Redetermination of the structure of diferrocenyl ketone at low temperature

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Acta Cryst.(2003). E59, m33±m35 DOI: 10.1107/S1600536802022262 Natalie Bratychet al. [Fe₂(C₅H₅)₂(C₁₁H₈O)]

m33

metal-organic papers

Acta Crystallographica Section E Structure Reports Online

ISSN 1600-5368

Redetermination of the structure of

diferrocenyl ketone at low temperature

Natalie Bratych, Kathryn Hassall and Jonathan White*

School of Chemistry, University of Melbourne, Parkville, Victoria 3010, Australia

Correspondence e-mail: [email protected]

Key indicators Single-crystal X-ray study T= 130 K

Mean(C±C) = 0.003 AÊ Rfactor = 0.034 wRfactor = 0.094

Data-to-parameter ratio = 12.3

For details of how these key indicators were automatically derived from the article, see http://journals.iucr.org/e.

The structure of diferrocenyl ketone, [Fe2(C5H5)2(C11H8O)],

was redetermined as part of our investigations of carbon±iron hyperconjugation. The title ketone lies on a twofold axis of symmetry. Lengthening of the carbonyl C O bond [1.237 (3) AÊ compared with that expected for simple ketones, 1.210 AÊ] and slight slippage of the Fe atom towards the carbonyl carbon are consistent with the presence of strong hyperconjugation of the carbonyl group with the adjacent FeÐC bond. The structure was determined at 130 K.

Comment

The title compound, (1), is an intermediate in the synthesis of the-silyl-substituted diferrocenyl cation (2).

Upon full characterization of (1), we observed that the IR carbonyl-stretching frequency of (1), 1609 cmÿ1_{, was very low}

for a ketone; normally values lie in the range 1650±1750 cmÿ1_.

Futhermore, the 13_{C NMR chemical shift occurred at}

199 p.p.m., which is at a high ®eld for a typical ketone carbon. The low stretching frequency in the IR spectrum, and the high-®eld resonance in the 13_{C NMR implied that the resonance}

form (1a) (Fig. 1) was making a signi®cant contribution to the ground state structure of (1). The resonance form (1a) is

Received 20 November 2002 Accepted 2 December 2002 Online 24 December 2002

Figure 1

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metal-organic papers

m34

Natalie Bratychet al. [Fe₂(C₅H₅)₂(C₁₁H₈O)] Acta Cryst.(2003). E59, m33±m35 presumably stabilized by hyperconjugation with the carbon±

iron bonds of the two attached ferrocenyl substituents. Our interest in the structural effects of carbon±metal hyperconju-gation (Poolet al., 1998; Chanet al., 1996; White & Robertson, 1992; Whiteet al., 2000), we determined the structure of (1) at low temperature to establish whether there were any signi®-cant structural effects consistent with hyperconjugation between the ferrocenyl substituents and the carbonyl group. A previous room-temperature determination of the structure of (1) (Trotter & Macdonald, 1966) was not deemed suf®ciently precise for our requirements.

The ketone group of (1) lies on a crystallographic twofold axis of symmetry. The attached ferrocenyl substituents are slightly twisted from coplanarity with the ketone carbonyl [C5ÐC1ÐC11ÐO1 =ÿ17.7 (2)_{], a conformation which is a}

compromise between maximizing hyperconjugation of the carbonyl group with the ferrocenyl substituents [the Fe1Ð C1ÐC11ÐO1 dihedral angle is 105.4 (1)_{, whereas maximum}

overlap occurs when this angle is 90_{], and minimizing}

non-bonded repulsions involving the C2 and C5 H atoms on each ferrocenyl substituent with the second ferrocenyl substituent and the carbonyl O atom. The carbonyl bond distance (C11Ð O1) is 1.237 (3) AÊ, which is signi®cantly longer than a typical ketone carbonyl, 1.210 AÊ (Allenet al., 1987). There are also some interesting differences in the FeÐCp bond distances in the substituted cyclopentadienyl ring (Table 1). These distances show that the Fe atom has slipped slightly toward the carbonyl-bearing carbon (C1); by contrast there are no signi®cant differences in the FeÐCp distances in the unsub-stituted cyclopentadienyl ring, which is, in addition, essentially parallel to the substituted cyclopentadienyl [angle between the planes de®ned by C1ÐC5 and C6ÐC10 is 1.8 (1)_{]. The}

slipping of Fe1 towards C1 presumably occurs to maximize the overlap between the Fe1ÐC1 bond and the carbonylorbital.

