Dendritic (phosphine)gold(I) thiolate complexes: assessment of the molecular size through PGSE NMR studies

The reactions of the tetraphosphine ligand DAB-G0-(PPh2)4 (DAB = 1,4-diaminobutane; G0 = Generation 0) or the octaphosphine ligand DAB-G1-(PPh2)8 (G1 = Generation 1) with the gold precursor [AuCl(tht)] (tht =tetrahydrothiophene) and the corresponding 4-substituted benzenethiolate lead to the (phosphine)gold(I) thiolate complexes [Au4(S-C6H4-X)4[(DAB-G0-(PPh2)4]] (X = F (11), MeO (12), Me (13) and NO2 (14)) and [Au8(S-C6H4-X)8[(DAB-G1-(PPh2)4]] (X = F (15), MeO (16), Me (17) and NO2 (18)). Complexes [Au4Cl4[(DAB-G0-(PPh2)4]] and [Au4(S-C6H4-OMe)4[(DAB-G0-(PPh2)4]] have been characterized by X-ray diffraction studies showing tetranuclear gold complexes in which the P-Au-X (X = Cl or S) structural units do not display aurophilic interactions. PGSE NMR studies of free ligands EN-G0-(PPh2)(4) (EN = 1,2-ethylenediamine), DAB-G0-(PPh2)(4), DAB-G1-(PPh2)8 and the (phosphine)gold(I) thiolate complexes permit the evaluation and comparison of the different molecular sizes depending on the ligand and the dendrimer generation.