(η5-Cyclo­penta­dien­yl)(η6-mesitylamine)ruthenium(II) hexa­fluorido­phosphate

Eva Becker; Karl Kirchner; Kurt Mereiter

doi:10.1107/S1600536809016894

. 2009 May 14;65(Pt 6):m631. doi: 10.1107/S1600536809016894

(η⁵-Cyclopentadienyl)(η⁶-mesitylamine)ruthenium(II) hexafluoridophosphate

Eva Becker ^a, Karl Kirchner ^a, Kurt Mereiter ^b,^*

PMCID: PMC2969571 PMID: 21582999

Abstract

The title compound, [Ru(η⁵-C₅H₅){η⁶-C₆H₂(CH₃)₃NH₂}]PF₆, contains a sandwich complex with a mesitylamine unit which is significantly non-planar at the ipso-carbon of the amino group due to repulsive electronic effects with Ru. The ipso-carbon deviates by 0.107 (3) Å from the least-squares plane of the remaining five benzene ring atoms, which show an r.m.s. deviation of 0.005 Å. N—H⋯F hydrogen-bonding interactions help to consolidate the crystal packing.

Related literature

For general background and a related structure with —N(CH₃)₂ instead of —NH₂, see: Standfest-Hauser et al. (2003 ▶). For related chromium arene complexes, see: Djukic et al. (2000 ▶); Hunter et al. (1992 ▶). For synthetic details, see: Gill & Mann (1982 ▶); Kündig & Monnier (2004 ▶).

Experimental

Crystal data

[Ru(C₅H₅)(C₉H₁₃N)]PF₆
M _r = 446.33
Orthorhombic,
a = 7.5119 (4) Å
b = 10.2047 (6) Å
c = 21.1818 (12) Å
V = 1623.73 (16) Å³
Z = 4
Mo Kα radiation
μ = 1.12 mm⁻¹
T = 173 K
0.55 × 0.30 × 0.26 mm

Data collection

Bruker SMART CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2003 ▶) T _min = 0.62, T _max = 0.75
24305 measured reflections
4741 independent reflections
4650 reflections with I > 2σ(I)
R _int = 0.026

Refinement

R[F ² > 2σ(F ²)] = 0.024
wR(F ²) = 0.055
S = 1.12
4741 reflections
218 parameters
1 restraint
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.65 e Å⁻³
Δρ_min = −0.41 e Å⁻³
Absolute structure: Flack (1983 ▶), 2202 Friedel pairs
Flack parameter: 0.21 (3)

Data collection: SMART (Bruker, 2003 ▶); cell refinement: SAINT (Bruker, 2003 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: SHELXTL (Sheldrick, 2008 ▶); software used to prepare material for publication: SHELXTL.

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809016894/gk2208sup1.cif

e-65-0m631-sup1.cif^{(30.7KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809016894/gk2208Isup2.hkl

e-65-0m631-Isup2.hkl^{(232.3KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Selected bond lengths (Å).

Ru—C1	2.179 (2)
Ru—C2	2.164 (2)
Ru—C3	2.179 (3)
Ru—C4	2.181 (3)
Ru—C5	2.187 (3)
Ru—C6	2.314 (2)
Ru—C7	2.212 (2)
Ru—C8	2.178 (2)
Ru—C9	2.214 (2)
Ru—C10	2.185 (2)
Ru—C11	2.229 (2)

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Table 2. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N—H1A⋯F1	0.87 (2)	2.26 (2)	3.106 (3)	163 (3)
N—H1B⋯F5ⁱ	0.87 (2)	2.43 (3)	3.174 (3)	143 (3)

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Symmetry code: (i) Inline graphic .