Experimental

The title compound was prepared according to the reactionScheme. Thus, ferrocene was converted into lithioferrocene by treatment with tert-butyllithium and potassium tert-butoxide in tetrahydrofuran. Reaction with N-(dimethylamino)chlorocarbamate afforded (1) in 55% yield. Crystals of (1) were grown from pentane.

Crystal data

[Fe2(C5H5)2(C11H8O)]

Mr= 398.05

Monoclinic,P2=c a= 10.4058 (11) AÊ

b= 6.1448 (7) AÊ

c= 12.9773 (14) AÊ

= 110.835 (2) V= 775.53 (15) AÊ3

Z= 2

Dx= 1.705 Mg mÿ3

MoKradiation Cell parameters from 2038

re¯ections

= 3.3±28.8 = 1.87 mmÿ1

T= 130.0 (2) K Rod, red

0.350.150.10 mm

Data collection

Bruker SMART CCD area-detector diffractometer

'and!scans

Absorption correction: multi-scan (SADABS; Blessing, 1995; Shel-drick, 2001)

Tmin= 0.86,Tmax= 1.0

3879 measured re¯ections

1368 independent re¯ections 1228 re¯ections withI> 2(I)

Rint= 0.078

max= 25.0

h=ÿ12!12

k=ÿ7!4

l=ÿ14!15

Re®nement

Re®nement onF2

R[F2_{> 2}₍_F2_{)] = 0.034}

wR(F2_{) = 0.094}

S= 1.02 1368 re¯ections 111 parameters

H atoms treated by a mixture of independent and constrained re®nement

w= 1/[2₍_F

o2) + (0.0614P)2]

whereP= (Fo2+ 2Fc2)/3

(/)max= 0.001

max= 0.80 e AÊÿ3

min=ÿ0.46 e AÊÿ3

Extinction correction:SHELXL97 (Sheldrick, 1997

Extinction coef®cient: 0.007 (2)

Table 1

Selected geometric parameters (AÊ,_).

C1ÐC5 1.424 (3) C1ÐC2 1.444 (3) C1ÐC11 1.477 (2) C1ÐFe1 2.0344 (19) C2ÐC3 1.411 (3) C2ÐFe1 2.039 (2) C3ÐC4 1.427 (3) C3ÐFe1 2.052 (2) C4ÐC5 1.418 (3) C4ÐFe1 2.056 (2) C5ÐFe1 2.0495 (19)

C6ÐC7 1.413 (3) C6ÐC10 1.420 (3) C6ÐFe1 2.046 (3) C7ÐC8 1.422 (3) C7ÐFe1 2.045 (2) C8ÐC9 1.418 (3) C8ÐFe1 2.045 (3) C9ÐC10 1.412 (3) C9ÐFe1 2.043 (2) C10ÐFe1 2.038 (2) C11ÐO1 1.237 (3) C5ÐC1ÐC11 122.32 (17)

C2ÐC1ÐC11 130.15 (18) C11ÐC1ÐFe1 125.69 (12)

O1ÐC11ÐC1 118.37 (12) C1ÐFe1ÐC10 124.53 (9)

C5ÐC1ÐC11ÐO1 ÿ17.7 (2)

C2ÐC1ÐC11ÐO1 162.34 (17) Fe1ÐC1ÐC11ÐO1Fe1ÐC1ÐC11ÐC1i ÿ105.38 (13)_{74.62 (13)}

Symmetry code: (i) 1ÿx;y;1 2ÿz.

H atoms were ®xed in idealized positions.

Data collection:SMART(Bruker, 2000); cell re®nement:SMART; data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXTL (Bruker, 1997); program(s) used to re®ne structure:SHELXTL; molecular graphics:SHELXTL; software used to prepare material for publication:SHELXTL.

The authors acknowledge support from the ACS Petroleum Research Fund and the University of Melbourne.

References

Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987).J. Chem. Soc. Perkin Trans.2, pp. S1±19.

Blessing, R. H. (1995).Acta Cryst.A51, 33±38.

Figure 2

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Bruker (1997). SHELXTL. Version 5.10. Bruker AXS Inc., Madison, Wisconsin, USA.

