Crystal structure of ruthenocenecarbo-nitrile.

The mol-ecular structure of ruthenocenecarbo-nitrile, [Ru(η(5)-C5H4C N)(η(5)-C5H5)], exhibits point group symmetry m, with the mirror plane bis-ecting the mol-ecule through the C N substituent. The Ru(II) atom is slightly shifted from the η(5)-C5H4 centroid towards the C N substituent. In the crystal, mol-ecules are arranged in columns parallel to [100]. One-dimensional inter-molecular π-π inter-actions [3.363 (3) Å] between the C N carbon atom and one carbon of the cyclo-penta-dienyl ring of the overlaying mol-ecule are present.

Chemical context

The nitrile group is isoelectronic with the acetylid function (Bonniard et al., 2011 ▸), which has already been investigated in electron-transfer studies (see, for example, Lang et al., 2006 ▸; Poppitz et al., 2014 ▸; Speck et al., 2012 ▸; Hildebrandt & Lang, 2013 ▸; Miesel et al., 2013 ▸). Coordination of, for example, ferrocenecarbo­nitrile towards transition metals M will allow investigation of the electronic properties of —C N—M— or —C N—M—N C— bridging units. A synthesis for ferrocenecarbo­nitrile has already been described in 1957 (Graham et al., 1957 ▸); however, only one example of an application in electrochemical studies has been described by Dowling et al. (1981 ▸). This prompted us to synthesize ferrocenecarbo­nitrile transition metal complexes to investigate the electronic properties of the —C N—M—N C— bridging units (Strehler et al. 2013 ▸, 2014 ▸). In a continuation of this work, we present herein the synthesis and crystal structure of the related ruthenocenecarbo­nitrile, (I). The synthesis of this compound was realized by treatment of formyl­ruthenocene with hydroxyl­amine hydro­chloride, zinc oxide and potassium iodide in aceto­nitrile, which is similar to a procedure already described for the synthesis of ferrocenecarbo­nitrile (Kivrak & Zora, 2007 ▸).

Structural commentary

The title compound contains one half-mol­ecule in the asymmetric unit with a mirror plane bis­ecting the mol­ecule through atoms C1, C2, C5, N1 and Ru1 (Fig. 1 ▸). The Ru1–centroid distance to the C N-substituted cyclo­penta­dienyl ring is slightly increased [1.8179 (1) Å] compared to the unsubstituted C5H5 unit [1.8157 (1) Å]. Both cyclo­penta­dienyl rings adopt an ideally eclipsed conformation and are virtually oriented parallel towards each other, which is expressed by the bond angle at the RuII between the two centroids (= D), with D(C5H4)—Ru1—D(C5H5) = 178.87 (1)°. However, the RuII atom is slightly shifted from the centre of the C5 ring to the nitrile-bonded C2 atom, which can be explained best by the significantly different Ru—C bond lengths (Table 1 ▸) and also the Ru—D—C angles, which should ideally be 90° (Table 1 ▸). This is in accordance with the shift in the ferrocenedicarbo­nitrile structure (Altmannshofer et al., 2008 ▸). The C N substituent itself is bent away from the metal atom in (I), with a maximum shift for N1 [0.047 (4) Å].

Figure 1

The mol­ecular structure of (I), with displacement ellipsoids drawn at the 50% probability level. All H atoms have been omitted for clarity. [Symmetry code: (A) x, −y + , z.]

Table 1

Selected bond lengths () and angles () for the clarification of the shift of the Ru1 atom towards the CN substituent in (I)

D is the centroid of the C5H4 or C5H5 ring.

	C2	C3	C4	C5	C6	C7
Ru1C	2.1650(18)	2.1886(13)	2.2013(12)	2.1779(18)	2.1847(13)	2.1879(12)
CDRu1	88.90(8)	89.63(6)	90.93(6)	89.75(9)	89.95(6)	90.16(6)

Supra­molecular features

The packing of (I) consists of a layer-type structure parallel to (010) with the direction of the C N function aligned parallel to [10], alternating between adjacent layers. A further order is observed by a columnar arrangement of slightly tilted mol­ecules parallel to [100]. Weak inter­molecular π–π inter­actions within the sum of the van der Waals radii (Σ = 3.4 Å; Bondi, 1964 ▸) are present between C5 and the C1′ atom [3.363 (3) Å] of the overlying mol­ecule in the same layer (Fig. 2 ▸).

Figure 2

Inter­molecular π–π inter­actions (blue) between C5 and C1′ in the crystal structure of (I). All H atoms have been omitted for clarity. [Symmetry code: (′) x − 1, y, z.]

