Synthetic control of the cis/trans geometry of [M(cyclam)(CCR)(2)]OTf complexes and photophysics of cis-[Cr(cyclam)(CCCF3)(2)]OTf and cis-Rh(cyclam)(CCCF3)(2)]OTf

摘要

During the synthesis of alkynyl complexes of the type [Cr(cyclam)(CCR)(2)]OTf from cis-[Cr(cyclam)(OTf)(2)] OTf, a cis to trans isomerization occurs that is dependent on the identity of the ether solvent. The isomerization occurs to a significant extent in THF, yielding greater than 80% of the trans isomer, whereas in diethyl ether this isomerization occurs to a lesser extent. Though some base catalyzed isomerization of the final alkynyl product occurs, the data herein supports that the majority of the isomerization occurs during the triflate to alkynyl ligand exchange. It is also demonstrated that 1,1,1,3,3-pentafluoropropane can be used in place of the more expensive 1,1,1-trifluoropropyne for the syntheses of the trifluoropropynyl complexes, cis/trans-IM(cyclam)(CCCF3)(2)OTf. The methodologies developed are used to prepare the previously unreported cis-IM(cyclam)(CCCF3)(2)OTf complexes (where M = Cr3+ and Rh-3). Upon photoexcitation, the Cr3+ complex is emissive (738 nm) in room temperature acetonitrile with lifetimes of 24 is and 122 is in air saturated and nitrogen purged solutions respectively. The corresponding Rh3+ complex is non-emissive. (c) 2014 Elsevier BY. All rights reserved.