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

Abstract

The dialkylcyanamide complexes Q[PtCl3(NCNR2)] (Q = Ph3PCH2Ph, R2 = Me21, Et22, C5H103, C4H8O 4; Q = NMe4, R2 = Me25; Q = NEt4, R2 = Me26) were synthesized either by dissolving Q2[Pt2(μ-Cl)2Cl4] 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, R2 = Me2, 7; Et2, 8; C5H10, 9; C4H8O, 10; Q = Me4N, R2 = Me211; Q = Et4N, R2 = Me2, 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 (1)H and (13)C{(1)H} NMR spectroscopy. The structure of 1 was additionally verified by a single-crystal X-ray diffraction.

Highly Reactive NiII‐Bound Nitrile–Oxime Coupling Intermediates Stabilized by Substituting Conventional Nitriles with a Dialkylcyanamide

“…Despite the wealth of chemistry associated with the nucleophilic addition of the oxime HON=C functionality to the so‐called conventional nitrile NCR (R = alkyl, aryl) ligands, only a few works14,17 have explored metal‐bound dialkylcyanamides – NCNAlk 2 – as substrates for the addition. These reports indicate substantial distinctions in the reaction rates and the nature of products formed, [2e,3a,3b,14,17e–17g,18] and it means that these variances were recognized not only at the quantitative,3b,17f but also at the qualitative level when dialkylcyanamides and conventional nitrile ligands react with the same reagent in absolutely different ways giving, consequently, different products. [3a,3b,17f,17g,18]…”

“…It was recognized earlier that in many instances ligated Alk 2 NCN compounds exhibit different behavior from the coordinated conventional nitriles RCN. These differences were recognized not only at the quantitative,17f,30 but also at the qualitative level2e,3a,3b,3e when conventional nitrile and dialkylcyanamide ligands react with the same reagent in different ways to give, consequently, different products. The distinctions in the reaction routes are accounted for by a special role of the NR 2 group in dialkylcyanamides.…”

Platinum(II)‐Mediated Double Coupling of 2,3‐Diphenylmaleimidine with Nitrile Functionalities To Give Annulated Pentaazanonatetraenate (PANT) Systems

“…When the reaction between the corresponding complexes 6-9 and Imd (molar ratio 1:2.5, CH 2 Cl 2 , r.t.) proceed for 14 h, no changes in the yields of 15-18 were observed. It is noteworthy that, as expected, [46] dialkylcyanamide systems are more reactive toward nucleophilic addition than those based on the conventional nitrile species.…”

Novel (cyanamide)ZnIIcomplexes and zinc(ii)-mediated hydration of the cyanamide ligands

“…1,3,8 In contrast, the chemistry of cyanamides NCNR 2 (R = alkyl, aryl) is incomparably less investi-gated, although some studies on their coordination chemistry prove that NCNR 2 ligands exhibit excitingly different behavior at the quantitative-and at the qualitative levels as compared to the conventional nitriles NCR (R = alkyl, aryl). [12][13][14][15][16][17][18][19][20] In recent work, we studied the reactivity of nitrile and cyanamide ligands at platinum(II and IV) and palladium(II) centers and observed significant differences in reaction rates and also in the nature of products derived from metal-mediated conversion of dialkylcyanamide and conventional nitrile ligands. [12][13][14][15][16][17][18][19][20] In the current work, we have focused our attention on cyanamide metal systems bearing a much more kinetically labile metal center than platinum or palladium, viz.…”

“…[12][13][14][15][16][17][18][19][20] In recent work, we studied the reactivity of nitrile and cyanamide ligands at platinum(II and IV) and palladium(II) centers and observed significant differences in reaction rates and also in the nature of products derived from metal-mediated conversion of dialkylcyanamide and conventional nitrile ligands. [12][13][14][15][16][17][18][19][20] In the current work, we have focused our attention on cyanamide metal systems bearing a much more kinetically labile metal center than platinum or palladium, viz. zinc(II).…”