Catalysis by Pincer-Iridium Complexes. Breaking C-H Bonds, Making C-C Bonds, and Various Combinations Thereof

Sep­tem­ber 2018

Pro­fes­sor Alan S. Gold­man
Depart­ment of Chem­istry and Chem­i­cal Biol­o­gy, Rut­gers — The State Uni­ver­si­ty of New Jer­sey
E-mail: alan.​goldman@​rutgers.​edu, Web: http://​ccb​.rut​gers​.edu/​g​o​l​d​m​a​n​-​a​lan
Abstract: Irid­i­um com­plex­es have played a lead­ing role in the organometal­lic chem­istry of
alka­nes and unre­ac­tive C-H bonds since the incep­tion of the field 30 years ago. We have found
that “PCP”-pincer-ligated irid­i­um com­plex­es are par­tic­u­lar­ly effec­tive for the dehy­dro­gena­tion of
alka­nes and have incor­po­rat­ed this reac­tion into tan­dem sys­tems for sev­er­al cat­alyt­ic
trans­for­ma­tions based on dehy­dro­gena­tion. A close­ly relat­ed class of reac­tions that we are
explor­ing is dehy­dro­gena­tive cou­pling. More recent­ly we have turned atten­tion to irid­i­um
Phe­box com­plex­es. Although the (PCP)Ir and (Phebox)Ir units are for­mal­ly iso­elec­tron­ic, the
for­mer oper­ates via C-H acti­va­tion by Ir(I) while the lat­ter effects dehy­dro­gena­tion via Ir(III) (as
an acetate com­plex) and pos­si­bly Ir(V) inter­me­di­ates. Such a high-oxi­da­tion-state cat­alyt­ic cycle
offers advan­tages for many poten­tial appli­ca­tions of dehy­dro­gena­tion. In par­al­lel, how­ev­er, we
find that the low-oxi­da­tion-state (+I) chem­istry of (Phebox)Ir offers its own nov­el hydro­car­bon
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