Carbon-Carbon Bond Activation at Chromium(I): An 11-Electron Complex Cleaving Dialkynes

An 11-electron T-shaped chromium(I) complex was obtained by reduction of a PNP-supported chromium(II) iodide complex. Its d⁵ high-spin electronic structure was characterized employing paramagnetic NMR, EPR, UV/Vis and magnetic measurements (SQUID). The complex readily reacts with conjugated dialkynes to cleave the internal C-C bond, forming the respective acetylide complexes. Varying the alkyne substituents enabled the isolation and characterization of dinuclear dialkynedichromium intermediates which thermally convert to the products.