Solution dynamics and gas-phase chemistry of Pd2@Sn 184-

Abstract

Sn94- reacts with Pd(PPh3)4 in ethylenediamine/toluene solvent mixtures in the presence of 2,2,2-cryptand to give the Pd2@Sn184- cluster as the K(2,2,2,-crypt)+ salt. The cluster is isostructural with Pd 2@Ge184- and has a nuclearity different from that of the Pt and Ni analogues, Ni2@Sn174- and Pt2@Sn174-. The Pd2@Sn 184- ion has a deltahedral capsulelike structure with 40 cluster bonding electrons and is the largest free-standing polystannide characterized to date. Like Pt2@Sn174-, the Pd2@Sn184- complex is highly dynamic in solution, showing a single 119Sn NMR resonance indicative of an intramolecular liquidlike dynamic exchange. LDI-MS studies of the crystalline sample show extensive fragmentation and the formation of five gas-phase cluster series: Snx- (1 < x < 12), PdSnx-1- (4 < x < 18), Pd2Snx-2- (6 < x < 21), Pd3Snx-3- (8 < x < 21), and Pd4Snx-4- (13 < x < 21). The most abundant ion in the gas phase is the PdSn10- cluster, which presumably has an Sn10 bicapped-square-antiprismatic structure with an endohedral Pd (e.g., Ni@Pb102-). © 2008 American Chemical Society.