The first example of the addition of an ambident nucleophile's endocyclic center to a coordinated isocyanide is reported, namely, the Pd-II- and Pt-II-mediated reaction of aryl isocyanides with N-methylimidazole- and N-methyltriazole-2-thiones resulting in C,S-chelated deprotonated diaminocarbene complexes. The obtained complexes were isolated in good yields (88-95%) and characterized by elemental analysis (C, H, N), high-resolution mass spectrometry, and IR, 1D (H-1, C-13, Pt-195) and 2D (H-1-H-1 COSY, H-1-H-1 NOESY, H-1-C-13 HSQC, H-1-C-13 HMBC) NMR spectroscopies, as well as by single-crystal X-ray diffraction for the four complexes. The favorability of the resulting regioselectivity was confirmed by DFT calculations.