Ligand-interchange reactions between M(iv) (M = Ti, V) oxide bis-acetylacetonates and halides of high-valent group 4 and 5 metals. A synthetic and electrochemical study

The reactions of M’O(acac)2[M’ = Ti, V; acac = acetylacetonato anion] with equimolar amounts of MF5 (M = Nb, Ta) in CH2Cl2 afforded Ti(acac)2F2, 1a, and [V(acac)3][MF6] (M = Nb,4a;M=Ta,4b), respectively. MOF3 (M = Nb, 2a; M=Ta,2b) were co-produced from MF5/TiO(acac)2. The intermediate species [TaF4{OTi(acac)2}2][TaF6], 3, was intercepted in the course of the formation of 1a from TiO(acac)2/TaF5. NbCl5 reacted with TiO(acac)2 yielding selectively the previously reported [NbO(acac)Cl2]x, 5, and Ti2(acac)2(μ-Cl)2Cl4, 6. Complex 6 was alternatively obtained from the addition of a two-fold excess of TiCl4 to VO(acac)2. The 1 : 1 reactions of TiX4 (X = F, Cl) with TiO(acac)2 in dichloromethane gave Ti(acac)2X2 (X = F,1a; X = Cl, 1b) and TiOX2 (X = F, 7a; X = Cl, 7b). The 1 : 1 combination of TiX4 (X = F, Cl) with VO(acac)2 led to 1a, band VOX2 (X = F, 8a; X = Cl, 8b). The μ-oxido compounds (C6F5)3B–O–M’(acac)2(M’ = Ti, V) underwent fragmentation by [PF6]- in chlorinated solvent, yielding POF3, 9, and [B(C6F5)3F]-, 10, according to NMR studies; 1a and V(acac)3+, respectively, were detected as the metal-containing species. Electrochemical studies were carried out aiming at the full characterization of the products and the observation of possible degradation pathways.