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Journal logoCRYSTALLOGRAPHIC
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ISSN: 2056-9890
Volume 71| Part 4| April 2015| Pages 371-373

Serendipitous preparation of fac-(aceto­nitrile-κN)tri­chlorido­[(1,2,5,6-η)-cyclo­octa-1,5-diene]iridium(III)

aDepartment of Chemistry, Virginia Tech, Blacksburg, VA 24061, USA
*Correspondence e-mail: jmerola@vt.edu

Edited by S. Parkin, University of Kentucky, USA (Received 21 February 2015; accepted 10 March 2015; online 14 March 2015)

A reaction between [(COD)IrCl]2 (COD is cyclo­octa-1,5-diene), HCl and indene failed to provide the hoped for chlorido­indenyliridium dimer, but instead produced the title compound, [IrCl3(CH3CN)(C8H12)], which is an octa­hedral complex of iridium(III) with a chelating cyclo­octa-1,5-diene ligand, three chloride ligands in a fac arrangement, and one aceto­nitrile ligand. Attempts to devise a rational synthesis for the title compound were unsuccessful.

1. Chemical context

We have published recently on the synthesis of a series of tetra­methyl­alkyl­cyclo­penta­dienyliridium complexes by the direct reaction between tetra­methyl­alkyl­cyclo­penta­diene and iridium chloride, giving the [Cp*RIrCl2]2 dimer (Morris et al., 2014[Morris, D. M., McGeagh, M., De Peña, D. & Merola, J. S. (2014). Polyhedron, 84, 120-135.]). From the dimer, a variety of other compounds can be made, such as amino acid complexes, that have shown significant anti-mycobacterial activity (Karpin et al., 2013[Karpin, G., Merola, J. S. & Falkinham, J. O. (2013). Antimicrob. Agents Chemother. 57, 3434-3436.]). Some of the reactions produced low yields of the chlorido-bridged dimer, thus limiting the number of products that could be made and tested.

[Scheme 1]

An alternate route to Cp*-type chlorido iridium dimers was reported using [(COD)IrCl]2 as the starting material (El Amouri et al., 1994[El Amouri, H., Gruselle, M. & Jaouén, G. (1994). Synth. React. Inorg. Met.-Org. Chem. 24, 395-400.]) and, in our hands, this route does have promise for providing higher yields for many of the compounds. However, in the case of indene, there was no indication that an indenyl iridium complex had been prepared. Instead, a yellow–brown intra­ctable solid was formed. Several attempts to dissolve the solid and to separate products through fractional crystallization all failed. During the course of this work-up, one of the solvents used was aceto­nitrile. At some point, the product mixture was allowed to stand in solution, and after about 24 hours several very nicely shaped rectangular prisms had formed in the sample. These crystals were examined by X-ray crystallography and the results of that structure determination are reported here.

2. Structural commentary

While the total number of cyclo­octa-1,5-diene complexes structurally characterized is quite large, the number that are directly comparable to the title compound is small. The title compound is a pseudo-octa­hedral complex of iridium with three chloride ligands occupying one face of the octa­hedron and the alkenes of the COD and the aceto­nitrile ligand occupying the opposite face (Fig. 1[link]). Considering the varying ligands about the central iridium, there is very little distortion from ideal octa­hedral angles, with the most significant distortion being the N1—Ir1—Cl2 distorted away from the COD group with an angle of 164.05 (11)°. All other angles, including those involving the alkene centroids, deviate by no more than 5° from the ideal. All three Ir—Cl bond lengths are similar [range 2.3603 (11) to 2.3670 (11) Å], which is in keeping with both types of trans ligands, alkene and aceto­nitrile, being expected to be strong trans-influence ligands and would have a similar magnitude of effect on the chloride trans to either ligand.

[Figure 1]
Figure 1
The asymmetric unit of the title compound. Displacement ellipsoids are shown at the 50% probability level.

The facial Ir—Cl distances may be contrasted with the average distance of 2.441 (2) Å for fac-[(Me3P)3IrCl3] (CCDC: 896073) and related compounds (Merola et al., 2013[Merola, J. S., Franks, M. A. & Frazier, J. F. (2013). Polyhedron, 54, 67-73.]) that have somewhat longer Ir—Cl distances due to the effect of the trans PMe3 groups.