Database survey

The ruthenocene backbone is hardly described in the literature. Reported derivatives contain sp (ethyn­yl) (Sato et al., 1997 ▸; Packheiser et al., 2008 ▸; Jakob et al., 2008 ▸, 2009a ▸), sp 2 (Sato et al., 1998 ▸, 2004 ▸; Jakob et al., 2009b ▸) and sp 3 (Sokolov et al., 2010 ▸; Barlow et al., 2001 ▸) carbon substituents or a carb­oxy­lic acid moiety (Zhang & Coppens, 2001 ▸) and its respective RuII complex (Wyman et al., 2005 ▸). They all exhibit similar Ru—D distances (1.795–1.823 Å) as compared to (I) [1.8179 (1)–1.8157 (1) Å] or unsubstituted ruthenocene (1.794–1.816 Å) (Ma & Coppens, 2003 ▸; Borissova et al., 2008 ▸; Seiler & Dunitz, 1980 ▸).

Comparison of the C—C [1.431 (3) Å] and the C N distances [1.148 (3) Å] with the respective ferrocene carbo­nitrile derivatives (C N = 1.133–1.150; C—C = 1.428–1.433 Å; Altmannshofer et al., 2008 ▸; Dayaker et al., 2010 ▸; Bell et al., 1996 ▸; Nemykin et al., 2007 ▸; Erben et al., 2007 ▸) reveals no significant influence of the central metal atom on the electronic properties of the substituent.

Synthesis and crystallization

Formyl­ruthenocene was prepared according to a published procedure (Mueller-Westerhoff et al., 1993 ▸). Synthesis of ruthenocenecarbo­nitrile, (I): formyl­ruthenocene (2.27 g, 8.8 mmol), hydroxyl­amine hydro­chloride (0.96 g, 13.8 mmol), zinc oxide (0.86 g, 10.6 mmol) and potassium iodide (1.76 g, 10.6 mmol) were suspended in 120 ml of dry aceto­nitrile. The mixture was stirred for 4 h at precisely 368 K. After cooling the reaction mixture to ambient temperature, 18 ml of an aqueous Na2S2O3 (5%) solution were added in a single portion, and stirring was continued for additional 20 min. Solid particles were removed by filtration and the filtrate was extracted with ethyl acetate (3 × 50 ml). The combined organic layers were dried over MgSO4. All volatiles were removed under reduced pressure and the crude product was purified by flash chromatography on aluminum oxide using di­chloro­methane as eluent. Greenish crystals of (I) were obtained by slow evaporation of a saturated di­chloro­methane solution containing (I) at ambient temperature (yield: 820 mg, 3.3 mmol, 38% based on formyl­ruthenocene). IR (KBr, cm−1): ν = 2226 (m, C N), 2854 (s), 2925 (s), 3082 (m, C—H). 1H NMR (500.3 MHz, CDCl3, 298 K): δ 4.69 (s, 5H, C5H5), 4.70 (pt, 2H, J H,H = 1.8 Hz), 4.70 (pt, 2H, J H,H = 1.8 Hz). 13C{1H} NMR (125.7 MHz, CDCl3, 298 K): δ = 55.3 (Ci-C5H4), 72.4 (C5H4), 72.9 (C5H5), 73.5 (C5H4), 119.4 (CN). HRMS (ESI–TOF, M +): C11H9NRu: m/z = 256.9792 (calc. 256.9776).

Refinement

C-bonded H atoms were placed in calculated positions and constrained to ride on their parent atoms, with U(H) = 1.2U eq(C) and a C—H distance of 0.93 Å. Crystal data, data collection and structure refinement details are summarized in Table 2 ▸.

Table 2

Experimental details

Crystal data
Chemical formula	[Ru(C5H5)(C6H4N)]
M r	256.26
Crystal system, space group	Monoclinic, P21/m
Temperature (K)	110
a, b, c ()	7.2023(2), 8.6802(2), 7.2922(1)
()	106.497(2)
V (3)	437.12(2)
Z	2
Radiation type	Mo K
(mm1)	1.74
Crystal size (mm)	0.38 0.30 0.30
Data collection
Diffractometer	Oxford Gemini S CCD
Absorption correction	Multi-scan (CrysAlis RED; Oxford Diffraction, 2006 ▸)
T min, T max	0.849, 1.000
No. of measured, independent and observed [I > 2(I)] reflections	27710, 900, 877
R int	0.019
(sin /)max (1)	0.617
Refinement
R[F 2 > 2(F 2)], wR(F 2), S	0.012, 0.032, 1.05
No. of reflections	900
No. of parameters	67
H-atom treatment	H-atom parameters constrained
max, min (e 3)	0.27, 0.39

Computer programs: CrysAlis CCD and CrysAlis RED (Oxford Diffraction, 2006 ▸), SHELXS97 and SHELXTL (Sheldrick, 2008 ▸), SHELXL2013 (Sheldrick, 2015 ▸), ORTEP-3 for Windows and WinGX (Farrugia, 2012 ▸) and publCIF (Westrip, 2010 ▸).

