Directed syntheses of multidecker sandwich complexes of the title classes, incorporating C2B3 bridging rings and C(5)Me(5) end rings, have been achieved based on the tailored triple-decker synthon Cp*Co(Et(2)C(2)B(3)H(2)Me)Co(Et(2)C(2)B(3)H(3))(2-) (I2-), the neutral (diprotonated) form of which is described in the preceding paper. Three-way reactions of I2-, the double-decker anions Cp*Co(Et(2)C(2)B(3)H(2)-5-A)(2-) (A = H or Me), and Co2+ ion in cold THF, with workup of the products in air, afforded the Co-4 pentadecker sandwiches Cp*Co(Et(2)C(2)B(3)H(2)A)M(Et(2)C(2)B(3)H(3))-CoH(Et(2)C(2)B(3)H(2)Me)CoCp* (3, M = Co, A = H; 4, M = CoH, A = Me; 5, M = Co, A = Me). A similar reaction employing Ni2+ gave the heterometallic Co3Ni pentadecker [Cp*Co(Et(2)C(2)B(3)H(2)Me)]2NiCoH(Et(2)C(2)B(3)H(3)) (6). Hexadecker sandwiches were obtained via treatment of I2- or I- with Co’f or Pt’+ ions, generating respectively the Cos species [Cp*Co(Et(2)C(2)B(3)H(2)Me)Co(Et(2)C(2)B(3)H(3))]2HxCo (7, x = 1; 8, x = 2) and the Co4Pt complex [Cp *Co(Et(2)C(2)B(3)H(2)Me)Co(Et(2)C(2)B(3)H(3))]Pt-2 (9) The pentadecker and hexadecker products were obtained as black, moderately air-stable solids in 5-20% individual isolated yields and characterized from their ESR or NMR, UV-visible, and mass spectra, elemental analysis, and an X-ray crystal structure determination on 8. Except for diamagnetic 4, all of these complexes are paramagnetic as shown by ESR spectroscopy. In several species the unpaired electrons appear to be extensively delocalized, while in others they are restricted to the region of the interior metal atoms. ESR and electronic spectra are consistent with assignments of the pentadeckers 3, 4, and 5 as 53, 54, and 53 valence electron (ve) systems, respectively, with each of the 53 ve species having one unpaired electron. Compound 6, though a 54 ve system isoelectronic with 4, is nevertheless paramagnetic. ESR data on the hexadecker sandwiches 7 and 9 are consistent with 64 ve systems having two unpaired electrons, and strong spin-spin interaction is indicated between neighboring Co(IV) centers in 7. Complex 8, with two CoH protons, is formulated as a 65 ve species with one unpaired electron and is the largest multidecker sandwich to be confirmed by X-ray crystallography. The stack is somewhat bowed, with Co-Co-Co angles that deviate by 10-12 degrees from linearity. One of the two cobalt-bound protons was located and refined, and was revealed to be an eta(1)-H ligand on Co, with no apparent bonding interaction with other cluster atoms. Crystal data for 8 : space group P (1) over tilde$$; a = 13.434(2) Angstrom, b = 17.418(3) Angstrom, c = 13.430(2) Angstrom, alpha = 100.82(1)degrees, beta = 97.11(1)degrees, gamma = 102.65(1)degrees; Z = 2; R = 0.069 for 4690 independent reflections having I > 3 sigma(I).