Synthesis of the labile rhenuim(I) complexes fac-Re(CO)3(L)[κ2-O,O-FcC(O)CHC(O)Me] (where Fc = ferrocenyl; L = THF, H2O, alkyne) and alkyne addition to the diketonate ligand

Publication date: Available online 22 June 2018Source: Journal of Organometallic ChemistryAuthor(s): Silvia Atim, Li Yang, Volodymyr Nesterov, Xiaoping Wang, Michael G. RichmondAbstractRefluxing equimolar amounts of 1-ferrocenyl-1,3-butanedione (Fcacac) with BrRe(CO)5 in THF yielded the labile solvent complex fac-Re(CO)3 (THF)[κ2-O,O-FcC(O)CHC(O)Me] (1) in 80% isolated yield. 1 may also be prepared in quantitative yield using fac-BrRe(THF)2(CO)3 as the starting rhenium complex. The THF molecule in 1 is replaced by H2O during chromatographic purification to furnish the corresponding aqua complex fac-Re(CO)3(H2O)[κ2-O,O-FcC(O)CHC(O)Me] (2) while the reaction of 1 with PPh3 gives fac-Re(CO)3(PPh3)[κ2-O,O-FcC(O)CHC(O)Me] (3). Treatment of 1 with the terminal alkynes phenylacetylene and methyl propiolate proceeds rapidly at room temperature to give the π intermediates fac-Re(CO)3 (alkyne)[κ2-O,O-FcC(O)CHC(O)Me] [4 (PhC≡CH); 6 (MeO2CCCH)] that are not stable and undergo a 1,4-addition with regiospecific alkyne attack at the γ-methine site of the Fcacac moiety to afford fac-Re(CO)3 [κ3-C,O,O-FcC(O)CH(E-PhC = CH)C(O)Me] (5) and fac-Re(CO)3 [κ3-C,O,O-FcC(O)CH(Z-HC=CCO2Me)C(O)Me] (7). The solid-state structure for 5 and 7 was established by X-ray crystallography, and the computed mechanisms that account for the formation of these two products from 1 and alkyne are presented. 1 reacts with the internal alkyne dimethyl acetylenedicarboxylate (DMAD) to furnish the novel dime...

Source: Journal of Organometallic Chemistry - July 11, 2018 Category: Chemistry Source Type: research