Diphenylphosphino(phenyl pyridin-2-yl methylene)amine palladium(II) complexes: Chemoselective alkene hydrocarboxylation initiators

Dyer, Philip W.; Fawcett, John; Hanton, Martin J.

doi:10.1016/j.jorganchem.2005.04.032

Cited by 21 publications

(43 citation statements)

References 76 publications

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“…The molecular structure shows the rhodium atom to be in a square-planar geometry surrounded by the imino nitrogen atom trans to the carbonyl ligand and the chloro ligand trans to phosphorus. The geometrical parameters around the rhodium atom are comparable to those found in the analogous complexes [Rh(PyP)(CO)Cl] (PyP = 1-(2-diphenylphosphino)ethylpyrazole) [25], [Rh(P-N)(CO)Cl] (P-N = diphenylphosphino(phenyl pyridine-2-yl methylene)amine) [26] and [Rh(P-N*)(CO)Cl] (P-N* = (2S, 3S)-2-{4-(dimethylamino)benzylideneamino} + -3-methylpentyl bis (2,6-dimethylphenyl) phosphite) [27]. The formation of a six-membered chelate ring imposes distortion around the rhodium atom.…”

Section: Introductionsupporting

confidence: 69%

Rhodium(I) iminophosphine poly(propyleneimine) dendrimers: Synthesis, characterization and molecular structure of a mononuclear analogue

Antonels¹,

Therrien²,

Moss³

et al. 2009

Inorganic Chemistry Communications

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a b s t r a c tFirst (G1)-and second-generation (G2) poly(propyleneimine) (PPI) dendrimers were reacted with 2-(diphenylphosphino)benzaldehyde, to form iminophosphine-functionalised dendritic ligands (1, 2). The reaction of the dimeric precursor [RhCl(CO) 2 ] 2 with the heterobidentate dendritic ligands 1, 2 gave the corresponding rhodium(I) complexes (3, 4). There has been recent interest in the chemistry of polydentate ligands, especially those which combine ''soft" and ''hard" donor atoms [11]. The most used hemilabile ligands are the P,N-donor bidentate ligands, combining the distinct behaviour of a soft phosphorus atom which coordinates very strongly to a soft metal centre (e.g. palladium) and a hard nitrogen donor which is weakly bound. Non-rigid ligands, such as the widely studied iminophosphines, often act as chelating ligands that easily form five-or six-membered chelate rings. Iminophosphines display versatile coordination behaviour and are potentially hemilabile, making them useful for a variety of homogeneous processes, such as, C-C coupling reac- [16]. The steric and electronic properties of such ligands can also be fine-tuned and this can have a huge effect on the kinetics and thermodynamics of a chemical reaction [17].Examples of metallodendritic chelating heterobidentate complexes are rare. For metallodendrimers containing P and N donor atoms, many transition metals are coordinated in a P-monodentate or N-monodentate fashion. In this communication, we report on the synthesis of first-and second-generation chelating, heterobidentate [P, N] iminophosphine dendritic ligands and their coordination chemistry with a Rh(I) precursor. The molecular structure of a mononuclear analogue is also presented and discussed.The synthesis of the first-and second-generation iminophosphine-functionalised dendritic ligands 1 and 2 ( Fig. 1) [19] was achieved by a Schiff-base condensation reaction of the commercially available DAB-dendr-(NH 2 ) n with 2-diphenylphosphinobenzaldehyde. Screttas et al. first reported the synthesis of a third generation iminophosphine dendritic ligand based on a poly(propyleneimine) scaffold [18]. These dendritic P,N ligands were used in situ in the presence of palladium acetate in the Heck cross-coupling of p-anisyl bromide with styrene.The dendritic ligands (1, 2) were isolated as pale yellow solids in moderate yields (65-68%). These compounds were characterized by elemental analysis (C, H, N) Published in Inorganic Chemistry Communications 12, issue 8, 716-719, 2009 which should be used for any reference to this work 1imine moiety are observed as a triplet around 3.69 ppm, for 1 and 2. The appearance of a singlet at ca. 8.37 ppm, assigned to the imine proton (-CH 2 N@CH-CH 2 -) establishes that the condensation reaction has occurred. As was the case for Screttas and co-workers, it is important to consider syn and anti isomerism about the imine double bond [18]. One resonance is noted for the imine proton in both ligands, assigned to the trans isomer for steric reasons. The 31 P{ 1 H} ...