Choudhury et al. (2005[Choudhury, J., Podder, S. & Roy, S. (2005). J. Am. Chem. Soc. 127, 6162-6163.]) reported on a COD complex of iridium with three chlorides and a SnCl3 ligand completing the octa­hedral coordination about the central Ir atom (CCDC: 273475). In that case, though, the compound is a dinuclear one with Ir—Cl—Ir bridges. So, there are long Ir—Cl bonds (those involved in bridging) of 2.544 (4) Å and a shorter terminal Ir—Cl bond of 2.385 (6) Å. C=C bond lengths for the COD ring are similar to the title compound at 1.38 (1) and 1.41 (2) Å.

3. Supra­molecular features

Although there appear to be some close C—H⋯Cl inter­molecular inter­actions, there are no important supra­molecular features to speak of in this structure.

4. Database survey

A substructure search of the CCDC (Groom & Allen, 2014[Groom, C. R. & Allen, F. H. (2014). Angew. Chem. Int. Ed. 53, 662-671.]) for the 1,5-COD-Ir fragment resulted in over 850 hits. This is not a surprising result since [CODIrCl]2 is a convenient, high-yield organometallic starting material made in one step from IrCl3·H2O and cyclo­octa-1,5-diene (Crabtree & Morris, 1977[Crabtree, R. H. & Morris, G. E. (1977). J. Organomet. Chem. 135, 395-403.]). From [CODIrCl]2, a wide variety of ligand addition, chloride replacement or bridge-splitting reactions can be carried out, leading to a wide variety of compounds containing the COD chelate. Using Mercury (Macrae et al., 2008[Macrae, C. F., Bruno, I. J., Chisholm, J. A., Edgington, P. R., McCabe, P., Pidcock, E., Rodriguez-Monge, L., Taylor, R., van de Streek, J. & Wood, P. A. (2008). J. Appl. Cryst. 41, 466-470.]), an analysis of the COD–Ir search of the database for structures with an octahedral coordination around the metal showed that the C=C bonds of the COD ligands ranged from 1.184 to 1.508 Å with a mean of 1.394 Å. For the title compound, the values of 1.392 (7) and 1.389 (6) Å are pretty much right at the mean for COD C=C bonds.

An analysis of the CCDC database (Groom & Allen, 2014[Groom, C. R. & Allen, F. H. (2014). Angew. Chem. Int. Ed. 53, 662-671.]) for octa­hedral iridium complexes with aceto­nitrile ligands uncovered 99 hits with Ir—N distances measuring from a minimum of 1.897 Å to a maximum of 2.246 Å with a mean of 2.068 Å. For the title compound, the Ir—N distance of 2.023 (4) Å places it just below the mean.

5. Synthesis and crystallization

The title complex was formed as a few isolated crystals from an attempted reaction between [(COD)IrCl]2 and indene with HCl in an attempt to synthesize the [indenylIrCl2]2 dimer, which would have been a useful starting material for our studies. Unfortunately, this did not provide the desired product. The reaction produced some very intra­ctable solids. After multiple attempts to dissolve the solid in many different solvents, including aceto­nitrile, some well-shaped prisms formed on the side of the flask and these crystals were used in this investigation and were shown to be that of the title complex. Attempts to make this material in a rational fashion were not successful.

6. Refinement

Crystal data, data collection and structure refinement details are summarized in Table 1[link]. H atoms were positioned geometrically and refined as riding with C—H = 0.96–0.98 Å, and with Uiso(H) = 1.2Ueq(C) or 1.5Ueq(Cmeth­yl).

