Heteroatomic Molecular Clusters Derived from Group 15 Zintl Ion Cages: Synthesis and Isolation of [M2(HP7)2]2− (M = Ag, Au), Two Novel Cluster Anions Exhibiting Metallophilic Interactions

Ethylenediamine (en) solutions of K3P7 and 2,2,2-crypt (4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo[8.8.8]hexacosane) were reacted with the homoleptic group 11 complexes [M(nbe)3][SbF6] (M = Ag, Au; nbe = norbornene) yielding two novel cluster anions, [M2(HP7)2]2−, both of which were isolated in low crystalline yields as [K(2,2,2-crypt)]2[M2(HP7)2] (M = Ag (1) and Au (2)). Optimization of the reaction conditions by incorporation of a proton source (ammonium tetraphenylborate) and the replacement of the light-sensitive nbe adducts of silver and gold with the chloride salts MCl (M = Ag, Au) was found to greatly increase the yield and purity in which 1 and 2 were isolated. Compounds 1 and 2 were characterized by single crystal X-ray diffraction, electrospray ionization mass-spectrometry (ESI− MS), elemental analysis, and 1H and 31P NMR spectroscopy. Density functional theory (DFT) calculations on the cluster anions were also conducted.