Spectroscopy, Molecular Structure, and Electrochemistry of Rhenium(V) Oxo and Imido Complexes of 1,4,8,11-Tetraazacyclotetradecane (cyclam)

Yu Pey Wang, Chi Ming Che, Kwok Yin Wong, Shie Ming Peng

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Abstract

trans-[ReO2(cyclam)]ReO4·½ H2O trans- [ReO(OEt) (cyclam)] (C1O4)2, and trans- [Re(NPh)(OH)(cyclam)] (ClO4)2(cyclam = 1,4,8,11 -tetraazacyclotetradecane) were prepared and structurally characterized by X-ray crystallography. The structure of trans- [ReO2(cyclam)]ReO4·½H2O is quite similar to that of the previously reported trans-[ReO2-(cyclam)]Cl and trans-[ReO2(cyclam)]PF6. Crystal data: trans-[ReO2(C10H24N4)]ReO4·½H2O, M = 676.74, orthorhombic, space group Pnma, a = 17.717(5) Å, b = 17.073(4) Å, c = 5.466(2) Å, V= 1653.4(9) Å3, Z = 4, dcalcd= 2.719 g cm−3, μ(Mo Kα) = 14.86 mm−1; trans-[ReO(OEt)(C10H24N4)](ClO4)2, M = 646.49, orthorhombic, space group P212121, a = 8.869(4) Å, b = 13.850(3) Å, c = 17.681(3) Å, V= 2172(1) Å3, Z = 4, dcalcd= 1.977 g cm−3, μ(Mo Kα) = 5.97 mm−1; trans-[Re(NPh)(OH)(C10H24N4)](ClO4)2, M = 693.55, orthorhombic, space group Pnma, a = 17.651(6) Å, b = 15.702(5) Å, c = 8.695(2) Å,V= 2410(1) Å3, Z = 4, dcalcd= 1.912 g cm−3, μ(Mo Kα) = 5.50 mm−1. The rhenium-oxo bond distances in trans-[ReO2(cyclam)]+and trans-[ReO(OEt)-(cyclam)]2+are 1.775(9) and 1.643(9) Å, respectively. The UV-vis spectrum of trans-[ReO2(cyclam)]+shows two ligand field transitions at 423 and 530 nm. For trans-[ReO(OEt)(cyclam)]2+, the corresponding ligand field bands redshiftto481 and625nm. trans-[Re(NPh)(OH)(cyclam)]2+isstableinaqueousmedium. The measured ReNPh distance of 1.731(9) Å and Ress=N—Ph bond angle of 176.2(8)∘are consistent with the metal-imido formulation. The cyclic voltammogram of trans- [ReO2(cyclam)]+in aqueous medium shows a quasi-reversible 2H+−2e−couple corresponding to the reduction of Re(V) to Re(III). Both trans-[ReO(OEt)(cyclam)]2+and trans-[Re(NPh)-(OH)(cyclam)]2+show a le−reduction wave in acetonitrile at potentials of −1.0 and −1.4 V vs SCE, respectively. E° of the trans-[Rev(NPh)(OH)(cyclam)]2+/trans-[ReIV(NPh)(OH)(cyclam)]2+couple is smaller than that of trans-[RevO(OEt)(cyclam)]2+/trans-[ReIVO(OEt)(cyclam)]+.
Original languageEnglish
Pages (from-to)5827-5832
Number of pages6
JournalInorganic Chemistry
Volume32
Issue number25
DOIs
Publication statusPublished - 1 Jan 1993

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry

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