Table 1
Experimental details

Crystal data
Chemical formula [IrCl3(C2H3N)(C8H12)]
Mr 447.78
Crystal system, space group Orthorhombic, P212121
Temperature (K) 100
a, b, c (Å) 8.25131 (10), 11.85605 (14), 12.94150 (15)
V3) 1266.04 (3)
Z 4
Radiation type Mo Kα
μ (mm−1) 11.15
Crystal size (mm) 0.22 × 0.15 × 0.11
 
Data collection
Diffractometer Agilent Xcalibur Eos Gemini ultra
Absorption correction Analytical (SCALE3 ABSPACK; Clark & Reid, 1995[Clark, R. C. & Reid, J. S. (1995). Acta Cryst. A51, 887-897.])
Tmin, Tmax 0.204, 0.396
No. of measured, independent and observed [I > 2σ(I)] reflections 27207, 4333, 4173
Rint 0.040
(sin θ/λ)max−1) 0.755
 
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.019, 0.038, 1.08
No. of reflections 4333
No. of parameters 137
H-atom treatment H-atom parameters constrained
Δρmax, Δρmin (e Å−3) 1.07, −0.74
Absolute structure Flack x determined using 1715 quotients [(I+)−(I)]/[(I+)+(I)] (Parsons et al., 2013[Parsons, S., Flack, H. D. & Wagner, T. (2013). Acta Cryst. B69, 249-259.])
Absolute structure parameter −0.011 (4)
Computer programs: CrysAlis PRO (Agilent, 2014[Agilent (2014). CrysAlis PRO. Agilent Technologies, Yarnton, England.]), SHELXS97 and SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]) and OLEX2 (Dolomanov et al., 2009[Dolomanov, O. V., Bourhis, L. J., Gildea, R. J., Howard, J. A. K. & Puschmann, H. (2009). J. Appl. Cryst. 42, 339-341.]).

Supporting information


Computing details top

Data collection: CrysAlis PRO (Agilent, 2014); cell refinement: CrysAlis PRO (Agilent, 2014); data reduction: CrysAlis PRO (Agilent, 2014); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: OLEX2 (Dolomanov et al., 2009); software used to prepare material for publication: OLEX2 (Dolomanov et al., 2009).

