TRIPOD-IRON AND TRIPOD-COBALT-COMPLEXES W ITH ACETONITRILE AS SUPPORTING LIGANDS (TRIPOD=RCH(2),C(CH(2)PPH(2))(3) R=H, PH)

The tripod ligands RCH(2)C(CH(2)PPh(2))(3) react with (CH3CN)(6)Fe(BF4 )(2) to yield the tripod-Fe(II) complexes RCH(2)C(CH(2)PPh(2))(3)Fe(CH 3CN)(3)(BF4)(2) (R = H, la; R = Ph, Ib). The octahedral low spin Fe(II ) compounds are shown by cyclic voltammetry to undergo reversible one electron oxidation at +1.47 V (vs. SCE) to give the corresponding Fe(I II) derivatives. In a similar way (CH3CN)(6)Co(BF4)(2) reacts with the same tripod ligands to produce the tripod-Co(II) complexes RCH(2)C(CH (2)PPh(2))(3)Co(CH3CN)(2)(BF4)(2) (R = H, 2a; R = Ph, 2b). The compoun ds are paramagnetic (2a, g = 2.123; 2b, g = 2.129). The structure of c omplex 2b shows that the tripod ligand is facially coordinated with on e longer (233.1 pm) and two shorter (about 222 pm) Co-P bonds. Reversi ble reduction is found for 2a at -0.30 V by cyclic voltammetry. The co mpounds have been characterized by spectroscopic and analytical techni ques including X-ray analyses.