Gold(I) and Silver(I) π‑Complexes with Unsaturated Hydrocarbons

Gold π-complexes
have been studied largely in the past 2
decades because of their role in gold-catalyzed reactions. We report
an experimental and theoretical investigation of the interaction between
a wide range of unsaturated hydrocarbons (alkanes, alkynes, alkadienes,
and allenes) and triphenylphosphine-gold­(I), triphenylphosphine-silver­(I),
and acetonitrile-silver­(I) cations. The bond dissociation energies
of these complexes were determined by mass spectrometry collision-induced
dissociations and their structures were studied by density functional
theory calculations and infrared photodissociation spectroscopy. The
results show that with the same phosphine ligand, gold binds stronger
to the π-ligands than silver and thereby activates the unsaturated
bond more effectively. Ligand exchange of phosphine by acetonitrile
at the silver complexes increases the binding energy as well as the
activation of the π-ligands. We also show that the substitution
of an unsaturated bond is more important than the bond type.

金π配合物（π-complexes）在过去二十年间得到了广泛研究，这源于其在金催化反应中的重要作用。本工作报道了一系列不饱和烃（烷烃、炔烃、二烯烃与丙二烯）与三苯基膦-金(I)、三苯基膦-银(I)及乙腈-银(I)阳离子之间相互作用的实验与理论研究。通过质谱碰撞诱导解离实验测定了此类配合物的键解离能，并借助密度泛函理论计算与红外光解离光谱对其结构进行了表征。研究结果表明，在使用相同膦配体的情况下，金与π配体的结合强度高于银，因此对不饱和键的活化效果更为显著。将银配合物中的膦配体替换为乙腈配体，可提升其结合能并增强对π配体的活化能力。本研究同时证实，不饱和键上的取代基效应相较于键型更为关键。