The Pb122- and Pb102- zintl ions and the M@Pb122- and M@Pb102- cluster series where M = Ni, Pd, Pt

Ethylenediamine (en) solutions of K4Pb9 react with toluene solutions of ML4 (M = Pt, Pd, L = PPh3; M = Ni, L-2 = COD) and 2,2,2-crypt to give M@Pb-12(2-) cluster anions (M = Pt (1), Pd (2), Ni (3)) as the [K(2,2,2-crypt)](+) salts in low (Ni) to good (Pt) yields. The ions have near perfect I-h point symmetry and have been characterized by X-ray diffraction, Pb-207 NMR and LDI-TOF mass spectrometry studies. For M = Ni, the primary product formed is the D-4d Ni@Pb-10(2-) cluster that has also been structurally characterized. The M@Pb-10(2-) clusters (M = Pd, Pt) and the new Zintl ions closo-Pb-10(2-) and closo-Pb-12(2-) were formed in the gas phase but have not been detected in solution or the solid state. The structural trends of these series of clusters have been investigated through DFT calculations. The Ni@Pb-10(2-) cluster is dynamic on the Pb-207 NMR time scale at -45 degrees C and 104.7 MHz. The M@Pb-12(2-) ions show unusually deshielded Pb-207 NMR chemical shifts that presumably arise from sigma-aromatic effects associated with their high symmetries. 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@Pb-12]) and are prototypes for "assembled cluster materials".