title: Syntheses and reactivity of 'sulfur rich' Re(iii) and Tc(iii) complexes containing trithioperoxybenzoate, dithiobenzoate and dithiocarbamate ligands.
abstract: Reduction-substitution reactions of [M(O)Cl(4)](-)(M=Re, (99)Tc) precursors with an excess of substituted dithiobenzoate ligands (R-PhCS(2))(-) in dichloromethane/methanol mixtures afford a series of six-coordinated neutral mixed-ligand complexes of the type M(III)(R-PhCS(3))(2)(R-PhCS(2))(M=Re; Rel--9; M=99)Tc; Tel--9). The coordination sphere is entirely filled by sulfur donor atoms, and the complexes adopt a distorted trigonal prismatic arrangement, as assessed by the X-ray crystal structure analysis of Re(4-Me-PhCS(3))(2)(4-Me-PhCS(2)), Re 2. These compounds show sharp proton and carbon NMR profiles, in agreement with the diamagnetism typical of low spin d(4) trigonal prismatic configurations. The red-ox processes involve reduction of the metal from Re(v) to Re(iii) and oxidation of dithiobenzoate to trithioperoxybenzoate. M2--9 complexes contain a substitution-inert [M(R-PhCS(3))(2)](+) moiety including the metal and two trithioperoxybenzoate fragments, while the third dithiobenzoate ligand is labile. The latter is efficiently replaced by reaction with better nucleophiles such as diethyldithiocarbamate giving a further class of mixed ligand complexes of the type M(III)(R-PhCS(3))(2)(Et(2)NCS(2))(M=Re; Re 10--18; M=(99)Tc; Tc--18), which retain the trigonal prismatic arrangement, as determined by the X-ray analyses of the representative compounds Re(PhCS(3))(2)(Et(2)NCS(2)), Re 10 and (99)Tc(PhCS(3))(2)(Et(2)NCS(2)), Tc 10.
authors.affiliation: Ecole Nationale Supérieure de Chimie de Rennes, UMR CNRS 6052, Synthèses et Activations de Biomolécules, Institut de Chimie de Rennes, Rennes, France. nicolas.noiret@ensc-rennes.fr
authors.forename: Nicolas
authors.initials: N
authors.lastname: Lepareur
authors.forename: Franck
authors.initials: F
authors.lastname: Mévellec
authors.forename: Nicolas
authors.initials: N
authors.lastname: Noiret
authors.forename: Fiorenzo
authors.initials: F
authors.lastname: Refosco
authors.forename: Francesco
authors.initials: F
authors.lastname: Tisato
authors.forename: Marina
authors.initials: M
authors.lastname: Porchia
authors.forename: Giuliano
authors.initials: G
authors.lastname: Bandoli