The complex trans-(PMe(3))(2)Pd(Ph)(NHPh)(1) reacts with the unsaturated electrophiles CO2, RNCO (R = Ph, (1)Bu, 2,6-(PrC6H3)-Pr-i), Ph(2)C=C=O and maleic anhydride. The less bulky substrates, CO2 and maleic anhydride, react by net insertion into the Pd-N bond, while the bulky electrophiles (1)BuNCO, (2,6-Pr-i-C6H3) NCO, and Ph(2)C=C=O react by N-H addition. N-15 labeling experiments show that the initial product of the reaction of phenylisocyanate with 1 is the Pd-N insertion product which then tautomerizes to the N-H addition product.