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Unexpected One-Electron Oxidation of a Secondary Phosphite Selenide Cp(CO)2FeP(Se)(OiPr)2 by GaCl3 and InCl3 – Rare Examples of Di- and Triselenide Formation



The reactions of the neutral phosphonoselenoate [Cp(CO)2FeP(Se)(OiPr)2] (1) with Lewis acids (GaCl3, InCl3) produce dicationic complexes [{Cp(CO)2FeP(OiPr)2}2Sen][GaCl4]2, [n = 2 (2), 3 (3)] and [{Cp(CO)2FeP(OiPr)2}2Sen][InCl4]2 [n = 2 (4), 3 (5)] in good yields; the complexes comprise an Se3 (or Se2) chain that bridges two FpP(OiPr)2 groups [Fp = Cp(CO)2Fe]. These compounds are the one-electron oxidation products of secondary phosphite selenide 1 by group 13 (Ga, In) trichlorides. On the other hand, the reaction of GaCl3 with (iPrO)2PSe2 (dsep) yields only the Lewis adduct tris(O,O-diisopropyldiselenophosphate)gallium (6). The 31P NMR spectrum of 6 at 183 K reveals that the gallium(III) center is surrounded by one chelating and two pendant dsep ligands, which is in line with the obtained X-ray structure. In addition, the two-electron oxidation of 1 leads to phosphite [Cp(CO)2FeP(O)(OiPr)2] formation.