Utilization of Redox and Acid/Base Chemistry for the Deprotection of a Mn(dmpe)2(C⋮CSiMe3)2 Complex

• Published in: Organometallics 2001-07, Vol.20 (14), p.3122-3131
• Main Authors: Fernández, Francisco J, Alfonso, Montserrat, Schmalle, Helmut W, Berke, Heinz
• Format: Article
• Language: English
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om010172k

The reaction of the low-spin d5 complex Mn(dmpe)2(C⋮CSiMe3)2 (1) (dmpe = 1,2-bis(dimethylphosphino)ethane) with [NBu4][Ph3F2M] (M = Si or Sn) yields the SiMe3 metathesis products Mn(dmpe)2(C⋮CMPh3)2 (M = Si 2a, Sn 2b). When the Mn(II) species 1 was dissolved in MeOH in the presence of NaBF4, disproportionation occurred with formation of the Mn(I) products Mn(dmpe)2(C⋮CSiMe3)(CCH2) (3a) and [Mn(dmpe)2(C⋮CSiMe3)(⋮C−CH3)][BF4] (5a) and the cationic Mn(III) complex [Mn(dmpe)2(C⋮CSiMe3)2][BF6] (4a). In a similar way 1 was transformed into [Mn(dmpe)2(C⋮CSiMe3)2][H2F3] (4b) and [Mn(dmpe)2(C⋮CSiMe3)(⋮C−CH3)][H2F3] (5b) by its reaction with excess of HF·pyridine. The reaction of 1 with Li or Na in toluene at 100 °C gave the new d6 cis-bisalkynyl complexes [Mn(dmpe)2(C⋮CSiMe3)2][M] (M = Li 6a, Na 6b). The trans-alkynylvinylidene derivatives Mn(dmpe)2(C⋮CSiMe3)(CC(E)SiMe3) (E = H 3b, SnMe3 3c) were obtained by the reaction of species 6 with stoichiometric MeOH or ClSnMe3. In MeOH/KOH solutions complex 3b or 3c was converted into the trans-alkynylvinylidene species 3a. The reaction of complex 3a with HBF4 or HF·pyridine produced the carbyne complexes [Mn(dmpe)2(C⋮CSiMe3)(⋮C−CH3)][A] (A = BF4 5a, H2F3 5b). These new compounds have been characterized by NMR and IR spectroscopy and elemental analyses, and for 2a, 2b, 3a, 4b, and 6b X-ray diffraction studies have been performed.