Bruker (1999).SAINT. Version 6.02. Bruker AXS Inc., Madison, Wisconsin, USA.

Bruker (2000).SMART. Version 5.55. Bruker AXS Inc., Madison, Wisconsin, USA.

Chan, V. Y., Clark, C. I., Giordano, J., Green, A. J., Karalis, A. & White, J. M. (1996).J. Org. Chem.61, 5227±5233.

Pool, B. R., Sun, C.-C. & White, J. M. (1998).J. Chem. Soc. Dalton Trans.pp. 1269±1271.

Sheldrick, G. M. (2001).SADABS. Version 2.03. University of GoÈttingen, Germany.

Trotter, J. & Macdonald, A. C. (1966).Acta Cryst.21, 359.

White, J. M. Giordano, J. & Green, A. J. (2000). Aust. J. Chem.53, 285± 292.

White, J. M. & Robertson, G. B. (1992).J. Org. Chem.57, 4638±4644.

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sup-1 Acta Cryst. (2003). E59, m33–m35

supporting information

Acta Cryst. (2003). E59, m33–m35 [https://doi.org/10.1107/S1600536802022262]

Redetermination of the structure of diferrocenyl ketone at low temperature

Natalie Bratych, Kathryn Hassall and Jonathan White

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Crystal data

[Fe2(C5H5)2(C11H8O)] Mr = 398.05

Monoclinic, P2/c Hall symbol: -P 2yc a = 10.4058 (11) Å b = 6.1448 (7) Å c = 12.9773 (14) Å β = 110.835 (2)° V = 775.53 (15) Å3 Z = 2

F(000) = 408 Dx = 1.705 Mg m−3 Melting point: 211.5 K

Mo Kα radiation, λ = 0.71073 Å Cell parameters from 2038 reflections θ = 3.3–28.8°

µ = 1.87 mm−1 T = 130 K Rod, red

0.35 × 0.15 × 0.10 mm

Data collection

Bruker SMART CCD area-detector diffractometer

Radiation source: fine-focus sealed tube Graphite monochromator

φ and ω scans

Absorption correction: multi-scan

(SADABS; Blessing, 1995; Sheldrick, 2001) Tmin = 0.86, Tmax = 1.0

3879 measured reflections 1368 independent reflections 1228 reflections with I > 2σ(I) Rint = 0.078

θmax = 25.0°, θmin = 2.1° h = −12→12

k = −7→4 l = −14→15

Refinement Refinement on F2 Least-squares matrix: full R[F2_{> 2}_σ₍_F2_{)] = 0.034} wR(F2_{) = 0.094} S = 1.02 1368 reflections 111 parameters 0 restraints

Primary atom site location: structure-invariant direct methods

Secondary atom site location: difference Fourier map

Hydrogen site location: inferred from neighbouring sites

H atoms treated by a mixture of independent and constrained refinement

w = 1/[σ2₍_F

o2) + (0.0614P)2] where P = (Fo2 + 2Fc2)/3 (Δ/σ)max = 0.001

Δρmax = 0.80 e Å−3 Δρmin = −0.46 e Å−3

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Special details

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 (Å2₎

x y z Uiso*/Ueq

C1 0.6301 (2) 0.1018 (3) 0.26450 (16) 0.0192 (5) C2 0.6544 (2) 0.3244 (4) 0.24073 (17) 0.0213 (5) H2 0.5863 0.4330 0.2109 0.026* C3 0.7976 (2) 0.3511 (4) 0.26977 (17) 0.0227 (5) H3 0.8425 0.4815 0.2623 0.027* C4 0.8639 (2) 0.1499 (4) 0.31219 (17) 0.0235 (5) H4 0.9601 0.1235 0.3386 0.028* C5 0.7603 (2) −0.0035 (3) 0.30789 (16) 0.0225 (5) H5 0.7752 −0.1515 0.3302 0.027* C6 0.6438 (3) 0.2692 (3) 0.5090 (2) 0.0311 (7) H6 0.5527 0.2186 0.4942 0.037* C7 0.7657 (2) 0.1468 (4) 0.55660 (17) 0.0287 (5) H7 0.7707 −0.0009 0.5793 0.034* C8 0.8795 (3) 0.2827 (4) 0.5647 (2) 0.0286 (6) H8 0.9737 0.2421 0.5933 0.034* C9 0.8268 (2) 0.4899 (3) 0.52219 (17) 0.0275 (5) H9 0.8797 0.6131 0.5178 0.033* C10 0.6820 (2) 0.4814 (4) 0.48745 (18) 0.0304 (5) H10 0.6206 0.5977 0.4552 0.036* C11 0.5000 −0.0124 (4) 0.2500 0.0220 (6) O1 0.5000 −0.2137 (3) 0.2500 0.0372 (7) Fe1 0.75090 (3) 0.25631 (4) 0.40398 (2) 0.0176 (2)

