trans-[Fe(cyclam)(C2R)2]+: A New Family of Iron(III) Bis-Alkynyl Compounds
摘要:
We previously communicated the preparation and characterization of two trans-[Fe(cyclam)(C CR)(2)]OTf compounds, 2b and 2c (where cyclam = 1,4,8,11-tetraazacyclotetradecane, R = -(SiPr3)-Pr-i (2b) or -Ph (2c), and OTf = trifluoromethanesulfonate), which were the first examples of Fe(III) bis-alkynyl complexes. In this work, the series has been expanded to include R = -H (2a), -C2SiMe3 (2d), -C4SiMe3 (2e), and -Fc (2f), which were prepared from the reaction between cis/trans-[Fe(cyclam)(OTf)(2)]OTf (1) and LiC CR (NaC CH for 2a). Compounds 2a-2f were characterized by spectroscopic/voltammetric techniques as well as high-resolution mass spectrometry (HR-MS). The trans-orientation of the alkynyl ligands were established from the single-crystal X-ray diffraction studies of 2b-2d. Furthermore, the electronic structures of the model compounds 2a'(+), 2d'(+), and 2e'(+) were analyzed with density-functional calculations, which revealed significant d pi-pi(C C) interactions.