114157-65-2Relevant academic research and scientific papers
Complexes with functional phosphines. 12. Carbon-carbon coupling reactions by isocyanate insertion into nickel-, palladium-, and platinum-coordinated β-phosphino enolates. Molecular structures of [(C10H8N)Pd(Ph2PC{C(O)OEt}{=C(O)NHPh})] and cis-[Ni(Ph2PC{C(O)Ph}{=C(O)NH(p-MeC6H4)}) 2 ...
Bouaoud, Salah-Eddine,Braunstein, Pierre,Grandjean, Daniel,Matt, Dominique,Nobel, Dominique
, p. 2279 - 2286 (2008/10/08)
Full title: Complexes with functional phosphines. 12. Carbon-carbon coupling reactions by isocyanate insertion into nickel-, palladium-, and platinum-coordinated β-phosphino enolates. Molecular structures of [(C10H8N)Pd(Ph2PC{C(O)OEt}{=C(O)NHPh})] and cis-[Ni(Ph2PC{C(O)Ph}{=C(O)NH(p-MeC6H4)}) 2]·CH2Cl2. Phenyl isocyanate was reacted with [(C N)Pd{R2PCH=C(O)OEt}] (1, C N = o-C6H4CH2NMe2, R = Ph; 2, C N = C10H8N, R = Ph; 3, C N = o-C6H4CH2NMe2, R = c-C6H11) to afford the complexes [(C N)Pd(R2PC{C(O)OEt}{=C(O)NHPh})] (4-6), respectively, resulting from isocyanate insertion into the C-H bond of the enolate. Complex 5 has been characterized by a complete single-crystal X-ray diffraction study: triclinic, space group P1 with Z = 2, a = 9.276 (2) A?, b = 12.290 (7) A?, c = 14.336 (8) A?, α = 70.38 (3)°, β = 86.70 (2)°, γ = 69.18 (2)°, V = 1435.6 A?3, and ρ(calcd) = 1.478 g cm-3. The structure has been refined for the 2676 reflections with I > 3σ(I) to R = 0.037 and Rw = 0.045. In this molecule the polyfunctional phosphine is P,O-(amide)-bonded to the metal center, and the NH proton is in strong interaction with the conjugated ester group. With the exception of the P-bonded aryl groups, this molecule displays a high degree of planarity. When phenyl isocyanate was reacted with the related ketonates [(C N)Pd{Ph2PCH=C(O)Ph}] (7, C N = o-C6H4CH2NMe2; 8, C N = C10H8N), two C-C coupling products were formed, namely [(C N)Pd(Ph2PC{=C(O)Ph}{C(O)NHPh})] (9a and 10a, respectively) and [(C N)Pd(Ph2PC{C(O)Ph}{=C-(O)NHPh})] (9b and 10b, respectively). These are present in a ca. 1:1 ratio and were shown to be in equilibrium. An exchange mechanism between the a and b forms is proposed. A comparison is made between the carbon-carbon coupling reactions involving complexes 1-3, 7, and 8 and the heterocumulenes ArNCO and CO2. The ArNCO coupling reaction also occurred when the β-phosphino ketonate was coordinated to other metals. With cis-[Ni{Ph2PCH=C(O)Ph}2] (11), the complexes cis-[Ni-(Ph2PC{C(O)Ph}{=C(O)NH(Ar)})2] (12, Ar = Ph; 13, Ar = p-MeC6H4) were formed as a result of isocyanate insertion into each PC-H bond. The molecular structure of 13·CH2Cl2 has been determined by X-ray diffraction: triclinic, space group P1 with Z = 2, a = 14.363 (4) A?, b = 14.602 (12) A?, c = 14.324 (4) A?, α = 112.23 (4)°, β = 109.56 (2)°, γ = 99.19 (4)°, V = 2475.4 A?3, and ρ(calcd) = 1.364 g cm-3. The structure has been refined for the 3325 reflections with I > 4.5σ(7) to R = 0.042 and Rw = 0.053. The coordination around the Ni atom is approximately square planar, with Ni-P and Ni-O bond lengths of respectively 2.170 (3) A? (average) and 1.877 (4) A? (average). Whereas each of the N-bonded aryl groups is conjugated with the planar diketonate system, the phenyl groups attached to the keto groups are almost perpendicular to the metal coordination plane in order to minimize repulsions with the neighboring PPh2 groups. The reaction of phenyl isocyanate with cis-[Pt{Ph2PCH=C(O)Ph}2] gave the monoinsertion product [Pt{Ph2PCH=C(O)Ph}(Ph2PC{C(O)Ph}{=C(OH)NPh})] (15), in which a third bonding mode (P,N) of this class of functional phosphines was found. All complexes were characterized by elemental analyses and IR, 1H NMR, and 31P{1H} NMR spectroscopy.
