| Abstract
| - Ethylenediamine (en) solutions of K4Pb9 react with toluene solutions of ML4 (M = Pt, Pd, L =PPh3; M = Ni, L2 = COD) and 2,2,2-crypt to give M@Pb122- cluster anions (M = Pt (1), Pd (2), Ni (3)) asthe [K(2,2,2-crypt)]+ salts in low (Ni) to good (Pt) yields. The ions have near perfect Ih point symmetry andhave been characterized by X-ray diffraction, 207Pb NMR and LDI-TOF mass spectrometry studies. For M= Ni, the primary product formed is the D4d Ni@Pb102- cluster that has also been structurally characterized.The M@Pb102- clusters (M = Pd, Pt) and the new Zintl ions closo-Pb102- and closo-Pb122- were formed inthe gas phase but have not been detected in solution or the solid state. The structural trends of theseseries of clusters have been investigated through DFT calculations. The Ni@Pb102- cluster is dynamic onthe 207Pb NMR time scale at −45 °C and 104.7 MHz. The M@Pb122- ions show unusually deshielded207Pb NMR chemical shifts that presumably arise from σ-aromatic effects associated with their highsymmetries. In the solid state, the salts form superlattices of cations and anions (e.g. the AlB2 lattice of[K(2,2,2-crypt)]2[Pt@Pb12]) and are prototypes for “assembled cluster materials”.
|
