o-(Diphenylphosphino)benzaldehyde: a versatile ligand and a useful hemilabile ligand precursor

Garralda, María A.

doi:10.1016/j.crci.2005.03.009

Cited by 23 publications

(39 citation statements)

References 66 publications

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“…Brown crystals suitable for X-ray diffraction were obtained by slow evaporation of the CH 2 Cl 2 solution. 1 (3). A solution of 1 (200 mg, 0.25 mmol) in 150 mL of a THF/CH 2 Cl 2 mixture (4/1) was added to PMe 3 (3 mL, 29 mmol), and the mixture was stirred for 3 days.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Cooperative Metal–Ligand Reactivity and Catalysis in Low-Spin Ferrous Alkoxides

2015

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This report describes examples of combined Fe-and O-centered reactivity of Fe(P 2 O 2 )(CO) 2 (1), where P 2 O 2 is the diphosphinoglycolate (Ph 2 PC 6 H 4 CHO) 2 2−. This 18e low-spin ferrous dialkoxide undergoes substitution of CO to give the labile monosubstituted derivatives Fe(P 2 O 2 )(CO)-(L) (L = PMe 3 , pyridine, MeCN). Treatment of Fe(P 2 O 2 )-(CO) 2 with Brønsted acids results in stepwise O-protonation, affording rare examples of low-spin Fe(II) complexes containing alcohol ligands. Substitution reactions with amides (RC(O)NH 2 ) proceeds with binding of the carbonyl and formation of an intramolecular hydrogen bond between NH and the neighboring alkoxo ligand. This two-site binding was confirmed with crystallographic characterization of the thiourea-substituted derivative. Fe(P 2 O 2 )(CO) 2 reacts with Ph 2 SiH 2 to give the O-silylated hydrido complex, which is inactive for hydrosilylation. The monocarbonyl derivatives Fe(P 2 O 2 )(CO)(L) (L = NCMe, PMe 3 , acetamide) are precursors to catalysts for the hydrosilylation of benzaldehyde, acetophenone, and styrene. ■ INTRODUCTIONMonomeric alkoxoiron(II) complexes are rare. 1 The oxygen centers in such complexes are expected to be highly basic owing to electrostatic interactions between the metal and ligand, although the Fe−O bonds themselves remain strong. 2 The enhanced basicity of the alkoxide ligand in such complexes usually results in multinuclear complexes with bridging alkoxo ligands. For these reasons, studies on the reactivity of ferrous alkoxides are few.We recently described a one-pot synthesis of an iron(II) diphosphine-dialkoxide dicarbonyl complex Fe(P 2 O 2 )(CO) 2 (1; P 2 O 2 = (Ph 2 PC 6 H 4 CHO) 2 2− ). This complex arises by the coupling of 2 equiv of 2-diphenylphosphinobenzaldehyde (PCHO) 3 in the presence of iron(0) carbonyl reagents (eq 1; bda = benzylideneacetone). 4 Similar condensations had been observed using PCHO with low-valent tungsten and technetium. 5 Our iron system is attractive because the conversion is highly efficient and the reagents are inexpensive. As a dialkoxo iron(II) carbonyl, 1 is unique. In the previous report, 1 was shown to form stable adducts with a variety of Lewis acids, including BF 3 , which bind to the alkoxide sites. In this paper, we provide new perspectives on the O-centered reactivity of 1. These results demonstrate the high basicity of alkoxo ligands and an unprecedented activation mode of Si−H bonds by alkoxo-iron functionalities to afford a series of new hydrido-iron complexes. We also found that the diphosphino-dialkoxo iron species with labile ligands (e.g., MeCN, MeC(O)NH 2 ) are active catalysts for the hydrosilylation of aldehydes, ketones, and even alkenes. The spectroscopic features of all newly synthesized compounds are summarized in Table 1. ■ RESULTS Substitution of Fe(P 2 O 2 )(CO) 2 by Lewis Bases. The CO ligands of 1 are labile. In CH 2 Cl 2 solutions, 1 exchanges with 1 atm of 13 CO over the course of several hours (see the Supporting Information). The lability of the CO ligands ...

