Cleavage of a P-N Bond in a Urea-Containing (Ph2 P(R)PPh2 )-Bridged Dinuclear Gold(I) Thiolate Complex by Fluoride and a Mechanistic Insight.
A urea-containing, (Ph2 P(R)PPh2 )-bridged, dinuclear, gold(I) thiolate complex, [Au2 {Ph2 PN(C6 H4 OMe-4)PPh2 }(SC6 H4 NHCONHC6 H5 )2 ] (1) was designed and synthesized and its photophysical and anion recognition properties studied. The results show that 1 has a high selectivity toward F(-) . Upon addition of F(-) , the yellow solution was decolorized, and drastic changes of emission and (1) H and (31) P{(1) H} NMR signals were observed. Interestingly, these changes are attributed to fluoride-assisted P-N bond hydrolysis, instead of the expected hydrogen-bonding interactions with the urea receptor. Similar changes were observed for two other basic anions, AcO(-) and H2 PO4 (-) , but to a much lesser extent; and these anions were found to bind to the urea receptor at the same time. On the other hand, Cl(-) was found to only bind to the urea moiety through hydrogen-bonding interactions. Further studies with the control complex [Au2 {Ph2 PN(C6 H4 OMe-4)PPh2 }Cl2 ] (2) indicate that F(-) assists the hydrolysis process via cleavage of the P-N bond. DFT calculations were performed to study the reaction mechanism for the fluoride-assisted P-N bond hydrolysis of 2; these provide a better insight into the role of fluoride in the hydrolysis.
Institute of Molecular Functional Materials (Area of Excellence Scheme, University Grants Committee (Hong Kong)).|Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong (P.R. China).
Xiaoming
X
He
Institute of Molecular Functional Materials (Area of Excellence Scheme, University Grants Committee (Hong Kong)).|Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong (P.R. China).
Wai Han
WH
Lam
Institute of Molecular Functional Materials (Area of Excellence Scheme, University Grants Committee (Hong Kong)).|Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong (P.R. China).
Eddie Chung-Chin
EC
Cheng
Institute of Molecular Functional Materials (Area of Excellence Scheme, University Grants Committee (Hong Kong)). wwyam@hku.hk.|Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong (P.R. China). wwyam@hku.hk.
Vivian Wing-Wah
VW
Yam
anion probes; gold; hydrolysis; reaction mechanisms; urea receptors