Evidence for dissociative photosubstitution reactions of (Ru(trpy)(bpy)(NCCH sub 3 )) sup 2+. Crystal and molecular structure of (Ru(trpy)(bpy)(py))(PF sub 6 ) sub 2 ter dot (CH sub 3 ) sub 2 CO

Journal Article · Wed Feb 20 04:00:00 EST 1991 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00004a013· OSTI ID:5908580

Hecker, C R; Fanwick, P E; McMillin, D R ^[1]

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1. Purdue Univ., West Lafayette, IN (USA)

In acetonitrile and in the presence of appropriate nucleophiles, the complex (Ru(trpy)(bpy)(NCCH{sub 3})){sup 2+} undergoes a ligand substitution reaction when irradiated into the metal-to-ligand absorption band system (trpy = 2,2{prime}:6{prime},2{double prime}-terpyridine, and bpy = 2,2{prime}-bipyridine.) At 25C quantum yields for displacement of the acetonitrile ligand are 0.0013 (1), 0.0013 (1), and 0.0026 (5) for 1.0 M solutions of pyridine, 4-phenylpyridine, and 2-methylpyridine, respectively. No photochemistry is observed for the osmium(II) analogue, and all findings can be understood in terms of a dissociative reaction mechanism involving a reactive {sup 3}d-d state. The {sup 3}d-d state is accessed from a {sup 3}CT state, which is emissive below ca. 180 K. From measurements of the temperature dependence of the emission lifetime, the barrier to population of the {sup 3}d-d state is approximately 1,500 cm{sup {minus}}. Finally, the crystal structure of (Ru(trpy)(bpy)(py))(PF{sub 6}){sub 2}{center dot}(CH{sub 3}){sub 2}CO has been determined with a diffractometer. The compound crystallizes with two independent formula units in a triclinic unit cell, and the crystal structure is reported. The structure was solved by the full-matrix least-squares method, and after the final stage of refinement, R = 0.0055. There is evidence of interligand steric strain within the coordination sphere, and the bpy ligand is coordinated asymmetrically with a difference in Ru-N bond lengths of about 0.04 {Angstrom}. The internal strain probably explains why the authors have been unable to prepare the 2-methylpyridine analogue by standard methods.

• OSTI ID: 5908580
• Journal Information: Inorganic Chemistry; (United States), Journal Name: Inorganic Chemistry; (United States) Vol. 30:4; ISSN 0020-1669; ISSN INOCA
• Country of Publication: United States
• Language: English

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ALKANES
AROMATICS
AZINES
BIPYRIDINES
CHEMICAL PREPARATION
CHEMISTRY
COMPLEXES
CRYSTAL STRUCTURE
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EXPERIMENTAL DATA
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HYDROCARBONS
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NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOCHEMISTRY
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RUTHENIUM COMPLEXES
SYNTHESIS
TRANSITION ELEMENT COMPLEXES