Cleavage of a PN Bond in a Urea‐Containing (Ph 2 P(R)PPh 2 )‐Bridged Dinuclear Gold(I) Thiolate Complex by Fluoride and a Mechanistic Insight

A urea‐containing, (Ph 2 P(R)PPh 2 )‐bridged, dinuclear, gold(I) thiolate complex, [Au 2 {Ph 2 PN(C 6 H 4 OMe‐4)PPh 2 }(SC 6 H 4 NHCONHC 6 H 5 ) 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 PN bond hydrolysis, instead of the expected hydrogen‐bonding interactions with the urea receptor. Similar changes were observed for two other basic anions, AcO − and H 2 PO 4 − , 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 [Au 2 {Ph 2 PN(C 6 H 4 OMe‐4)PPh 2 }Cl 2 ] ( 2 ) indicate that F − assists the hydrolysis process via cleavage of the PN bond. DFT calculations were performed to study the reaction mechanism for the fluoride‐assisted PN bond hydrolysis of 2 ; these provide a better insight into the role of fluoride in the hydrolysis.