Atomic displacement parameters (Å2₎

U11 _U22 _U33 _U12 _U13 _U23

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C11 0.0247 (15) 0.0167 (14) 0.0216 (15) 0.000 0.0044 (12) 0.000 O1 0.0279 (13) 0.0117 (10) 0.065 (2) 0.000 0.0081 (13) 0.000

Fe1 0.0184 (3) 0.0162 (3) 0.0180 (3) 0.00138 (10) 0.00631 (19) −0.00086 (10)

Geometric parameters (Å, º)

C1—C5 1.424 (3) C6—C10 1.420 (3) C1—C2 1.444 (3) C6—Fe1 2.046 (3) C1—C11 1.477 (2) C6—H6 0.9500 C1—Fe1 2.0344 (19) C7—C8 1.422 (3) C2—C3 1.411 (3) C7—Fe1 2.045 (2) C2—Fe1 2.039 (2) C7—H7 0.9500 C2—H2 0.9500 C8—C9 1.418 (3) C3—C4 1.427 (3) C8—Fe1 2.045 (3) C3—Fe1 2.052 (2) C8—H8 0.9500 C3—H3 0.9500 C9—C10 1.412 (3) C4—C5 1.418 (3) C9—Fe1 2.043 (2) C4—Fe1 2.056 (2) C9—H9 0.9500 C4—H4 0.9500 C10—Fe1 2.038 (2) C5—Fe1 2.0495 (19) C10—H10 0.9500 C5—H5 0.9500 C11—O1 1.237 (3) C6—C7 1.413 (3) C11—C1i _{1.477 (2)}

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C4—C5—Fe1 70.02 (11) C10—Fe1—C7 68.16 (9) C1—C5—Fe1 69.03 (11) C2—Fe1—C7 155.95 (10) C4—C5—H5 125.8 C9—Fe1—C7 68.16 (9) C1—C5—H5 125.8 C8—Fe1—C7 40.70 (10) Fe1—C5—H5 126.7 C6—Fe1—C7 40.42 (10) C7—C6—C10 107.7 (2) C1—Fe1—C5 40.81 (8) C7—C6—Fe1 69.75 (14) C10—Fe1—C5 162.56 (9) C10—C6—Fe1 69.36 (14) C2—Fe1—C5 68.90 (9) C7—C6—H6 126.1 C9—Fe1—C5 156.17 (9) C10—C6—H6 126.1 C8—Fe1—C5 121.80 (9) Fe1—C6—H6 126.3 C6—Fe1—C5 126.20 (9) C6—C7—C8 108.3 (2) C7—Fe1—C5 109.24 (9) C6—C7—Fe1 69.83 (14) C1—Fe1—C3 68.60 (8) C8—C7—Fe1 69.63 (14) C10—Fe1—C3 119.53 (9) C6—C7—H7 125.9 C2—Fe1—C3 40.34 (8) C8—C7—H7 125.9 C9—Fe1—C3 107.04 (9) Fe1—C7—H7 126.3 C8—Fe1—C3 125.21 (10) C9—C8—C7 107.6 (2) C6—Fe1—C3 154.68 (10) C9—C8—Fe1 69.65 (13) C7—Fe1—C3 163.03 (9) C7—C8—Fe1 69.67 (13) C5—Fe1—C3 68.15 (8) C9—C8—H8 126.2 C1—Fe1—C4 68.63 (8) C7—C8—H8 126.2 C10—Fe1—C4 154.94 (9) Fe1—C8—H8 126.0 C2—Fe1—C4 68.59 (9) C10—C9—C8 108.2 (2) C9—Fe1—C4 120.71 (9) C10—C9—Fe1 69.57 (12) C8—Fe1—C4 108.34 (10) C8—C9—Fe1 69.76 (13) C6—Fe1—C4 163.28 (9) C10—C9—H9 125.9 C7—Fe1—C4 126.52 (9) C8—C9—H9 125.9 C5—Fe1—C4 40.43 (8) Fe1—C9—H9 126.3 C3—Fe1—C4 40.66 (9)