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Section: ■ Experimental Sectionmentioning

confidence: 99%

Cooperative Metal–Ligand Reactivity and Catalysis in Low-Spin Ferrous Alkoxides

2015

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“…The non‐acetal‐protected analogue 2‐(diphenylphosphanyl)benzaldehyde ( L2 ) can coordinate in the same way, as has been observed for Pd, Ru and Rh,15 but for platinum only P coordination has been observed to date 16,17. Additionally, after κ P coordination of L2 , an oxidative C–H addition (i.e., a cyclometallation) may occur to yield organometallic inner complexes with the ligand κ P ,κ C ‐coordinated 18. Examples are the formation of [Pt{PPh 2 ( o ‐C 6 H 4 CO)‐κ P ,κ C } 2 ] and [PtH(PPh 3 ){PPh 2 ( o ‐C 6 H 4 CO)‐κ P ,κ C }] 19…”

Section: Introductionmentioning

confidence: 99%

On the Reactivity of Platina‐β‐diketone and Acetylplatinum(II) Complexes toward 2‐(Diphenylphosphanyl)benzaldehyde and Its Dioxolane Derivative

et al. 2013

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The dinuclear platina‐β‐diketone [Pt2{(COMe)2H}2(μ‐Cl)2] (1) reacts with four and two equivalents of 2‐[2‐(diphenylphosphanyl)phenyl]‐1,3‐dioxolane (L1) to yield [Pt(COMe)Cl(PPh2{o‐C6H4CH(O2C2H4)}‐κP)2] (3) and [Pt(COMe)Cl(PPh2{o‐C6H4CH(O2C2H4)}‐κP,κO)] (4), respectively. The weak Pt–O bond in 4 can be easily broken up by stronger donors. Thus, complex 4 reacts with PPh3 to yield [Pt(COMe)Cl(PPh3)(PPh2{o‐C6H4CH(O2C2H4)}‐κP)] (5) and [Pt(COMe)Cl(PPh3)2] (6) as well as with L1 to yield 3. Diacetylbis(amine)platinum(II) complexes cis‐[Pt(COMe)2(NH2R)2] (R = Bn, 2a; R = Et, 2b; Bn = benzyl) react with L1 with the substitution of one amine ligand to yield [Pt(COMe)2(NH2R)(PPh2{o‐C6H4CH(O2C2H4)}‐κP)] (R = Bn, 7a; R = Et, 7b). The unprotected 2‐(diphenylphosphanyl)benzaldehyde (L2) reacts with the platina‐β‐diketone 1 by oxidative C–H addition followed by reductive elimination of acetaldehyde to form [PtCl{PPh2(o‐C6H4CO)‐κP,κC}{PPh2(o‐C6H4CHO)‐κP}] (8). On the other hand, the reactions of diacetylbis(amine)platinum(II) complexes 2a/b and L2 proceeded with Schiff base formation and, thus, yielded complexes bearing hemiaminal–phosphane ligands, [Pt(COMe)2(PPh2{o‐C6H4CH(OH)(NHR)}‐κP,κN)] (R = Bn, 9a; R = Et, 9b), and imine–phosphane ligands, [Pt(COMe)2{PPh2(o‐C6H4CH=NR)‐κP,κN}] (R = Bn, 10a; R = Et, 10b). The identities of all platinum complexes were unambiguously proved by microanalyses, high‐resolution mass spectrometric investigations, NMR (1H, 13C, 31P, 195Pt) and IR spectroscopy, and single‐crystal X‐ray diffraction analyses (for 4, 9a). The differences in the reactivity of the aldehyde–phosphane L2 and its acetal‐protected derivative L1 are discussed.

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“…Calc. for C 40 Compound 17 was synthesized following a procedure similar to that described for 11, but using 2 and Ph 2 P(CH 2 ) 3 NH 2 as starting materials.…”

Section: [Pd{4-(coh)c 6 H 3 C(h)@ncy-c2n}{ph 2 Pc 4 H 2 (Nh)ch 2 Pphmentioning

confidence: 99%

“…Consequently, we decided to study the behavior of cyclometallated complexes 1 and 2 towards heterofunctionalized [P,N] and [P,O] phosphines: 2-(diphenylphosphino)ethylamine, 2-(diphenylphosphino)-1-propylamine and 2-(diphenylphosphino)benzaldehyde. The latter is one of the simplest bidentate [P,O] ligands and it exhibits two binding modes when the PCHO group acts as a chelating ligand [40], with the aldehyde moiety bonded to the metal in a r-fashion through the oxygen atom [41][42][43], or in a p-fashion through the carbon-oxygen double bond [44,45]. The coordination mode of the aldehyde is dependent on the transition metal, the oxidation state and the other ligands present in the compound.…”

Section: Introductionmentioning

confidence: 99%