1,10-Phenanthroline-5,6-dione as a building block for the synthesis of homo- and heterometallic complexes

1,10-Phenanthroline-5,6-dione (C12H6N2O2 (1)) reacts with V(η6-mesitylene)2 and Ti(η6-toluene)2 affording coordination compounds of general formula M(O,O′C12H6N2O2)3 (M=Ti (2); M=V (3)) which further react with TiCl4 or TiCp2(CO)2 yielding the tetrametallic species M(O,O′C12H6N2O2N,N′)3(M′Ln)3 (M=V, M′Ln=TiCl4 (4); M=Ti, M′Ln=TiCp2 (5); M=V, M′Ln=TiCp2 (6)). The complex salt [Fe(N,N′C12H6N2O2)3][PF6]2 (7) has been obtained from iron(II) chloride tetrahydrate and 1 in the presence of NH4PF6. The reaction of 7 with TiCp2(CO)2 affords the tetrametallic derivative [Fe(N,N′C12H6N2O2O,O′)3(TiCp2)3][PF6]2 (8). TiCl2(THF)2 reacts with MCp2(O,O′C12H6N2O2) to give MCp2(O,O′C12H6N2O2N,N′)TiCl2 (M=Ti (9); M=V (10)). By reaction of TiCp2(O,O′C12H6N2O2N,N′)TiCl2 (9) with C12H6N2O2, the bimetallic derivative TiCp2(O,O′C12H6N2O2N,N′)TiCl2(O,O′C12H6N2O2) (11) has been prepared, which readily adds to TiCl4, to give the trimetallic titanium derivative TiCp2(O,O′C12H6N2O2N,N′)TiCl2(O,O′C12H6N2O2N,N′)TiCl4 (12). VCp2(O,O′C12H6N2O2N,N′)TiCl2 (10) reacts with the tris-chelate iron(II) cation 7 affording the heptametallic cationic complex [Fe(N,N′C12H6N2O2O,O′)TiCl2(N,N′C12H6N2O2O,O′)VCp2]3 +2 isolated as the hexafluorophosphate 13.