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C6—C10—Fe1—C1 76.05 (18) C1—C5—Fe1—C6 73.86 (16) C9—C10—Fe1—C2 −123.20 (13) C4—C5—Fe1—C7 −124.22 (13) C6—C10—Fe1—C2 117.66 (16) C1—C5—Fe1—C7 115.81 (13) C6—C10—Fe1—C9 −119.1 (2) C4—C5—Fe1—C3 37.86 (14) C9—C10—Fe1—C8 37.53 (14) C1—C5—Fe1—C3 −82.12 (13) C6—C10—Fe1—C8 −81.61 (17) C1—C5—Fe1—C4 −119.98 (17) C9—C10—Fe1—C6 119.1 (2) C2—C3—Fe1—C1 38.66 (13) C9—C10—Fe1—C7 81.51 (14) C4—C3—Fe1—C1 −81.70 (14) C6—C10—Fe1—C7 −37.63 (15) C2—C3—Fe1—C10 −79.87 (15) C9—C10—Fe1—C5 166.3 (2) C4—C3—Fe1—C10 159.77 (13) C6—C10—Fe1—C5 47.1 (3) C4—C3—Fe1—C2 −120.36 (19) C9—C10—Fe1—C3 −81.66 (15) C2—C3—Fe1—C9 −122.07 (13) C6—C10—Fe1—C3 159.20 (16) C4—C3—Fe1—C9 117.57 (14) C9—C10—Fe1—C4 −49.5 (3) C2—C3—Fe1—C8 −162.96 (13) C6—C10—Fe1—C4 −168.67 (18) C4—C3—Fe1—C8 76.68 (16) C3—C2—Fe1—C1 −118.65 (18) C2—C3—Fe1—C6 −47.1 (3) C3—C2—Fe1—C10 116.96 (13) C4—C3—Fe1—C6 −167.46 (19) C1—C2—Fe1—C10 −124.39 (13) C2—C3—Fe1—C7 167.1 (3) C3—C2—Fe1—C9 76.32 (15) C4—C3—Fe1—C7 46.7 (4) C1—C2—Fe1—C9 −165.03 (12) C2—C3—Fe1—C5 82.71 (13) C3—C2—Fe1—C8 47.1 (3) C4—C3—Fe1—C5 −37.65 (13) C1—C2—Fe1—C8 165.8 (3) C2—C3—Fe1—C4 120.36 (19) C3—C2—Fe1—C6 158.79 (13) C5—C4—Fe1—C1 −37.44 (12) C1—C2—Fe1—C6 −82.56 (14) C3—C4—Fe1—C1 81.61 (14) C3—C2—Fe1—C7 −170.80 (19) C5—C4—Fe1—C10 −164.31 (19) C1—C2—Fe1—C7 −52.1 (3) C3—C4—Fe1—C10 −45.3 (3) C3—C2—Fe1—C5 −80.67 (13) C5—C4—Fe1—C2 −82.18 (13) C1—C2—Fe1—C5 37.98 (12) C3—C4—Fe1—C2 36.87 (13) C1—C2—Fe1—C3 118.65 (18) C5—C4—Fe1—C9 160.64 (12) C3—C2—Fe1—C4 −37.15 (13) C3—C4—Fe1—C9 −80.31 (15) C1—C2—Fe1—C4 81.50 (13) C5—C4—Fe1—C8 117.84 (13) C10—C9—Fe1—C1 42.4 (3) C3—C4—Fe1—C8 −123.11 (14) C8—C9—Fe1—C1 161.9 (3) C5—C4—Fe1—C6 42.1 (4) C8—C9—Fe1—C10 119.5 (2) C3—C4—Fe1—C6 161.2 (3) C10—C9—Fe1—C2 74.65 (15) C5—C4—Fe1—C7 76.29 (15) C8—C9—Fe1—C2 −165.83 (14) C3—C4—Fe1—C7 −164.66 (13) C10—C9—Fe1—C8 −119.5 (2) C3—C4—Fe1—C5 119.05 (19) C10—C9—Fe1—C6 −37.81 (14) C5—C4—Fe1—C3 −119.05 (19) C8—C9—Fe1—C6 81.72 (17)