“…A particular example is the ethereal complex, [CpFe-(CO) 2 (THF)]BF 4 [34] in which the labile tetrahydrofuran (THF) is coordinated to the metal centre through the oxygen atom. This complex has been proven to be an essential precursor in the synthesis of various cyclopentadienyliron complexes [4,[10][11][12][13][15][16][17][18][19][20]35], as well as catalysts in various organic syntheses such as the [2+2] cycloaddition of alkenes [36], Diels-Alder reactions [37,38], cyclopropanation [27,[31][32][33], epoxidation [29,30] and aziridination [25][26][27][28], among others [3,[22][23][24]27,29,39]. In all these reactions THF is easily displaced by the desired substrate to form either the desired intermediate or desired end product.…”