Reversible CO-induced chloride shuttling in Rh(I) tweezer complexes containing urea-functionalized hemilabile ligands.
The urea moiety, which acts as a good hydrogen-bond donor, has been incorporated into a hemilabile phosphinoalkyl thioether ligand. Upon reaction of the ligand with a Rh(I) precursor, a tweezer complex with near-parallel planar urea moieties 2 forms. The host-guest interaction of 2 with Cl(-) has been characterized in solution and in the solid state. Cl(-) binding with the urea groups in 2 is retained under CO in nonpolar solvents to give a five-coordinate CO adduct 3. In polar solvents, CO binding to Rh(I) results in a Cl(-) shift from the urea host site to the Rh(I) metal center with a concomitant breaking of the Rh-S bonds. This is an unusual example of how two types of different interactions important in molecular recognition (ligand coordination to a metal and hydrogen bonding) can be regulated within one molecule through small-molecule coordination chemistry.
Department of Chemistry and the International Institute for Nanotechnology, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, USA.
Hyojong
H
Yoo
Chad A
CA
Mirkin
Antonio G
AG
DiPasquale
Arnold L
AL
Rheingold
Charlotte L
CL
Stern