TRIPOD LIGANDS WITH NEOPENTANE FRAME AND 2 DIFFERENT DONOR GROUPS CH3C(CH(2)PPH(2))(2)(CH(2)SR) - SYNTHESIS, STRUCTURE, REDOX CHEMISTRY, AND SPECTROSCOPY OF THE COMPLEXES TRIPODM(ORTHO-(X)(Y)C6H4)

Neopentane-based tripod ligands CH3C(CH(2)PPh(2))(2)(CH(2)Z) (Z = SBn, SH, S-) form pentacoordinate compounds [tripodM{ortho(X)(Y)C6H4}](m) 1-4 with ortho-phenylene-bridged coligands (X)(Y)C6H4 (X, Y = O-, S-, NH-) and Co(II), Co(III), Fe(II), or Fe(III) as the metal centers. The structures of these complexes are very similar to those observed for CH3C(CH(2)PPh(2))(3) as the tripod ligand. The redox potentials, howev er, for the corresponding one-electron oxidation and reduction process es are highly affected by the change in the tripod donor groups. Both potentials are shifted by a maximum of 700 mV upon replacement of a PP h(2) donor group by a sulfur-centered donor with the difference betwee n the potential of the oxidation step and the potential of the reducti on step staying almost constant for the whole series of compounds. Thi s difference of around 1.7 eV nicely corresponds to the energy of the HOMO-LUMO charge-transfer bands observed around 2 eV for all of the co mpounds. It may be inferred therefore that both observations (electron spectroscopy and cyclic voltammetry) refer in a similar way to the HO MO-LUMO gap of the compounds. It is shown that the formation of [tripo dCo(III){ortho(NH)(2)C6H4}](+)(BF4-) from ortho-phenylenediamine as th e source of the coligand involves precoordination of the amine Ligand followed by deprotonation of the coordinated Ligand. The capability of the tripodCo(II) template to form five-coordinate compounds with diam ines is further corroborated by the characterization of [tripodCo(en)] (2+) (5(2+)). In addition to the standard analytical data, EPR, UV/Vis , cyclovoltammetric data and X-ray structure analyses are presented wh ere appropriate.