UNUSUAL SOLID-STATE REACTION OF [(CRL(ACAC))2(MU-H3O2)][PF6]3 - ISOLATION AND CRYSTAL-STRUCTURES OF [CRL(ACAC)F]PF6 AND [CRL(ACAC)(O2PF2)]PF6 (L = 1,4,7-TRIMETHYL-1,4,7-TRIAZACYCLONONANE, ACAC = PENTANE-2,4-DIONATE)

From a concentrated aqueous solution of the mononuclear complexes [CrL(acac)(OH)]PF6.H2O and [CrL(acac)(OH2)][ClO4]2 at pH almost-equal-to 6 the dinuclear H3O2--bridged species [{CrL(acac)}2(mu-H3O)][PF6]3 was isolated as a crystalline red solid (L = 1,4,7-trimethyl-1,4,7-triazacyclononane, acac = pentane-2,4-dionate). The dinuclear complex reacted at 145-degrees-C in the solid state with evolution of 3 equivalents of HF, yielding quantitatively the mononuclear complexes [CrL(acac)F]PF6 and [CrL(acac)(O2PF2)]PF6 in equal amounts. Thus an unco-ordinated PF6- anion is thermally converted into a co-ordinated fluoride and a monodentate O2PF2- ligand. The crystal structures of [CrL(acac)(OH2)]-[ClO4]2, [CrL(acac)F]PF6 and [CrL(acac)(OPF2)]PF6 have been determined by X-ray crystallography. The cobalt(III) complex [{CoL(acac)}2(mu-H3O2)][PF6]3 has also been prepared and structurally characterized. It is isostructural with the chromium analogue. Heating to its melting point at 190-degrees-C did not induce solid-state transformation to mononuclear cobalt(III) species analogous to [CrL(acac)F]PF6 and [CrL(acac)(O2PF2)]PF6.