fac-(Acetonitrile-κN)trichlorido[(1,2,5,6-η)-cycloocta-1,5-diene]iridium(III) top
Crystal data top
[IrCl3(C2H3N)(C8H12)]Dx = 2.349 Mg m3
Mr = 447.78Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, P212121Cell parameters from 12030 reflections
a = 8.25131 (10) Åθ = 4.0–32.2°
b = 11.85605 (14) ŵ = 11.15 mm1
c = 12.94150 (15) ÅT = 100 K
V = 1266.04 (3) Å3Prism, clear light orange
Z = 40.22 × 0.15 × 0.11 mm
F(000) = 840
Data collection top
Agilent Xcalibur Eos Gemini ultra
diffractometer
4333 independent reflections
Radiation source: Enhance (Mo) X-ray Source, Agilent Gemini System4173 reflections with I > 2σ(I)
Graphite monochromatorRint = 0.040
Detector resolution: 16.0122 pixels mm-1θmax = 32.4°, θmin = 3.4°
ω scansh = 1112
Absorption correction: analytical
(SCALE3 ABSPACK; Clark & Reid, 1995)
k = 1717
Tmin = 0.204, Tmax = 0.396l = 1919
27207 measured reflections
Refinement top
Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.019 w = 1/[σ2(Fo2) + (0.0124P)2 + 1.2315P]
where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.038(Δ/σ)max = 0.002
S = 1.08Δρmax = 1.07 e Å3
4333 reflectionsΔρmin = 0.74 e Å3
137 parametersAbsolute structure: Flack x determined using 1715 quotients [(I+)-(I-)]/[(I+)+(I-)] (Parsons et al., 2013)
0 restraintsAbsolute structure parameter: 0.011 (4)
Primary atom site location: structure-invariant direct methods
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Ir10.70199 (2)0.47821 (2)0.68347 (2)0.01178 (4)
Cl10.68059 (17)0.64680 (9)0.78048 (9)0.0238 (2)
Cl20.85370 (14)0.58778 (9)0.56587 (9)0.0202 (2)
Cl30.47576 (13)0.52459 (13)0.57940 (9)0.0275 (2)
N10.5308 (5)0.4220 (3)0.7828 (3)0.0153 (7)
C10.7775 (6)0.3484 (4)0.5677 (3)0.0210 (9)
H10.72270.35400.50080.025*
C20.6888 (7)0.2940 (4)0.6442 (3)0.0210 (9)
H20.58130.26860.62190.025*
C30.7669 (7)0.2197 (4)0.7247 (4)0.0268 (12)
H3A0.86390.18630.69530.032*
H3B0.69300.15870.74130.032*
C40.8132 (6)0.2806 (4)0.8253 (4)0.0245 (9)
H4A0.72410.27360.87370.029*
H4B0.90630.24300.85530.029*
C50.8528 (5)0.4040 (4)0.8121 (4)0.0202 (9)
H50.85180.44770.87640.024*
C60.9554 (6)0.4463 (4)0.7360 (4)0.0229 (10)
H61.01320.51480.75680.028*
C71.0494 (6)0.3734 (5)0.6606 (4)0.0289 (12)
H7A1.08160.30480.69590.035*
H7B1.14760.41320.64140.035*
C80.9592 (6)0.3407 (4)0.5616 (4)0.0254 (11)
H8A0.99630.38920.50610.030*
H8B0.98850.26400.54370.030*
C90.4307 (5)0.3980 (4)0.8376 (3)0.0174 (9)
C100.3017 (7)0.3700 (4)0.9097 (3)0.0246 (9)
H10A0.20250.40470.88740.037*
H10B0.32940.39720.97730.037*
H10C0.28790.28960.91200.037*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Ir10.01257 (6)0.01427 (6)0.00849 (6)0.00042 (6)0.00024 (6)0.00067 (6)
Cl10.0356 (7)0.0166 (5)0.0193 (5)0.0010 (5)0.0073 (5)0.0029 (4)
Cl20.0229 (5)0.0206 (5)0.0170 (5)0.0021 (4)0.0046 (4)0.0034 (4)
Cl30.0177 (5)0.0456 (7)0.0191 (5)0.0062 (5)0.0037 (4)0.0099 (6)
N10.0216 (19)0.0134 (17)0.0110 (16)0.0012 (14)0.0036 (14)0.0013 (13)
C10.027 (3)0.022 (2)0.014 (2)0.002 (2)0.0019 (19)0.0038 (16)
C20.031 (2)0.0162 (19)0.0162 (19)0.006 (2)0.002 (2)0.0054 (15)
C30.041 (3)0.016 (2)0.024 (2)0.007 (2)0.012 (2)0.0051 (18)
