CN and NO Bond Cleavages of Acetonitrile and Nitrosyl Ligands at a Dimolybdenum Center to Render Ethylidyne and Acetamidinate Ligands

Extended reduction of [Mo2Cp2(μ-Cl)(μ-PtBu2)(NO)2] (1) with Na(Hg) in acetonitrile (MeCN) at room temperature resulted
in an unprecedented full cleavage of the CN bond of a coordinated
MeCN molecule to yield the vinylidene derivative Na[Mo2Cp2(μ-PtBu2)(μ-CCH2)(NO)2], which upon protonation
with (NH4)PF6 gave the ethylidyne complex [Mo2Cp2(μ-PtBu2)(μ-CMe)(NO)2] [Mo1–Mo2 = 2.9218(2)
Å] in a selective and reversible way. Controlled reduction of 1 at 273 K yielded instead, after protonation, the 30-electron
acetamidinate complex [Mo2Cp2(μ-PtBu2)(μ-κN:κN′-HNCMeNH)(μ-NO)]PF6 [Mo1–Mo2 = 2.603(2) Å], in a process thought to stem
from the paramagnetic MeCN-bridged intermediate [Mo2Cp2(μ-PtBu2)(μ-NCMe)(NO)2], followed by a complex sequence of elementary steps including
cleavage of the NO bond of a nitrosyl ligand.