title: Non-oxo vanadium(IV) alkoxide chemistry: solid state structures, aggregation equilibria and thermochromic behaviour in solution.
abstract: The reversible thermochromic behaviour of homoleptic [{V(OR)(4)}(n)] complexes in solution [R = Pr(i) (product I), Bu(s) (B(s)), Nep (N) and Cy (C)] is accounted for the existence of an aggregation equilibrium involving dimeric and monomeric species in which vanadium(iv) is respectively five- and four-coordinate. Bulky R groups such as Bu(t) and Pe(t) (tert-pentoxide) prevent aggregation and therefore give rise to exclusively mononuclear compounds (B(t) and P(t), respectively) that are not thermochromic. The complexes and their temperature-dependent interconversion were characterised by single crystal X-ray diffractometry, magnetic susceptibility measurements and electronic, FTIR and EPR spectroscopies in a wide temperature range. Equilibrium constants and enthalpy and entropy changes for the dimerization reactions have been determined and compared with literature data.
authors.affiliation: Departamento de Química, Universidade Federal do Paraná, Centro Politécnico, 81530-900, Curitiba-PR, Brazil.
authors.forename: Kátia C M
authors.initials: KC
authors.lastname: Westrup
authors.forename: Thaiane
authors.initials: T
authors.lastname: Gregório
authors.forename: Danilo
authors.initials: D
authors.lastname: Stinghen
authors.forename: Dayane M
authors.initials: DM
authors.lastname: Reis
authors.forename: Peter B
authors.initials: PB
authors.lastname: Hitchcock
authors.forename: Ronny R
authors.initials: RR
authors.lastname: Ribeiro
authors.forename: Andersson
authors.initials: A
authors.lastname: Barison
authors.forename: Davi F
authors.initials: DF
authors.lastname: Back
authors.forename: Eduardo L
authors.initials: EL
authors.lastname: de Sá
authors.forename: Giovana G
authors.initials: GG
authors.lastname: Nunes
authors.forename: Jaísa F
authors.initials: JF
authors.lastname: Soares