New Iron(III) Bis(acetylide) Compounds Based on the Iron Cyclam Motif

New trans-[Fe(cyclam)(CCR)2]OTf compounds 2a/2b [cyclam = 1,4,8,11-tetraazacyclotetradecane, R = SiiPr3 (a) or Ph (b), and OTf = trifluoromethanesulfonate] were prepared from the reaction between trans-[Fe(cyclam)(OTf)2]OTf (1) and LiCCR. The trans arrangement of the acetylide ligands in 2 was established from the X-ray diffraction study of 2a, and the density functional theory calculations revealed significant dπ–π(CC) interactions.