title: Synthesis and characterization of [Ir(1,5-cyclooctadiene)(μ-H)]4: a tetrametallic Ir4H4-core, coordinatively unsaturated cluster.
abstract: Reported herein is the synthesis of the previously unknown [Ir(1,5-COD)(μ-H)](4) (where 1,5-COD = 1,5-cyclooctadiene), from commercially available [Ir(1,5-COD)Cl](2) and LiBEt(3)H in the presence of excess 1,5-COD in 78% initial, and 55% recrystallized, yield plus its unequivocal characterization via single-crystal X-ray diffraction (XRD), X-ray absorption fine structure (XAFS) spectroscopy, electrospray/atmospheric pressure chemical ionization mass spectrometry (ESI-MS), and UV-vis, IR, and nuclear magnetic resonance (NMR) spectroscopies. The resultant product parallels--but the successful synthesis is different from, vide infra--that of the known and valuable Rh congener precatalyst and synthon, [Rh(1,5-COD)(μ-H)](4). Extensive characterization reveals that a black crystal of [Ir(1,5-COD)(μ-H)](4) is composed of a distorted tetrahedral, D(2d) symmetry Ir(4) core with two long [2.90728(17) and 2.91138(17) Å] and four short Ir-Ir [2.78680 (12)-2.78798(12) Å] bond distances. One 1,5-COD and two edge-bridging hydrides are bound to each Ir atom; the Ir-H-Ir span the shorter Ir-Ir bond distances. XAFS provides excellent agreement with the XRD-obtained Ir(4)-core structure, results which provide both considerable confidence in the XAFS methodology and set the stage for future XAFS in applications employing this Ir(4)H(4) and related tetranuclear clusters. The [Ir(1,5-COD)(μ-H)](4) complex is of interest for at least five reasons, as detailed in the Conclusions section.
authors.affiliation: Department of Applied Cosmetology, Hungkuang University, Taichung, Taiwan 433.
authors.forename: Kuang-Hway
authors.initials: KH
authors.lastname: Yih
authors.forename: Isil K
authors.initials: IK
authors.lastname: Hamdemir
authors.forename: Joseph E
authors.initials: JE
authors.lastname: Mondloch
authors.forename: Ercan
authors.initials: E
authors.lastname: Bayram
authors.forename: Saim
authors.initials: S
authors.lastname: Özkar
authors.forename: Relja
authors.initials: R
authors.lastname: Vasić
authors.forename: Anatoly I
authors.initials: AI
authors.lastname: Frenkel
authors.forename: Oren P
authors.initials: OP
authors.lastname: Anderson
authors.forename: Richard G
authors.initials: RG
authors.lastname: Finke