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Section: Introductionsupporting

confidence: 69%

Rhodium(I) iminophosphine poly(propyleneimine) dendrimers: Synthesis, characterization and molecular structure of a mononuclear analogue

Antonels¹,

Therrien²,

Moss³

et al. 2009

Inorganic Chemistry Communications

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“…[17] These data reflect ligand 1 c having undergone a one-electron reduction, behaving as an open-shell monoanion 1 cC À rather than as a neutral P,N ligand 1 c (Scheme 3). [35] Thus 2 is best described as possessing a Pd I À Pd I core bearing a reduced organic scaffold.…”

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confidence: 95%

“…[15,16] In contrast, the diphenyl analogue 1 b behaves only as a bidentate k 2 -PN Py ligand and exhibits no tautomerism. [17] Despite the importance of palladium catalysis in a variety of organic transformations, [17] there have been very few studies of Pd-NIL complexes. [13,19,20] This combination could help surmount the contradictory electronic and steric needs of the oxidative addition and reductive elimination steps key to many Pd-centered catalytic cycles through changes in NIL binding.…”

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confidence: 99%

“…[21] Compound 1 c was prepared by modification of a known procedure and, as for 1 b, was found to exist purely in the "open" form. [17,22] Access to the target Pd 0 complex was attempted through reaction of 1 c with equimolar quantities of [PdMe 2 (tmeda)] (tmeda = N,N,N',N'-tetramethylethylenediamine) using a variation on known methods. [23,24] The reaction proceeded to completion slowly over a Scheme 1.…”

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Exploiting Non‐Innocent Ligands to Prepare Masked Palladium(0) Complexes

et al. 2010

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“…Among such heteroditopic ligands, bidentate N,P chelates [2,3] are some of the most frequently used and have been shown to be beneficial in a number of applications such as allylic substitution, [4,5] olefin oligomerization, [6,7] and asymmetric hydrogenation. [9] While exploring the stereoelectronic properties of ligands I, it was of interest to probe the effect of replacing the aryl substituents of phosphorus by s-electron-withdrawing, pbasic amino groups. In combination with sources of Pd II , scaffold I (R = Ph) provides highly chemo-and regioselective initiators for direct alkene hydrocarboxylation in alcoholic media, which affords products that result from the coupling of two alkenes and two equivalents of carbon monoxide.…”

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A Truly Multifunctional Heterocycle: Iminophosphorane, N,P Chelate, and Dihydropyridine

et al. 2008

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Three in one: The anellated σ4‐1λ5‐[1,3,2]diazaphosphole 2 exists in tautomeric equilibrium with isomer 1 (see scheme) and undergoes three completely different types of reaction: trimethyl aluminum binds at the N terminus of the PN bond with ring retention, the dihydropyridine fragment reacts with an activated acetylene in a pseudo‐[2+2] cycloaddition, and PN bond cleavage is possible with RhI.

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Diphenylphosphino(phenyl pyridin-2-yl methylene)amine palladium(II) complexes: Chemoselective alkene hydrocarboxylation initiators

Cited by 21 publications

References 76 publications

Rhodium(I) iminophosphine poly(propyleneimine) dendrimers: Synthesis, characterization and molecular structure of a mononuclear analogue

Rhodium(I) iminophosphine poly(propyleneimine) dendrimers: Synthesis, characterization and molecular structure of a mononuclear analogue

Exploiting Non‐Innocent Ligands to Prepare Masked Palladium(0) Complexes

A Truly Multifunctional Heterocycle: Iminophosphorane, N,P Chelate, and Dihydropyridine

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