American Chemical Society
ic402048a_si_002.cif (28.63 kB)

Ring-Closing Metathesis and Nanoparticle Formation Based on Diallyldithiocarbamate Complexes of Gold(I): Synthetic, Structural, and Computational Studies

Download (28.63 kB)
posted on 2014-03-03, 00:00 authored by Saira Naeem, Stefano A. Serapian, Anita Toscani, Andrew J. P. White, Graeme Hogarth, James D. E. T. Wilton-Ely
The gold­(I) complexes [Au­{S2CN­(CH2CHCH2)2}­(L)] [L = PPh3, PCy3, PMe3, CNtBu, IDip] are prepared from KS2CN­(CH2CHCH2)2 and [(L)­AuCl]. The compounds [L2(AuCl)2] (L2 = dppa, dppf) yield [(L2)­{AuS2CN­(CH2CHCH2)2}2], while the cyclic complex [(dppm)­{Au2S2CN­(CH2CHCH2)2}]­OTf is obtained from [dppm­(AuCl)2] and AgOTf followed by KS2CN­(CH2CHCH2)2. The compound [Au2{S2CN­(CH2CHCH2)2}2] is prepared from [(tht)­AuCl] (tht = tetrahydrothiophene) and the diallyldithiocarbamate ligand. This product ring-closes with [Ru­(CHPh)­Cl2­(SIMes)­(PCy3)] to yield [Au2(S2CNC4H6)2], whereas ring-closing of [Au­{S2CN­(CH2CHCH2)2}­(PR3)] fails. Warming [Au2{S2CN­(CH2CHCH2)2}2] results in formation of gold nanoparticles with diallydithiocarbamate surface units, while heating [Au2(S2CNC4H6)2] with NaBH4 results in nanoparticles with 3-pyrroline dithiocarbamate surface units. Larger nanoparticles with the same surface units are prepared by citrate reduction of HAuCl4 followed by addition of the dithiocarbamate. The diallydithiocarbamate-functionalized nanoparticles undergo ring-closing metathesis using [Ru­(CHC6H4OiPr-2)­Cl2(SIMes)]. The interaction between the dithiocarbamate units and the gold surface is explored using computational methods to reveal no need for a countercation. Preliminary calculations indicate that the Au–S interactions are substantially different from those established in theoretical and experimental studies on thiolate-coated nanoparticles. Structural studies are reported for [Au­{S2CN­(CH2CHCH2)2}­(PPh3)] and [Au2{S2CN­(CH2CHCH2)2}2]. In the latter, exceptionally short intermolecular aurophilic interactions are observed.