Study of the Reactivity of 2-Acetyl-, 2-Cyano-, 2-Formyl-, and 2-Vinylphenyl Palladium(II) Complexes. Mono- and Triinsertion of an Isocyanide into the Pd−C Bond. A 2-Cyanophenyl Palladium Complex as a Ligand

Abstract

We have studied the reactivity of the complexes [Pd(C6H4X-2)Br(bpy)] (bpy = 2,2‘-bipyridine; X = C(O)Me (1a), CN (1b), CHO (1c)), [Pd{C6H4CHCH2-2}(PPh3)(bpy)](TfO) (TfO = CF3SO3; 2d), trans-[Pd(C6H4X-2)Br(PPh3)2] (X = C(O)Me (3a), CN (3b), CHCH2 (3d)), and [Pd(μ-Br)(C6H4X-2)(PPh3)]2(X = C(O)Me (4a), CN (4b)). Their reactions with XyNC (Xy = 2,6-dimethylphenyl) depend on the nature of X and the other ligands and on the reaction conditions. The products of these reactions are mono- and triinserted complexes. Among the former are [Pd{C(NXy)C6H4X-2}Br(L2)] (L2 = bpy, X = C(O)Me (5a), CN (5b); L = CNXy, X = C(O)Me (6a), CN (6b), CHCH2 (6d)) and trans-[Pd{C(NXy)C6H4CHCH2-2}(CNXy)2(PPh3)](TfO) (7d). The reaction of 1c with XyNC (1:5 molar ratio) gives 10, a product resulting after substitution of bpy, coordination of two molecules of XyNC, triinsertion of XyNC, and a cyclization resulting after the attack of the nitrogen of the first inserted molecule at the carbon atom of the formyl group. The complexes [Pd{κ2 C 1,N 3-C(NXy)C(NXy)C(NXy)C6H4X-2}Br(CNXy)] (X = C(O)Me (8a), CN (8b)) were obtained by reacting (i) 3a or 3b with XyNC (1:4 molar ratio) or (ii) Pd(dba)2 (dba = dibenzylideneacetone) with BrC6H4X-2 and XyNC (1:1:4 molar ratio). When this oxidative addition reaction was carried out with BrC6H4CHO-2, the resulting product decomposed to give the Pd(I) complex [Pd2Br2(CNXy)4] (9). Tl(TfO) was reacted with (i) 8a and 8b (1:1 molar ratio) to give the corresponding triflato complexes 11a and 11b, (ii) 4a (1:2 molar ratio) in the presence of moisture to give the cyclopalladated aquo complex [Pd{κ2 C,O-C6H4{C(O)Me-2}(OH2)(PPh3)](TfO) (12a), and (iii) 4b (3:1 molar ratio) to give [Pd(C6H4CN-2)(κ2 N,N- 4b)(PPh3)](TfO) (13b), in which 4b behaves as a ligand through the two cyano groups. The crystal structures of 5b, 6b, 7d, 8a,b, 9, 10, 11a,b, 12a, and 13b have been determined by X-ray diffraction studies.

Synthesis and reactivity of thiophene palladium and thiophene dipalladium complexes with unsaturated molecules

“…These complexes, 8 and 11, were confirmed by physical tools (IR, NMR, elemental analysis), which were consistent with the result described by Vicente et al 52 for the triand tetra-insertion of an isocyanide XyNC (Xy = 2,6-dimethylphenyl) into the Pd-C bond of the ortho-substituted phenylpalladium complexes. There is no precedent for this type of ring structure, until confirmed by an X-ray structure analysis.…”

“…There is no precedent for this type of ring structure, until confirmed by an X-ray structure analysis. 52 …”

Chiral Platinum(II) Compounds Containing Ferrocenyl Schiff Bases Acting as (N), (N,O)–, [C(sp2,ferrocene),N]– or [C(sp2,ferrocene),N,O]2– Ligands

“…31 P{ 1 H} and 195 Pt{ 1 H} NMR spectroscopic data [27] for 12-13 were consistent with those reported for other platinacycles containing a cyclometallated Schiff base, [24b,24c,43] in which the phosphane and the metallated carbon are in a cis arrangement, in good agreement with the transphobia effect. [44] In summary, the results presented have allowed us to establish the best experimental conditions to selectively con- The studies undertaken also showed the outstanding reactivity of compounds 2 and their utility for the preparation of a wide variety of chiral platinum(II) complexes by: a) activation of the σ(O-H) to give 4 {which may be transformed into 5 by the subsequent isomerisation anti-(E) Ǟ syn-(Z) of the coordinated Schiff base, Scheme 1, steps (B) and (C)} or b) the cycloplatination of the ferrocenyl unit {Scheme 2, step (A)} to give the diastereomers 8 and 9. In the presence of NaOH, 8 (or 9) evolve to the chiral derivatives 10 (or 11) with a [C(sp 2 ,ferrocene),N,O] 2-ligand {Scheme 2, steps (C) and (D)}.…”

Synthesis, Structure, Reactivity, and Catalytic Activity of C,N‐ and C,N,N‐Orthopalladated Iminophosphoranes

“…The cis arrangement of the metallated carbon and the phosphane ligand is in good agreement with the transphobia between these ligands. [37,[55][56][57] However, the NMR spectra of complex 4 show the presence of a mixture of isomers a and b (see Scheme 1) in a molar ratio 4a:4b of 4.1:1. This fact is worthy of note, since the typical reactivity of C,N-cyclopalladated halide-bridged dimers towards neutral ligands L (L = phosphanes, pyridines, etc.)…”