Crystal structure of [1,3-bis(2,4,6-trimethylphenyl)imidazolidin-2-ylidene]dichlorido(2-{[(2-methoxyethyl)(methyl)amino]methyl}benzylidene)ruthenium

The title compound [RuCl2(C33H44N3O)] is an example of a new generation of N,N-dialkyl metallocomplex ruthenium catalysts with an N→Ru coordination bond in a six-membered chelate ring.


Chemical context
Over the past decades, significant progress has been made in the conceptualization of methodology of organometallic catalytic systems for olefin metathesis (for selected reviews and books on the topic, see : Grela, 2014;Ogba et al., 2018;Mukherjee et al. 2018;Tsedalu, 2021;Cope ´ret et al., 2021).This has made it possible to successfully overcome some of the limitations that initially prevented the integration of ruthenium catalysts in both laboratory practice and industry.The list of such areas includes production of bioactive substances with a desired selectivity of the resulting double bond, obtaining highly functionalized organic compounds, and the synthesis of new materials including polymers (Pederson et al., 2002;Kozłowska et al., 2014;Eivgi et al., 2020).Complexes including a six-membered chelate ruthenium ring are effective catalysts for various types of olefin metathesis reactions (Polyanskii et al., 2019a,b;Kumandin et al., 2020Kumandin et al., , 2023;;Antonova et al., 2020;Vasilyev et al., 2023).On the other hand, the catalytic activity of metal complexes is dictated by the ligands, while the coordination environment of the metal center and ligands can be decorated by attaching different non-covalent bond donor or acceptor substituents for the regulation of the structure and the reactivity of the catalysts (Gurbanov et al., 2022a,b;Mahmoudi et al., 2017a,b;Mahmudov et al., 2013Mahmudov et al., , 2023)).This work proposes a method for obtaining a new chelate complex from the commercially available precursors [RuCl 2 (1,3-bis(2,4,6-trimethylphenyl)imidazoline-2-ylidene)(3-phenylindenylide-1-ene)(pyridine)] and styrene 2-methoxy-N-methyl-N-(2-vinylbenzyl)ethan-1amine.By X-ray analysis, it was proved that this complex is a trans-isomer, relative to the arrangement of the two chlorides.

Structural commentary
The Ru atom in the title compound is pentacoordinated to two C, one N and two Cl atoms (Fig. 1, Table 1).The Addison parameter is used to describe the distortion of the coordination geometry and is defined as � (difference between two largest angles / 60 for five-coordinated metal centers), allowing the distinction between trigonal-bipyramidal (ideally � = 1) and square-pyramidal (ideally � = 0) geometries (Addison et al., 1984).For the title complex, � = 0.244, which is between these two geometries (Fig. 2), [� = 0.09 for minor disorder Cl2 0 and the coordination geometry is closer to square pyramidal].The dihedral angle between the planes of the trimethylphenyl rings is 26.34 (10) � .The complex shows the usual trans arrangement of the two chlorides, with Ru-Cl bond lengths of 2.3515 (8) and 2.379 (7) A ˚, and a Cl-Ru-Cl angle of 158.02 (3) � .The bond lengths and angles about the Ru atom are in good agreement with those reported for similar compounds (see Database survey section).

Supramolecular features
The crystal structure of the title complex includes intra-and intermolecular C-H� � �Cl interactions (Tables 2 and 3).In the ten intramolecular C-H� � �Cl interactions, the H� � �Cl distances vary from 2.56 to 2.94 A ˚, while the C-H� � �Cl angles vary from 110 to 129 � .The intermolecular C-H� � �Cl interactions in the title complex are shown in Fig. 3.A weak intramolecular C-H� � �� interaction is also observed.

Database survey
The compounds [1,3-bis(2,4,6-trimethylphenyl) The molecular structure of the title complex with displacement ellipsoids for the non-hydrogen atoms drawn at the 30% probability level.Only the major component of the disorder is shown for clarity.

Figure 2
A view of the coordination geometry about the Ru atom, which lies between square-based pyramidal and trigonal-bipyramidal for major disorder component Cl2.ruthenium (XACYOQ; Slugovc et al., 2004) show similar metal-atom geometries to the title compound.
In XACYOQ, molecules are linked by C-H� � �Cl, C-H� � �� and �-�-stacking interactions.In the crystal structures of TITTUO and DULVOW, intermolecular �-� stacking is an important factor and these interactions form a framework-like structure containing channels that extend along the b and c axes, respectively (Samojłowicz et al., 2009).

Synthesis and crystallization
In a Schlenk flask, ruthenium precursor complex [RuCl 2 (1,3bis(2,4,6-trimethylphenyl)imidazoline-2-ylidene)(3-phenylindenylide-1-ene)(pyridine)] (200 mg, 0.26 mmol, 1.0 equiv.) was dissolved in dry toluene (4 mL) under an argon atmosphere.Then the styrene (0.31 mmol, 1.2 equiv.) was added in an argon stream, after that the flask was sealed with a screw cap and heated at 353 K for 1 h.The reaction mixture was placed in a freezer (253 K) for 30 min.The precipitate was filtered off and washed sequentially with hexane (3 � 5 mL) and methanol (3 � 3 mL), both cooled to 253 K, to give the title complex as a green powder after drying under vacuum for 2 h.A single crystal was obtained by slow crystallization from a hexane/chloroform mixture at 298 K.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 4.All C-bound H atoms were included in the refinement using the riding-model approximation with C-H distances of 0.95-0.99A ˚, and with U iso (H) = 1.2 or 1.5U eq (C).The measurements of the 0 0 2, 1 0 1, 0 1 1,  1 0 1 and 1 1 The packing of the title complex, showing the C-H� � �Cl interactions along the a-axis direction as dashed lines.For clarity, only the major component of the disorder and the hydrogen atoms involved in the bonding are shown.

Special details
Geometry.All esds (except the esd in the dihedral angle between two l.s.planes) are estimated using the full covariance matrix.The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry.An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s.planes.

Table 3
Summary of short interatomic contacts (A ˚) in the title compound.

Table 4
Experimental details.