Akademik Veri Yönetim Sistemi
INORGANIC CHEMISTRY, cilt.51, sa.5, ss.3186-3193, 2012 (SCI-Expanded)
Reported herein is the synthesis of the previously unknown [Ir(1,5-COD)(mu-H)](4) (where 1,5-COD = 1,5-cyclooctadiene), from commercially available [Ir(1,5-COD)Cl](2) and LiBEt3H 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)(mu-H)](4). Extensive characterization reveals that a black crystal of [Ir(1,5-COD)(mu-H)](4) is composed of a distorted tetrahedral, D-2d symmetry Ir-4 core with two long [2.90728(17) and 2.91138(17) angstrom] and four short Ir-Ir [2.78680 (12)-2.78798(12) angstrom] 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 Ir4H4 and related tetranuclear clusters. The [Ir(1,5-COD)(mu-H)](4) complex is of interest for at least five reasons, as detailed in the Conclusions section.