Binding and Activation of Small Molecules by Three-Coordinate Cr(I)

[( i -Pr 2 Ph) 2 nacnacCr] 2 (μ-η 2:η 2 -N 2 ) ( 2 ) has been prepared and structurally characterized; it contains a bridging side-on bonded dinitrogen ligand with a N−N distance of 1.249(5) Å. Reactions of this reactive Cr(I) synthon with various small molecules resulted in a series of unusual molecules and transformations; thus CO yielded the binuclear isocarbonyl [( i -Pr 2 Ph) 2 nacnacCr] 2 (CO)(μ-η 1:η 1 -CO) 2, ethylene gave [( i -Pr 2 Ph) 2 nacnacCr] 2 (μ-η 2:η 2 -C 2 H 4 ), O 2 oxidatively added to produce ( i -Pr 2 Ph) 2 nacnacCr(O) 2, and azobenzene afforded the product of N N bond cleavage [( i -Pr 2 Ph) 2 nacnacCr] 2 (μ-NPh) 2 . 2 can be prepared in good yield and affords a facile entry to low-coordinate Cr(I) coordination chemistry.