Gas‐phase C―C coupling reactions mediated by Ni (II) complexes were studied using a linear quadrupole ion trap mass spectrometer. Ternary nickel cationic carboxylate complexes, [(phen)Ni (OOCR
1)]
+ (where phen = 1,10‐phenanthroline), were formed by electrospray ionization. Upon collision‐induced dissociation (CID), they extrude CO
2 forming the organometallic cation [(phen)Ni(R
1)]
+, which undergoes gas‐phase ion‐molecule reactions (IMR) with acetate esters CH
3COOR
2 to yield the acetate complex [(phen)Ni (OOCCH
3)]
+ and a C―C coupling product R
1‐R
2. These Ni(II)/phenanthroline‐mediated coupling reactions can be performed with a variety of carbon substituents R
1 and R
2 (
sp3,
sp2, or aromatic), some of them functionalized. Reaction rates do not seem to be strongly dependent on the nature of the substituents, as
sp3‐
sp3 or
sp2‐
sp2 coupling reactions proceed rapidly. Experimental results are supported by density functional theory calculations, which provide insights into the energetics associated with the C―C bond coupling step.
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