The icosahedral [M@Pb 12 ] 3À (M = Co(1), Rh(2), Ir(3)) cluster ions were prepared from K 4 Pb 9 and Co(dppe)Cl 2 (dppe = 1,2-bis(diphenylphosphino)ethane)/[Rh(PPh 3 ) 3 Cl]/[Ir-(cod)Cl] 2 (cod = 1,5-cyclooctadiene), respectively,i nt he presence of 18-crown-6/ 2,2,2-cryptand in ethylenediamine/toluene solvent mixtures. The [K(2,2,2-cryptand)] + salt of 1 and the [K(18-crown-6)] + salt of 3 were characterized via X-ray crystallography; the ions 1 and 3 are isostructural and isoelectronic to the [Rh@Pb 12 ] 3À (2)i on as well as to the group 10 clusters [M'@Pb 12 ] 2À (M' = Ni, Pd, Pt). The ions are all 26-electron clusters with nearp erfect icosahedral I h point symmetry.C lusters 1-3 show record downfield 207 Pb NMR chemicals hifts duet os-aromaticity of the cluster framework. Calculated and observed 207 Pb NMR chemical shifts and 207 Pb-x M J-couplings ( x M = 59 Co, 103 Rh, 193 Ir) are in excellent agreement and DFT analysis shows that the variations of 207 Pb NMR chemical shifts for the [M@Pb 12 ] 2, 3À ions (M = Co, Rh, Ir,N i, Pd, Pt) are mainly governed by the perpendicularly oriented s 11 component of the chemical shift anisotropy tensor. The laser desorption ionization time-of-flight (LDI-TOF) mass spectra contain the molecular ions as well as several new gas phase clusters derived from the parents. The DFT-minimized structures of these ions are described.[a] Dr.