Crystal structure: contains datablock(s) I. DOI: 10.1107/S205698901500540X/wm5119sup1.cif

Structure factors: contains datablock(s) I. DOI: 10.1107/S205698901500540X/wm5119Isup2.hkl

CCDC reference: 1054219

Additional supporting information: crystallographic information; 3D view; checkCIF report

[Ru(C5H5)(C6H4N)]	F(000) = 252
Mr = 256.26	Dx = 1.947 Mg m−3
Monoclinic, P21/m	Mo Kα radiation, λ = 0.71073 Å
a = 7.2023 (2) Å	Cell parameters from 26762 reflections
b = 8.6802 (2) Å	θ = 3.5–28.7°
c = 7.2922 (1) Å	µ = 1.74 mm−1
β = 106.497 (2)°	T = 110 K
V = 437.12 (2) Å3	Block, yellow green
Z = 2	0.38 × 0.30 × 0.30 mm

Oxford Gemini S CCD diffractometer	900 independent reflections
Radiation source: fine-focus sealed tube	877 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.019
ω scans	θmax = 26.0°, θmin = 3.5°
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006)	h = −8→8
Tmin = 0.849, Tmax = 1.000	k = −10→10
27710 measured reflections	l = −8→8

Refinement on F2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.012	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.032	H-atom parameters constrained
S = 1.05	w = 1/[σ2(Fo2) + (0.0218P)2 + 0.1909P] where P = (Fo2 + 2Fc2)/3
900 reflections	(Δ/σ)max < 0.001
67 parameters	Δρmax = 0.27 e Å−3
0 restraints	Δρmin = −0.39 e Å−3

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.

	x	y	z	Uiso*/Ueq
C1	−0.4152 (3)	0.2500	−0.0364 (3)	0.0162 (4)
C2	−0.3084 (3)	0.2500	0.1617 (3)	0.0142 (4)
C3	−0.24721 (18)	0.11497 (16)	0.27791 (19)	0.0142 (3)
H3C	−0.2679	0.0130	0.2382	0.017*
C4	−0.14854 (18)	0.16776 (15)	0.46603 (18)	0.0145 (3)
H4C	−0.0935	0.1053	0.5710	0.017*
C5	0.1429 (3)	0.2500	0.0334 (3)	0.0185 (4)
H5C	0.0744	0.2500	−0.0957	0.022*
C6	0.20428 (19)	0.11674 (17)	0.1491 (2)	0.0175 (3)
H6C	0.1832	0.0149	0.1089	0.021*
C7	0.30392 (17)	0.16746 (16)	0.33757 (19)	0.0158 (3)
H7C	0.3591	0.1045	0.4420	0.019*
N1	−0.5024 (2)	0.2500	−0.1949 (3)	0.0244 (4)
Ru1	0.00474 (2)	0.2500	0.26311 (2)	0.00953 (7)

	U11	U22	U33	U12	U13	U23
C1	0.0120 (8)	0.0168 (9)	0.0198 (10)	0.000	0.0045 (7)	0.000
C2	0.0093 (8)	0.0168 (9)	0.0170 (9)	0.000	0.0044 (7)	0.000
C3	0.0111 (6)	0.0148 (7)	0.0182 (6)	−0.0022 (5)	0.0065 (5)	−0.0003 (5)
C4	0.0145 (6)	0.0163 (7)	0.0146 (6)	0.0003 (5)	0.0072 (5)	0.0029 (5)
C5	0.0155 (9)	0.0283 (11)	0.0145 (9)	0.000	0.0087 (7)	0.000
C6	0.0143 (6)	0.0190 (7)	0.0222 (7)	0.0005 (5)	0.0101 (5)	−0.0047 (6)
C7	0.0098 (6)	0.0191 (7)	0.0193 (6)	0.0033 (5)	0.0054 (5)	0.0029 (5)
N1	0.0222 (9)	0.0274 (10)	0.0208 (9)	0.000	0.0015 (7)	0.000
Ru1	0.00850 (10)	0.00992 (10)	0.01040 (10)	0.000	0.00305 (6)	0.000

