The reaction of manganese carbonyl with tert-butylisocyanide: Synthesis and characterization of cis- and trans-[MnI(tBuNC)4(CN)(CO)]

The reaction of Mn2(CO)10 with tert-butyl isocyanide in the presence of 10 bar of carbon monoxide leads to the formation of cis- and trans-[Mn(tBuNC)4(CN)(CO)], 1a and 1b, in good yields together with [Mn(tBuNC)6]CN (2), as a minor product. Nevertheless, the reaction pathway highly depends on the reaction conditions. An interesting side-product is obtained, if chloroform is used during the workup procedure. Compound 3 is composed of cationic [Mn(tBuNC)5(CO)] units as well as dinuclear anionic [Mn(tBuNC)4(CO)(μ–CN)MnCl3] moieties. If no additional CO pressure is applied to the system, the organic product N,N′-di-tert-butyl-3,5-bis-tert-butylimino-4-phenyl-cyclopent-1-ene-1,2-diamine (4), is formed in considerable amount. Compound 4 most probably is produced via a double benzylic C–H activation of the solvent toluene and the oligomerization of four isocyanide moieties. The reaction of 1b with Co(NO3)2 leads to the isolation of the trinuclear cyanide bridged coordination compound {[Mn(tBuNC)4) (CO) (μ–CN)]2Co(NO3)2}, 5, in which the cobalt atoms are tetrahedrally surrounded by the two cyanide ligands and the η1-coordinated nitro groups. In contrast to the reaction of 1b, treatment of the dicyano complexes cis- or trans-[Ru(tBuNC)4(CN)2] with Co(NO3)2 results in the formation of the coordination polymers {[Ru(tBuNC)4(CN)2]Co(NO3)2}n, 7 (trans) and 9 (cis). All new compounds are characterized by X-ray diffraction experiments.

The reaction of Mn2(CO)10 with tert-butyl isocyanide proceeds either via the oxidation of manganese together with the concomitant reductive cleavage of isocyanides producing the coordination compounds cis- and trans-[Mn(tBuNC)4(CN)(CO)] (1a and 1b), or via the oligomerization of isocyanides yielding the cyclopentene 2. Additional side-products as well as coordination oligomers based on 1b are also reported.Figure optionsDownload as PowerPoint slide