Acknowledgments

Financial support by the FWF Austrian Science Fund (project No. P16600-N11) is gratefully acknowledged.

supplementary crystallographic information

Comment

We have shown (Standfest-Hauser et al., 2003) that arene amines hapto-6-coordinated to a cyclopentadienylruthenium fragment (CpRu) are not planar but display a significant shift of the ipso-carbon bearing the amino substituent out of the mean aromatic plane away from the CpRu fragment by about 0.1 to 0.2 Å. This corresponds to a envelope-type folding of the ring by 7–15° for the interplanar angle. The same effect was previously reported for chromium arene complexes (Hunter et al., 1992; Djukic, et al., 2000). Recently, we obtained the title compound, (I), in a crystalline form. This offered the opportunity to study the mentioned effect for a compound with NH₂ instead of N(CH₃)₂. In (I) the cyclopentadienyl ring and the 5-membered ring segment C7—C8—C9—C10—C11 are almost perfectly planar (r.m.s. aplanarities 0.006 and 0.005 Å, respectively) and mutually inclined by 1.0 (1)° (Fig. 1). The ipso-carbon C6 and the amino nitrogen deviate by 0.107 (3) and 0.172 (4) Å, respectively, from ring segment plane and both are bent away from the CpRu fragment. Thus the envelope-type ring folding angle, measured between planes C7—C6—C11 and C7—C8—C9—C10—C11, is 8.3 (3)°. According to FT/B3LYP calculations (Standfest-Hauser et al., 2003) the reason for this envelope deformation of the benzene ring is that the surplus of π-electron density at C6 arising from the π-donor substituent NH₂ becomes less pronounced and a 8° folding was predicted for free [CpRu(η⁶-C₆H₅NH₂)]⁺. These quantities are comparable with the experimental data of [CpRu(η⁶-C₆H₅N(CH₃)₂)]PF₆ (Standfest-Hauser et al., 2003), 0.125 (3) Å (deviation of the ipso-C from the plane of the remaining ring atoms) and 10° (envelope-type ring folding angle), respectively. In this compound and its 2-dimethylamino-pyridine congener, the N-bound methyl groups are bent toward the CpRu moieties due to predicted orbital repulsion effects between dimethylamino nitrogen and ipso-carbon. This differs from (I), where the hydrogen atoms are bent off from the CpRu moiety and the nitrogen behaves more pyramidal. We attribute this deviation to the formation of two N—H···F hydrogen bonds (Fig. 1 and Table 2), absent in the dimethylamino compounds. As shown in Fig. 2, these bonds form zigzag chains along the b axis of (I). Further structural coherence is provided by π-π-stacking between Ru complexes, which form columns along the a axis with short stacking distances such as C4—C6(1 + x,y,z) = 3.482 (4) Å and C3—C7(1 + x,y,z) = 3.572 (4) Å. Weak C—H···F interactions donated by methyl, Cp and arene H-atoms stiffen the structure too, e.g. C3···F6(1 - x,-1/2 + y,1/2 - z) = 3.280 (4) Å.

Experimental

To a solution of [CpRu(CH₃CN)₃]PF₆ (Gill, & Mann, 1982; Kündig & Monnier, 2004; 120 mg, 0.276 mmol) in CH₂Cl₂ (5 ml) mesitylamine (41 µL, 0.290 mmol) was added. After the mixture was stirred at room temperature for 1 h, the solvent was removed under vacuum and the resulting white solid of (I) was collected on a glass frit and washed twice with diethyl ether (10 ml). Yield: 118 mg (96%). ¹H NMR (δ, acetone-d₆, 20°C): 6.02 (s, 2H, Mes^3,5), 5.13 (bs, 2H, NH₂), 5.09 (s, 5H, Cp), 2.31 (s, 6H, Me^2,6), 2.17 (s, 3H, Me⁴). ¹³C{¹H} NMR (δ, acetone-d₆, 20°C): 123.3 (1 C, Mes¹), 94.9 (1 C, Mes⁴), 87.0 (2 C, Mes^2,6), 83.7 (2 C, Mes^3,5), 79.9 (5 C, Cp), 18.5 (1 C, Me⁴), 16.8 (2 C, Me^2,6). Colourless crystals of (I) were grown from CH₂Cl₂ using vapour diffusion of diethyl ether at room temperature.