Syntheses and Structures of Dinuclear Gold(I) Dithiophosphonate Complexes and the Reaction of the Dithiophosphonate Complexes with Phosphines: Diverse Coordination Types

The dinuclear gold(I) dithiophosphonate complex, [Au2(dtp)2] (1), where dtp = [S2P(R)(OR‘)]- with R = p-C6H4OCH3; R‘= c-C5H9, has been synthesized and its reaction studied with the phosphine ligands PPh3 and Ph2P(CH2)nPPh2 (n = 1−4). Compound 1 contains two gold atoms homobridged by the anionic dithiophosphonate ligand,
forming an eight-membered ring complex in a chair form. After the reaction of 1 with diphosphine ligands, the
dinuclear open-ring complexes Au2(dppm)(dtp)2 (2), Au2(dppe)(dtp)2 (3), Au2(dppp)(dtp)2 (4), Au2(dppb)(dtp)2 (5)
were formed (dppm = diphenylphosphinomethane; dppe = diphenylphosphinoethane; dppp = diphenylphosphinopropane; dppb = diphenylphosphinobutane). The reaction with dppm is stoichiometry-dependent. Thus, when 1
reacts with 2 equiv of dppm, the ionic complex [Au2(dppm)2(dtp)]dtp forms. This dtp counterion was exchanged
with tetrafluoroborate to yield [Au2(dppm)2(dtp)]BF4, the crystallization of which afforded two interconvertible isomers,
6-yellow and 7-white. Reaction of 1 with PPh3 affords the tetracoordinate mononuclear complex [Au(dtp)(PPh3)2]
(8). The molecular structures of 1−8 were confirmed by X-ray crystallography and show multiple coordination
modes and geometries. The crystal structures of 1 and its reaction products with dppm (2, 6, 7) show short
intramolecular Au···Au aurophilic bonding interactions of 2.95−3.10 Å while no intermolecular interactions were
discernible. However, reaction products of 1 with longer-chain Ph2P(CH2)nPPh2 ligands, n = 2−4, exhibit structures
that lack both intra- and intermolecular Au···Au interactions.

本研究合成了双核金(I)二硫代膦酸酯配合物（dinuclear gold(I) dithiophosphonate complex）[Au₂(dtp)₂]（1），其中dtp（二硫代膦酸根阴离子，dithiophosphonate anion）为[S₂P(R)(OR‘)]⁻，R为对甲氧基苯基（p-C₆H₄OCH₃），R‘为环戊基（c-C₅H₉），并研究了其与膦配体PPh₃（三苯基膦，triphenylphosphine）及Ph₂P(CH₂)ₙPPh₂（n=1~4）的反应。配合物1中两个金原子被该阴离子型二硫代膦酸酯配体同桥联，形成具有椅式构象的八元环配合物。当配合物1与双齿膦配体（diphosphine ligands）反应后，得到系列双核开环配合物：Au₂(dppm)(dtp)₂（2）、Au₂(dppe)(dtp)₂（3）、Au₂(dppp)(dtp)₂（4）及Au₂(dppb)(dtp)₂（5），其中dppm（二苯基膦甲烷，diphenylphosphinomethane）、dppe（二苯基膦乙烷，diphenylphosphinoethane）、dppp（二苯基膦丙烷，diphenylphosphinopropane）、dppb（二苯基膦丁烷，diphenylphosphinobutane）。该反应与dppm的投料比具有化学计量依赖性：当配合物1与2当量的dppm反应时，生成离子型配合物[Au₂(dppm)₂(dtp)]dtp；将该配合物中的dtp抗衡离子交换为四氟硼酸根（tetrafluoroborate），得到[Au₂(dppm)₂(dtp)]BF₄，其结晶过程可得到两种可相互转化的异构体：黄色异构体6与白色异构体7。配合物1与PPh₃反应则得到四配位单核配合物[Au(dtp)(PPh₃)₂]（8）。通过X射线单晶衍射（X-ray crystallography）确认了配合物1~8的分子结构，其展现出多种配位模式与配位几何构型。配合物1及其与dppm的反应产物（2、6、7）的晶体结构中存在键长2.95~3.10 Å的分子内Au···Au亲金相互作用（aurophilic bonding interactions），但未观察到明确的分子间相互作用；而配合物1与长链Ph₂P(CH₂)ₙPPh₂配体（n=2~4）的反应产物，则不存在分子内及分子间的Au···Au相互作用。