We report an easily prepared and bench-stable mononuclear Pd(0) source stabilized by a chelating N,N'-diaryldiazabutadiene ligand and maleic anhydride: DMP DAB-Pd-MAH. Phosphine ligands of all types, including bidentate phosphines and large cone angle biarylphosphines, rapidly and completely displace the diazabutadiene ligand at room temperature to give air-stable Pd(0) phosphine complexes. DMP DAB-Pd-MAH itself is readily soluble and stable in several organic solvents, making it an ideal Pd source for in situ catalyst preparation during reaction screening, as well as solution-dispensing to plate-based reaction arrays for high-throughput experimentation. Evaluation of DMP DAB-Pd-MAH alongside other common Pd(0) and Pd(II) sources in microscale reaction screens reveals that DMP DAB-Pd-MAH is superior at identifying hits across six different C-N, C-C, and C-O coupling reactions. DMP DAB-Pd-MAH, and the phosphine precatalysts derived therefrom, are also effective in preparative-scale cross couplings at low Pd loadings. ASSOCIATED CONTENTDetailed experimental procedures, full tables of screening data, characterization data, and XRD details. This material is available free of charge via the Internet at http://pubs.acs.org. CIFs for complexes 1, 3-5, 8 and 12 are deposited with the CCDC with deposition numbers 2056595-2056600.

Strong C–O bonds in pyrone and coumarin esters can undergo oxidative addition to Pd(0), with the reaction conditions and substrate structure controlling the outcome.

The effect of counteranion upon a cation's solution-phase reactivity depends on a subtle interplay of weak interactions.