Syntheses and crystal structures of complexes [L′O(H2O)V(µ-O)WO2L]Cl(ClO4) and [L′(acac)MoIII(µ-O)MoVIO2L′][BPh4]2(L,L′= 1,4,7-triazacyclononane and its 1,4,7-trimethyl derivative; acac = pentane-2,4-dionate)

Reaction of an equimolar mixture of [VCl3L′] and [WO3L]·3H2O in MeOH–water (4 : 1) in the presence of air affords upon addition of NaClO4 blue [L′O(H2O)VIV(µ-O)WVIO2L]Cl(ClO4)1(L′= 1,4,7-trimethyl-1,4,7-triazacyclononane; L = 1,4,7-triazacyclononane). Crystals of 1 are monoclinic, space group P21/c, with a= 9.401(8), b= 20.61(1), c= 13.53(1)A, β= 102.47(7)°, and Z= 4. The complex is an asymmetric, heterodinuclear species consisting of vanadyl VOL′(OH2) and cis-LWVIO2 units which are asymmetrically bridged by an oxygen. A suspension of [MoIIIBr3L′] and excess of sodium penta-2,4-dionate(acac) in water reacts in the presence of air with formation of the asymmetric mixed-valence species [L′(acac)MoIII(µ-O)MoVIO2L′]2+. The bis(tetraphenylborate) salt 2 crystallizes in the monoclinic space group P21/a with a= 18.589(9), b= 18.30(1), c= 20.432(9)A, β= 104.73(4)° and Z= 4. The L′MoIII(acac) and cis-L′MoO2 units are linked by an asymmetric µ-oxo bridge with MoIII–Ooxo and MoVI–Ooxo distances of 2.034(4) and 1.808(4)A, respectively.