C40.026 (2)0.027 (2)0.020 (2)0.0060 (19)0.001 (2)0.0097 (19)
C50.0196 (19)0.028 (2)0.0133 (19)0.0018 (16)0.0060 (19)0.006 (2)
C60.015 (2)0.036 (3)0.018 (2)0.0004 (18)0.0079 (17)0.0053 (19)
C70.016 (2)0.040 (3)0.030 (3)0.010 (2)0.0045 (19)0.009 (2)
C80.030 (3)0.024 (2)0.022 (2)0.008 (2)0.011 (2)0.002 (2)
C90.0157 (19)0.021 (2)0.015 (2)0.0023 (16)0.0014 (15)0.0035 (16)
C100.020 (2)0.037 (3)0.017 (2)0.007 (2)0.003 (2)0.0031 (18)
Geometric parameters (Å, º) top
Ir1—Cl12.3670 (11)C4—H4A0.9700
Ir1—Cl22.3603 (11)C4—H4B0.9700
Ir1—Cl32.3666 (10)C4—C51.509 (6)
Ir1—N12.023 (4)C5—H50.9800
Ir1—C12.236 (4)C5—C61.392 (7)
Ir1—C22.245 (4)C6—H60.9800
Ir1—C52.257 (5)C6—C71.517 (7)
Ir1—C62.231 (4)C7—H7A0.9700
N1—C91.125 (6)C7—H7B0.9700
C1—H10.9800C7—C81.531 (8)
C1—C21.389 (6)C8—H8A0.9700
C1—C81.504 (7)C8—H8B0.9700
C2—H20.9800C9—C101.454 (6)
C2—C31.510 (7)C10—H10A0.9600
C3—H3A0.9700C10—H10B0.9600
C3—H3B0.9700C10—H10C0.9600
C3—C41.537 (7)
Cl2—Ir1—Cl185.23 (4)C2—C3—H3B108.6
Cl2—Ir1—Cl385.61 (4)C2—C3—C4114.6 (4)
Cl3—Ir1—Cl192.68 (5)H3A—C3—H3B107.6
N1—Ir1—Cl183.63 (11)C4—C3—H3A108.6
N1—Ir1—Cl2164.05 (11)C4—C3—H3B108.6
N1—Ir1—Cl383.55 (11)C3—C4—H4A108.6
N1—Ir1—C1113.18 (16)C3—C4—H4B108.6
N1—Ir1—C277.86 (16)H4A—C4—H4B107.6
N1—Ir1—C577.73 (16)C5—C4—C3114.5 (4)
N1—Ir1—C6113.88 (16)C5—C4—H4A108.6
C1—Ir1—Cl1163.18 (12)C5—C4—H4B108.6
C1—Ir1—Cl278.41 (12)Ir1—C5—H5114.5
C1—Ir1—Cl389.92 (14)C4—C5—Ir1110.0 (3)
C1—Ir1—C236.12 (16)C4—C5—H5114.5
C1—Ir1—C594.14 (18)C6—C5—Ir170.9 (3)
C2—Ir1—Cl1159.73 (12)C6—C5—C4124.1 (5)
C2—Ir1—Cl2114.52 (12)C6—C5—H5114.5
C2—Ir1—Cl393.37 (14)Ir1—C6—H6113.6
C2—Ir1—C579.33 (18)C5—C6—Ir173.0 (3)
C5—Ir1—Cl188.79 (13)C5—C6—H6113.6
C5—Ir1—Cl2113.44 (12)C5—C6—C7124.2 (5)
C5—Ir1—Cl3160.95 (12)C7—C6—Ir1112.4 (3)
C6—Ir1—Cl192.97 (14)C7—C6—H6113.6
C6—Ir1—Cl278.03 (13)C6—C7—H7A108.4
C6—Ir1—Cl3162.18 (12)C6—C7—H7B108.4
C6—Ir1—C179.97 (19)C6—C7—C8115.7 (4)
C6—Ir1—C287.1 (2)H7A—C7—H7B107.4
C6—Ir1—C536.15 (17)C8—C7—H7A108.4
C9—N1—Ir1175.1 (4)C8—C7—H7B108.4
Ir1—C1—H1114.7C1—C8—C7115.2 (4)
C2—C1—Ir172.3 (3)C1—C8—H8A108.5
C2—C1—H1114.7C1—C8—H8B108.5
C2—C1—C8122.3 (5)C7—C8—H8A108.5
C8—C1—Ir1110.8 (3)C7—C8—H8B108.5
C8—C1—H1114.7H8A—C8—H8B107.5
Ir1—C2—H2114.2N1—C9—C10178.4 (5)
C1—C2—Ir171.6 (3)C9—C10—H10A109.5
C1—C2—H2114.2C9—C10—H10B109.5
C1—C2—C3122.5 (5)C9—C10—H10C109.5
C3—C2—Ir1113.0 (3)H10A—C10—H10B109.5
C3—C2—H2114.2H10A—C10—H10C109.5
C2—C3—H3A108.6H10B—C10—H10C109.5
Ir1—C1—C2—C3106.1 (4)C3—C4—C5—Ir132.7 (5)
Ir1—C1—C8—C727.6 (5)C3—C4—C5—C647.3 (6)
Ir1—C2—C3—C410.1 (6)C4—C5—C6—Ir1101.7 (4)
Ir1—C5—C6—C7105.8 (4)C4—C5—C6—C74.2 (7)
Ir1—C6—C7—C83.1 (6)C5—C6—C7—C887.1 (6)
C1—C2—C3—C492.3 (5)C6—C7—C8—C120.8 (7)
C2—C1—C8—C754.0 (6)C8—C1—C2—Ir1103.8 (4)
C2—C3—C4—C529.0 (6)C8—C1—C2—C32.3 (7)
 

Acknowledgements

The open-access fee was provided by the Virginia Tech Open Access Subvention Fund.

References

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Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 71| Part 4| April 2015| Pages 371-373
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