title: Mono- and bimetallic manganese-carbonyl complexes and clusters bearing imidazol(in)ium-2-dithiocarboxylate ligands.
abstract: Five complexes with the generic formula fac-[MnBr(CO)3(S2C·NHC)] were obtained by reacting [MnBr(CO)5] with a set of representative imidazol(in)ium-2-dithiocarboxylate zwitterions. These ligands are the adducts of N-heterocyclic carbenes (NHCs) and carbon disulfide. The mononuclear Mn(i) derivatives were coupled with Na[Mn(CO)5] to afford bimetallic [Mn2(CO)6(S2C·NHC)] clusters. Yet, the most convenient strategy to access these dinuclear Mn(0) products implied a direct carbonyl substitution from the [Mn2(CO)10] dimer. The molecular structures of three monometallic and four bimetallic compounds were elucidated by single crystal X-ray diffraction analysis. In the monometallic complexes, the NHC·CS2ligands exhibited a bidentate κ2-S,S' coordination mode with an S-C-S bite angle of about 116°. In the dinuclear clusters, the CS2-unit acted as a chelate toward one manganese center and as a pseudoallylic ligand toward the other one. The S-C-S bite angle was reduced to ca. 104°. Thus, the zwitterions displayed a remarkable flexibility, which also permitted a staggered arrangement of the carbonyl groups in the bimetallic systems. Examination of the [small nu, Greek, macron]COabsorption bands on IR spectroscopy helped identify the presence of fac-Mn(CO)3or Mn2(CO)6motifs, while the13C NMR chemical shift of the CS2-moiety was a reliable indicator for monitoring its hapticity. Whereas the dinuclear clusters were air- and moisture-stable crystalline solids, mononuclear halido derivatives displayed only a limited stability under aerobic conditions. Both types of compounds underwent rather unselective, extensive fragmentations in the gas phase, in sharp contrast with the analogous rhenium derivatives that led to clean sequential decarbonylation processes upon collision-induced dissociation.
authors.affiliation: Laboratory of Organometallic Chemistry and Homogeneous Catalysis, Institut de Chimie (B6a), Allée du six Août 13, Quartier Agora, Université de Liège, 4000 Liège, Belgium. l.delaude@ulg.ac.be.
authors.forename: Tomás F
authors.initials: TF
authors.lastname: Beltrán
authors.affiliation: Unidade de Difracción de Raios X, Edificio CACTUS, Universidade de Santiago de Compostela, Campus Vida, 15782 Santiago de Compostela, Spain.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Zaragoza
authors.affiliation: Laboratory of Organometallic Chemistry and Homogeneous Catalysis, Institut de Chimie (B6a), Allée du six Août 13, Quartier Agora, Université de Liège, 4000 Liège, Belgium. l.delaude@ulg.ac.be.
authors.forename: Lionel
authors.identifier: http://orcid.org/0000-0002-1134-2992
authors.initials: L
authors.lastname: Delaude