Bis­(η2-ethyl­ene)(η5-inden­yl)iridium(I)

Joseph S Merola

doi:10.1107/S1600536813025300

. 2013 Sep 21;69(Pt 10):m547. doi: 10.1107/S1600536813025300

Bis(η²-ethylene)(η⁵-indenyl)iridium(I)

Joseph S Merola ^a,^*

PMCID: PMC3790355 PMID: 24098177

Abstract

The asymmetric unit of the title compound, [Ir(C₉H₇)(C₂H₄)₂], consists of two independent molecules. The bonding between iridium and the five-membered ring of the indenyl ligand shows the usual asymmetry associated with the typical ring slippage responsible for the enhanced activity of indenyl metal compounds when compared with the analogous cyclopentadienyl metal compound. There are three short Ir—C bonds of 2.210 (3), 2.190 (4) and 2.220 (3) Å and two long Ir—C bonds to the C atoms that are part of the fused six-membered ring of 2.349 (4) and 2.366 (3) Å for one of the independent molecules [2.208 (4), 2.222 (3), 2.197 (4) Å for the short distances and 2.371 (3) and 2.358 (3) Å for the long distances in the second molecule]. This results in both indenyl ligands being slightly kinked, with dihedral angles of 6.8 (4)° and 6.5 (4)°.

Related literature

For the structures of the analogous rhodium(I) complex determined from single crystal X-ray data, see: CCDC:576585 (Marder et al., 1987 ▶); CCDC:567925 (Mlekuz et al., 1986 ▶). For a variable temperature NMR study of the title compound, see: Szajek et al. (1991 ▶). The structure of an η³-indenyliridium complex can be found in CCDC:563532 (Merola et al., 1986 ▶). For seminal discussions on the "indenyl effect" see: Hart-Davis et al. (1970 ▶); Rerek et al. (1983 ▶). The synthesis of [Ir(C₂H₂)₂Cl]₂ can be found in Herde et al. (1974 ▶).

Experimental

Crystal data

[Ir(C₉H₇)(C₂H₄)₂]
M _r = 363.45
Monoclinic,
a = 7.73182 (11) Å
b = 10.77708 (13) Å
c = 25.6818 (5) Å
β = 98.4034 (15)°
V = 2117.00 (5) Å³
Z = 8
Mo Kα radiation
μ = 12.57 mm⁻¹
T = 100 K
0.45 × 0.33 × 0.22 mm

Data collection

Agilent Xcalibur, Sapphire2 diffractometer
Absorption correction: gaussian (CrysAlis PRO; Agilent, 2013 ▶) T _min = 0.020, T _max = 0.142
55683 measured reflections
6917 independent reflections
6733 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.024
wR(F ²) = 0.055
S = 1.46
6917 reflections
253 parameters
H-atom parameters constrained
Δρ_max = 1.69 e Å⁻³
Δρ_min = −2.04 e Å⁻³

Data collection: CrysAlis PRO (Agilent, 2013 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2008 ▶); molecular graphics: OLEX2 (Dolomanov et al., 2009 ▶); software used to prepare material for publication: OLEX2.

Supplementary Material

Crystal structure: contains datablock(s) I. DOI: 10.1107/S1600536813025300/pk2496sup1.cif

e-69-0m547-sup1.cif^{(1.1MB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536813025300/pk2496Isup2.hkl

e-69-0m547-Isup2.hkl^{(1.5MB, hkl)}

Click here for additional data file.^{(3.1KB, mol)}

Supplementary material file. DOI: 10.1107/S1600536813025300/pk2496Isup3.mol

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

Acknowledgments

The author thanks the National Science Foundation for funds (CHE-01311288) for the purchase of the diffractometer. The author recognizes the payment of the open access fee by Virginia Tech University Libraries.

supplementary crystallographic information

1. Comment

The indenyl ligand has been shown to be very flexible in terms of its coordination to metals. An increased reactivity that is displayed by indenyl metal complexes compared with cyclopentadienyl complexes has been dubbed the "indenyl effect". The effect was first described by Mawby's group (Hart-Davis et al., 1970) and was further quantified by Basolo's group (Rerek et al., 1983) We have previously reported on the synthesis and structure of η³-indenyliridium complexes formed by reaction of an η⁵-indenyliridiumbis(olefin) complex and small phosphine ligands such as PMe₃ or PhPMe₂ (Merola et al., 1986). The smallest olefin complex of indenyl iridium, (η⁵-Indenyl)bis(η²-ethylene)iridium(I), 1, is the subject of this report. The thermal ellipsoid plot for both independent molecules of 1 is shown in figure 1. The most interesting aspects of the bonding are highlighted in table 1 showing the three short and two long bond distances of the "slipped" indenyl rings.

Figure 2 shows the "fold" of the indenyl ligand which imparts non-planarity of the 6-membered ring from the 5-membered ring. The angle between the planes defined by C1, C2 and C9 and that defined by C3, C8, C7, C4, C5 and C6 is 6.5 (4)° and 6.8 (4)° for the "A" and "B" molecules.

2. Experimental

[Ir(C₂H₂)₂Cl]₂ was synthesized by the reaction between [Ir(C₈H₁₄)₂IrCl]₂ and ethylene (Herde et al., 1974). The title compound was prepared by the reaction between lithium indenide and [Ir(C₂H₂)₂Cl]₂ in anhydrous THF. Crystals of the title compound were grown by the slow evaporation of a pentane solution. The title compound has also been reported previously prepared by this same method (Szajek et al., 1991).