The first lanthanide(II) cationic species with coordination numbers 7, 8, and 9 have been structurally characterized. Mercury amalgams of the elemental lanthanides (Ln(Hg) where Ln = Sm, Eu, Yb) cleanly reduce Mn2(CO)10 and Co2(CO)8 in polydentate ethers to [Mn(CO)5]- and [CO(CO)4]- and are oxidized to solvated Ln(II) cations. In the bidentate ether DME (DME = 1,2-dimethoxyethane), [(DME)(x)Sm]2+ ions show some association with the metal carbonylate ions, based upon IR evidence. In the tridentate ether DIME (diethylene glycol dimethyl ether = DIME), IR data suggest that only the solvent-separated species [(DIME)3Ln] [CO(CO)4]2 (Ln : Sm = 3; Yb = 4) and [(DIME)3Ln] [Mn(CO)5]2 (Ln : Sm = 5; Yb = 6; Eu = 7) are formed. Structural characterizations confirm the presence of discrete [(DIME)3Sm]2+ and [(DIME)3Yb]2+ ions in 3 and 4, in which the DIME oxygens form a 9-coordinate tricapped trigonal prismatic geometry about Ln(II). Crystal data for 3 : space group P6(3), hexagonal; a = 11. 709(2) angstrom, c = 15.505 (3) angstrom; V = 1841.6 angstrom3; Z = 2; at -45-degrees-C; R(F) = 0.016 and R(wF) = 0.020. Crystal data for 4 : space group P6(3), hexagonal; a = 11.552(5) angstrom, c = 15.428(6) angstrom; V = 1783.1 angstrom3; Z = 2; at -60-degrees-C; R(F) = 0.066 and R(wF) = 0.083. The complex ion [(DIME)3SM]2+ in 3 and 5 and [(DIME)3Eu]2+ in 7 are significantly resistant to air oxidation compared to most other Ln(II) complexes. Insoluble reaction products are formed when Fe(CO)5 is reduced by lanthanide amalgams in ethers. Yb amalgam reductions of Fe(CO)5 in CH3CN produce the previously characterized [Hg{Fe(CO)4}2]2- ion, which is isolated as solid (CH3CN)4Yb[Hg{Fe(CO)4}2] (8). The complex (C5H5N)4Yb[Hg{Fe(CO)4}2](9) is isolated from a solution of 8 in C5H5N. The mixed-ligand complex [(C5H5N)5Yb(CH3CN)2][Hg{Fe(CO)4}2].2C5H5N (10) crystallizes from a cooled C5H5N/CH3CN solution containing 9.The cation of 10, [(C5H5N)5Yb(CH3CH)2]2+, has pentagonal bipyramidal geometry with the two CH3CN ligands trans on the apexes of the bipyramid. The C5H5N ligands form a "five-bladed propeller "configuration along the five equatorial verticies of the bipyramid. Crystal data for 10: space group P2(1)/m, monoclinic; a = 12.059(2) angstrom, b = 17.374(3) angstrom, c = 12.590(2) angstrom, beta = 99.44(2)degrees; V = 260 1.1 angstrom3; Z = 2; at -60-degrees-C; R(F) = 0.107 and R(wF) = 0.077. The mixed-ligand complex [(DIME)2Yb(CH3CN)2][Hg{Fe(CO)4]2] (11) crystallized from a cooled DIME/CH3CN solution containing 8. The cation of 11, [(DIME)2Yb(CH3CN)2]2+, has an 8-coordinate, distorted square-antiprismatic arrangement of ligands. Crystal data for 11: space group P2(1)2(1)2(1), orthorhombic; a = 9.576(5) angstrom, b = 15.156(3) angstrom, c = 23.918(5) angstrom; V= 3471.2 angstrom3; Z = 4; at -60-degrees-C; R(F) = 0.040 and R(wF) = 0.053. A metathesis reaction between (DIME)(x)Na2[B12H12] and (CH3CN)(x)YbCl2 in CH3CN yields the mixed-ligand complex [(DIME)Yb(CH3CN)5] [B12H12] (12). The coordination geometry around [(DIME)Yb(CH3CN)5]2+ in 12 is similar to that observed in 11, based on a square antiprism. Crystal data for 12: space group P2(1)/n, monoclinic; a = 12.168(2) angstrom, b = 14.880(2) angstrom, c = 17.615(3) angstrom, beta = 97.92(2)degrees; V = 3159.0 angstrom3; Z = 4; at -50-degrees-C; R(F) = 0.037 and R(wF) = 0.054.