C1—N1	1.148 (3)	C5—Ru1	2.1780 (18)
C1—C2	1.431 (3)	C5—H5C	0.9300
C2—C3i	1.4401 (17)	C6—C7	1.4274 (19)
C2—C3	1.4401 (17)	C6—Ru1	2.1848 (13)
C2—Ru1	2.1649 (18)	C6—H6C	0.9300
C3—C4	1.4294 (18)	C7—C7i	1.433 (3)
C3—Ru1	2.1885 (13)	C7—Ru1	2.1878 (12)
C3—H3C	0.9300	C7—H7C	0.9300
C4—C4i	1.428 (3)	Ru1—C6i	2.1848 (13)
C4—Ru1	2.2013 (12)	Ru1—C7i	2.1878 (12)
C4—H4C	0.9300	Ru1—C3i	2.1885 (13)
C5—C6i	1.4262 (18)	Ru1—C4i	2.2013 (12)
C5—C6	1.4262 (18)
N1—C1—C2	179.4 (2)	C5—Ru1—C6	38.16 (5)
C1—C2—C3i	125.52 (8)	C6i—Ru1—C6	63.94 (8)
C1—C2—C3	125.52 (8)	C2—Ru1—C7i	160.38 (4)
C3i—C2—C3	108.96 (16)	C5—Ru1—C7i	63.77 (6)
C1—C2—Ru1	123.64 (13)	C6i—Ru1—C7i	38.11 (5)
C3i—C2—Ru1	71.57 (8)	C6—Ru1—C7i	63.89 (5)
C3—C2—Ru1	71.57 (8)	C2—Ru1—C7	160.38 (4)
C4—C3—C2	106.82 (12)	C5—Ru1—C7	63.77 (6)
C4—C3—Ru1	71.48 (7)	C6i—Ru1—C7	63.89 (5)
C2—C3—Ru1	69.80 (9)	C6—Ru1—C7	38.11 (5)
C4—C3—H3C	126.6	C7i—Ru1—C7	38.23 (7)
C2—C3—H3C	126.6	C2—Ru1—C3i	38.63 (4)
Ru1—C3—H3C	123.8	C5—Ru1—C3i	127.17 (5)
C4i—C4—C3	108.70 (8)	C6i—Ru1—C3i	112.30 (6)
C4i—C4—Ru1	71.08 (3)	C6—Ru1—C3i	161.19 (5)
C3—C4—Ru1	70.51 (7)	C7i—Ru1—C3i	125.76 (5)
C4i—C4—H4C	125.7	C7—Ru1—C3i	159.25 (5)
C3—C4—H4C	125.7	C2—Ru1—C3	38.63 (4)
Ru1—C4—H4C	124.4	C5—Ru1—C3	127.17 (5)
C6i—C5—C6	108.40 (17)	C6i—Ru1—C3	161.18 (5)
C6i—C5—Ru1	71.18 (9)	C6—Ru1—C3	112.30 (6)
C6—C5—Ru1	71.18 (9)	C7i—Ru1—C3	159.25 (5)
C6i—C5—H5C	125.8	C7—Ru1—C3	125.76 (5)
C6—C5—H5C	125.8	C3i—Ru1—C3	64.76 (7)
Ru1—C5—H5C	123.5	C2—Ru1—C4i	63.69 (6)
C5—C6—C7	107.83 (13)	C5—Ru1—C4i	160.55 (4)
C5—C6—Ru1	70.66 (9)	C6i—Ru1—C4i	126.43 (5)
C7—C6—Ru1	71.06 (7)	C6—Ru1—C4i	159.58 (5)
C5—C6—H6C	126.1	C7i—Ru1—C4i	111.94 (5)
C7—C6—H6C	126.1	C7—Ru1—C4i	125.87 (5)
Ru1—C6—H6C	123.8	C3i—Ru1—C4i	38.01 (5)
C6—C7—C7i	107.97 (8)	C3—Ru1—C4i	63.86 (5)
C6—C7—Ru1	70.83 (7)	C2—Ru1—C4	63.69 (6)
C7i—C7—Ru1	70.88 (4)	C5—Ru1—C4	160.55 (4)
C6—C7—H7C	126.0	C6i—Ru1—C4	159.58 (5)
C7i—C7—H7C	126.0	C6—Ru1—C4	126.42 (5)
Ru1—C7—H7C	123.9	C7i—Ru1—C4	125.87 (5)
C2—Ru1—C5	113.36 (7)	C7—Ru1—C4	111.94 (5)
C2—Ru1—C6i	127.17 (5)	C3i—Ru1—C4	63.86 (5)
C5—Ru1—C6i	38.16 (5)	C3—Ru1—C4	38.01 (5)
C2—Ru1—C6	127.17 (5)	C4i—Ru1—C4	37.84 (7)
C1—C2—C3—C4	−179.04 (16)	C2—C3—C4—Ru1	−61.20 (10)
C3i—C2—C3—C4	0.13 (19)	C6i—C5—C6—C7	0.1 (2)
Ru1—C2—C3—C4	62.30 (9)	Ru1—C5—C6—C7	−61.69 (9)
C1—C2—C3—Ru1	118.66 (18)	C6i—C5—C6—Ru1	61.79 (12)
C3i—C2—C3—Ru1	−62.17 (12)	C5—C6—C7—C7i	−0.06 (12)
C2—C3—C4—C4i	−0.08 (12)	Ru1—C6—C7—C7i	−61.50 (4)
Ru1—C3—C4—C4i	61.12 (4)	C5—C6—C7—Ru1	61.44 (10)