Dialkylcyanamides are more reactive substrates toward metal-mediated nucleophilic addition than alkylcyanides

The dialkylcyanamide complexes Q[PtCl3(NCNR2)] (Q = Ph3PCH2Ph, R-2 = Me-2 1, Et-2 2, C5H10 3, C4H8O 4; Q = NMe4, R-2 = Me-2 5; Q = NEt4, R-2 = Me-2 6) were synthesized either by dissolving Q(2)[Pt-2(mu-Cl)(2)Cl-4] in neat NCNR2 (1-4) or by substitution of a NCNR2 ligand with Cl- in [PtCl2(NCNR2)(2)] by its treatment with QCl (5, 6). Nucleophilic addition of dibenzylhydroxylamine, HON(CH2Ph)(2), to 1-6 results in the formation of the complexes Q[PtCl3{NHC(NR2)ON(CH2Ph)(2)}] (Q = Ph3PCH2Ph, R-2 = Me-2, 7; Et-2, 8; C5H10, 9; C4H8O, 10; Q = Me4N, R-2 = Me-2 11; Q = Et4N, R-2 = Me-2, 12) that further convert at room temperature in the solid state (1-24 h) or in a solution (0.5-2 h) to the imine complexes Q[PtCl3{N(CH2Ph)=C(H) Ph}] (Q = Ph3PCH2Ph, 13; Me4N, 14; Et4N, 15) and the corresponding dialkylureas H2NC(=O)NR2. The competitive reactivity study of the nucleophilic addition of HON(CH2Ph)(2) to (Ph3PCH2Ph)[PtCl3(NCR')] (R' = Ph, NR2, CH2Ph) indicated that the reactivity of the coordinated NCNR2 is comparable to NCPh, while NCCH2Ph appeared to be much less reactive than the former two ligands. Compounds 1-6 and 13 were fully characterized by elemental analyses (C, H, N), high resolution ESI-MS, IR, and H-1 and C-13{H-1} NMR spectroscopy. The structure of 1 was additionally verified by a single-crystal X-ray diffraction.