Mono- and bimetallic manganese–carbonyl complexes and clusters bearing imidazol(in)ium-2-dithiocarboxylate ligands. Issue 6 (27th January 2017)

• Record Type: Journal Article
• Authors: Beltrán, Tomás F.; Zaragoza, Guillermo; Delaude, Lionel
• Is Part Of: Dalton transactions. Volume 46:Issue 6(2017)
• Page Start: 1779
• Page End: 1788
• Publication Date: 2017-01-27
• Subjects: Chemistry, Inorganic -- Periodicals; Chemistry, Physical and theoretical -- Periodicals; Chemistry, Inorganic -- Periodicals; 546.05
• DOI: 10.1039/c6dt04780g
• Languages: English
• ISSNs: 1477-9226

Abstract

Abstract : The coordination of NHC·CS2 zwitterions onto mono- and bimetallic manganese–carbonyl complexes and clusters was thoroughly investigated using a wide range of analytical techniques. Abstract : Five complexes with the generic formula fac -[MnBr(CO)3 (S2 C·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 (S2 C·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·CS2 ligands exhibited a bidentate κ 2 - 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  CO absorption bands on IR spectroscopy helped identify the presence of fac -Mn(CO)3 or Mn2 (CO)6 motifs, while the 13 C 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.