15)	0.0044 (15)	−0.0037 (15)
C7	0.020 (2)	0.024 (2)	0.020 (2)	0.0034 (16)	0.0008 (16)	−0.0018 (16)
C8	0.0207 (18)	0.022 (2)	0.0161 (18)	0.0023 (16)	−0.0019 (14)	−0.0026 (15)

Geometric parameters (Å, º)

W1—C6	1.994 (4)	F1—B1	1.397 (5)
W1—C8	2.005 (4)	F2—B1	1.380 (5)
W1—C7	2.018 (4)	F3—B1	1.376 (5)
W1—O4	2.155 (3)	C1—C2	1.417 (5)
W1—C5	2.271 (4)	C1—C5	1.425 (5)
W1—C1	2.274 (3)	C1—H1	0.9500
W1—C2	2.323 (4)	C2—C3	1.410 (6)
W1—C4	2.347 (4)	C2—H2	0.9500
W1—C3	2.363 (4)	C3—C4	1.404 (6)
O1—C6	1.141 (4)	C3—H3	0.9500
O2—C7	1.142 (4)	C4—C5	1.420 (5)
O3—C8	1.146 (4)	C4—H4	0.9500
O4—B1	1.474 (5)	C5—H5	0.9500
O4—H6	0.77 (5)
C6—W1—C8	77.36 (15)	F3—B1—F2	111.2 (3)
C6—W1—C7	77.01 (15)	F3—B1—F1	111.0 (3)
C8—W1—C7	113.53 (15)	F2—B1—F1	108.8 (3)
C6—W1—O4	140.50 (13)	F3—B1—O4	108.7 (3)
C8—W1—O4	83.21 (13)	F2—B1—O4	108.6 (3)
C7—W1—O4	79.86 (13)	F1—B1—O4	108.5 (3)
C6—W1—C5	83.93 (14)	C2—C1—C5	107.4 (3)
C8—W1—C5	100.74 (14)	C2—C1—W1	74.0 (2)
C7—W1—C5	135.39 (15)	C5—C1—W1	71.6 (2)
O4—W1—C5	133.82 (12)	C2—C1—H1	126.3
C6—W1—C1	84.18 (14)	C5—C1—H1	126.3
C8—W1—C1	135.46 (14)	W1—C1—H1	120.0
C7—W1—C1	100.93 (14)	C3—C2—C1	107.5 (3)
O4—W1—C1	131.79 (12)	C3—C2—W1	74.0 (2)
C5—W1—C1	36.54 (13)	C1—C2—W1	70.1 (2)
C6—W1—C2	117.12 (15)	C3—C2—H2	126.3
C8—W1—C2	151.65 (15)	C1—C2—H2	126.3
C7—W1—C2	94.06 (15)	W1—C2—H2	121.3
O4—W1—C2	95.97 (12)	C4—C3—C2	109.8 (4)
C5—W1—C2	59.81 (13)	C4—C3—W1	72.0 (2)
C1—W1—C2	35.89 (13)	C2—C3—W1	71.0 (2)
C6—W1—C4	116.40 (15)	C4—C3—H3	125.1
C8—W1—C4	92.92 (14)	C2—C3—H3	125.1
C7—W1—C4	152.91 (16)	W1—C3—H3	123.5
O4—W1—C4	98.49 (13)	C3—C4—C5	106.8 (3)
C5—W1—C4	35.77 (14)	C3—C4—W1	73.3 (2)
C1—W1—C4	59.96 (13)	C5—C4—W1	69.2 (2)
C2—W1—C4	59.05 (14)	C3—C4—H4	126.6
C6—W1—C3	140.56 (14)	C5—C4—H4	126.6
C8—W1—C3	118.39 (15)	W1—C4—H4	122.6
C7—W1—C3	120.24 (15)	C4—C5—C1	108.6 (3)
O4—W1—C3	78.93 (12)	C4—C5—W1	75.0 (2)
C5—W1—C3	58.54 (13)	C1—C5—W1	71.8 (2)
C1—W1—C3	58.85 (13)	C4—C5—H5	125.7
C2—W1—C3	35.01 (14)	C1—C5—H5	125.7
C4—W1—C3	34.68 (14)	W1—C5—H5	119.2
B1—O4—W1	131.2 (2)	O1—C6—W1	179.1 (3)
B1—O4—H6	120 (4)	O2—C7—W1	175.4 (3)
W1—O4—H6	109 (4)	O3—C8—W1	172.7 (3)
C6—W1—O4—B1	88.3 (4)	O4—W1—C3—C4	123.2 (2)
C8—W1—O4—B1	27.6 (3)	C5—W1—C3—C4	−38.1 (2)
