Isomer-Selective Conversion of Au Clusters by Au(I) Thiolate Insertion

Isomer-selective conversion is achallenging goal inthe rationaldesign of Au clusters. Herein, we demonstrate the isomer-selectiveconversion of Au-18(ScC6)(14) (ScC6 = cyclohexanethiolate)into Au-24(SR)( x )(ScC6)(20-x ) in high yieldsby reactions with gold(I) thiolate (AuSR) complexes. Electrosprayionization mass spectrometry indicated that even numbers of AuSR unitsare inserted into Au-18(SR)( x )(ScC6)(14-x ) to generate Au-24(SR)( x )(ScC6)(20-x ) through intermediates Au-20(SR)( x )(ScC6)(16-x ) or Au-22(SR)( x )(ScC6)(18-x ).These results suggest that the number of constituent atoms in surfaceAu(I)SR oligomers only increases, while the number of electrons inan Au core is maintained. UV-vis analysis revealed the generationof one of two Au-24(SR)( x )(ScC6)(20-x ) isomersin the reactions of Au-18(ScC6)(14) with AuSR complexes, in contrast to the formationof both isomers by reactions with thiols. When the structures of Au-18(SR)(14) are compared with those of the Au-24(SR)(20) isomers, the partial structure in the Au coresis preserved in the isomer-selective conversion with AuSR complexes,regardless of the structures of the thiolate moiety. Herein, we discovered a geometric isomer-selective conversionof Au clusters by gold(I) thiolate (AuSR) insertion, one of the significantsynthetic routes for realizing rational designs. We demonstrated theisomer-selective conversion of Au-18(ScC6)(14) (ScC6 = cyclohexanethiolate)into the J-isomer out of two Au-24(SR)( x )(ScC6)(20-x ) isomers in high yields by the reactions with AuSR. The sameconversions were observed when using SR with & alpha;-methylene units,demonstrating the generality of isomer-selective conversion by AuSRinsertion.