AbstractWe describe the results of a study on the stabilities of pincer‐type nickel complexes relevant to catalytic hydroalkoxylation and hydroamination of olefins, CC and CX couplings, and fluorination of alkyl halides. Complexes [(POCsp3OP)NiX] are stable for X=OSiMe3, OMes (Mes=1,3,5‐Me3C6H2), NPh2, and CCH, whereas the O(tBu) and N(SiMe3)2 derivatives decompose readily. The phenylacetylide derivative transforms gradually into the zero‐valent species cis‐[{κP,κC,κC′‐(iPr2POCH2CHCH2)}Ni{η2,κC,κC′‐(iPr2P(O)CCPh)}]. Likewise, attempts to prepare [(POCsp3OP)NiF] gave instead the zwitterionic trinuclear species [{(η3‐allyl)Ni}2‐{μ,κP,κO‐(iPr2PO)4Ni}]. Characterization of these two complexes provides concrete examples of decomposition processes that can dismantle POCsp3OP‐type pincer ligands by facile CO bond rupture. These results serve as a cautionary tale for the inherent structural fragility of pincer systems bearing phosphinite donor moieties, and provide guidelines on how to design more robust analogues.