C7—W1—O4—B1	143.1 (3)	C1—W1—C3—C4	−81.1 (3)
C5—W1—O4—B1	−70.7 (3)	C2—W1—C3—C4	−119.2 (3)
C1—W1—O4—B1	−121.3 (3)	C6—W1—C3—C2	61.0 (3)
C2—W1—O4—B1	−123.8 (3)	C8—W1—C3—C2	166.4 (2)
C4—W1—O4—B1	−64.3 (3)	C7—W1—C3—C2	−46.4 (3)
C3—W1—O4—B1	−93.1 (3)	O4—W1—C3—C2	−117.6 (2)
W1—O4—B1—F3	168.7 (2)	C5—W1—C3—C2	81.1 (2)
W1—O4—B1—F2	47.6 (4)	C1—W1—C3—C2	38.1 (2)
W1—O4—B1—F1	−70.5 (4)	C4—W1—C3—C2	119.2 (3)
C6—W1—C1—C2	157.3 (2)	C2—C3—C4—C5	0.2 (4)
C8—W1—C1—C2	−137.4 (2)	W1—C3—C4—C5	61.5 (3)
C7—W1—C1—C2	81.7 (2)	C2—C3—C4—W1	−61.3 (3)
O4—W1—C1—C2	−4.4 (3)	C6—W1—C4—C3	142.9 (2)
C5—W1—C1—C2	−115.1 (3)	C8—W1—C4—C3	−139.7 (2)
C4—W1—C1—C2	−77.6 (2)	C7—W1—C4—C3	28.1 (4)
C3—W1—C1—C2	−37.1 (2)	O4—W1—C4—C3	−56.2 (2)
C6—W1—C1—C5	−87.7 (2)	C5—W1—C4—C3	115.9 (3)
C8—W1—C1—C5	−22.3 (3)	C1—W1—C4—C3	77.6 (2)
C7—W1—C1—C5	−163.2 (2)	C2—W1—C4—C3	35.7 (2)
O4—W1—C1—C5	110.7 (2)	C6—W1—C4—C5	27.0 (3)
C2—W1—C1—C5	115.1 (3)	C8—W1—C4—C5	104.4 (2)
C4—W1—C1—C5	37.5 (2)	C7—W1—C4—C5	−87.8 (4)
C3—W1—C1—C5	78.0 (2)	O4—W1—C4—C5	−172.1 (2)
C5—C1—C2—C3	0.9 (4)	C1—W1—C4—C5	−38.3 (2)
W1—C1—C2—C3	65.2 (3)	C2—W1—C4—C5	−80.2 (2)
C5—C1—C2—W1	−64.3 (2)	C3—W1—C4—C5	−115.9 (3)
C6—W1—C2—C3	−141.4 (2)	C3—C4—C5—C1	0.4 (4)
C8—W1—C2—C3	−25.8 (4)	W1—C4—C5—C1	64.5 (2)
C7—W1—C2—C3	141.1 (2)	C3—C4—C5—W1	−64.1 (3)
O4—W1—C2—C3	60.9 (2)	C2—C1—C5—C4	−0.8 (4)
C5—W1—C2—C3	−77.2 (2)	W1—C1—C5—C4	−66.6 (3)
C1—W1—C2—C3	−115.8 (3)	C2—C1—C5—W1	65.8 (2)
C4—W1—C2—C3	−35.4 (2)	C6—W1—C5—C4	−155.8 (2)
C6—W1—C2—C1	−25.6 (3)	C8—W1—C5—C4	−80.0 (2)
C8—W1—C2—C1	90.0 (4)	C7—W1—C5—C4	139.6 (3)
C7—W1—C2—C1	−103.1 (2)	O4—W1—C5—C4	10.9 (3)
O4—W1—C2—C1	176.7 (2)	C1—W1—C5—C4	115.8 (3)
C5—W1—C2—C1	38.6 (2)	C2—W1—C5—C4	77.9 (2)
C4—W1—C2—C1	80.4 (2)	C3—W1—C5—C4	36.9 (2)
C3—W1—C2—C1	115.8 (3)	C6—W1—C5—C1	88.4 (2)
C1—C2—C3—C4	−0.7 (4)	C8—W1—C5—C1	164.3 (2)
W1—C2—C3—C4	61.9 (3)	C7—W1—C5—C1	23.9 (3)
C1—C2—C3—W1	−62.6 (2)	O4—W1—C5—C1	−104.8 (2)
C6—W1—C3—C4	−58.2 (3)	C2—W1—C5—C1	−37.9 (2)
C8—W1—C3—C4	47.2 (3)	C4—W1—C5—C1	−115.8 (3)
C7—W1—C3—C4	−165.6 (2)	C3—W1—C5—C1	−78.9 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O4—H6···F1^i	0.77 (5)	1.94 (5)	2.708 (4)	177 (6)

Symmetry code: (i) −x+3/2, y+1/2, −z+3/2.