화학공학소재연구정보센터
Journal of the American Chemical Society, Vol.139, No.40, 14292-14301, 2017
Heterobimetallic Silver-Iron Complexes Involving Fe(CO)(5) Ligands
Iron(0) pentacarbonyl is an organometallic compound with a long history. It undergoes carbonyl displacement chemistry with various donors (L), leading to molecules of the type Fe(CO)(x)(L)(5-x). The work reported here illustrates that Fe(CO)5 can also act as a ligand. The reaction between Fe(CO)5 with the silver salts AgSbF6 and Ag[B{3,5-(CF3)(2)C6H3}(4)] under appropriate conditions resulted in the formation of [(mu-H2O)AgFe(CO)(5)](2)[SbF6](2) and [B{3,5-(CF3)(2)C6H3}(4)]AgFe(CO)(5), respectively, featuring, heterobimetallic {Ag- Fe(CO)(5)}(+) fragments. The treatment of [B{3,5-(CF3)(2)C6H3}(4)]AgFe(CO)(5) with 4,4 '-dimethyl-2,2 '-bipyridine (Me(2)Bipy) and Fe(CO)(5) afforded a heterobimetallic [(Me(2)Bipy)AgFe(CO)(3)][B{3,5-(CF3)(2)C6H3}(4)] species with a Ag Fe(CO)(5) bond and a heterotrimetallic [{Fe(CO)(5)}(2)(mu-Ag)][B{3,5-(CF3)(2)C6H3}(4)] with a (CO)(5)Fe-Ag-Fe(CO)(5) core, respectively, illustrating that it is possible to manipulate the coordination sphere at silver while keeping the Ag Fe bond intact. The chemistry of [B{3,5-(CF3)(2)C6H3}(4)]AgFe(CO)(5) with Et2O and PMes(3) (Mes = 2,4,6-trimethylphenyl) has also been investigated, which led to [(Et2O)(3)Ag][B{3,5-(CF3)(2)C6H3}(4)] and [(Mes(3)P)(2)Ag][B{3,5-(CF3)(2)C6H3}(4)] with the displacement of the Fe(CO)(5) ligand. X-ray structural and spectroscopic data of new molecules as well as results of computational analyses are presented. The Fe Ag bond distances of these metal-only Lewis pairs range from 2.5833(4) to 2.6219(5) angstrom. These Ag-Fe bonds are of primarily an ionic/electrostatic nature with a modest amount of charge transfer between Ag+ and Fe(CO)(5). The (v) over bar (CO) bands of the molecules with Ag-Fe(CO)(5) bonds show a notable blue shift relative to those observed for free Fe(CO)(5), indicating a significant reduction in Fe -> CO back-bonding upon its coordination to silver(I).