1,2‐<i>P</i>,<i>N</i>‐Bidentate Ferrocenyl Ligands

Zhou, Yong; Hou, Xiaomei

doi:10.1002/9783527628841.ch5

Cited by 4 publications

(1 citation statement)

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“…Metal complexes bearing N,P -chelate ligands are ubiquitous in organometallic and coordination chemistry and usually find applications in the field of homogeneous catalysis . Within this type of ligands, N -phosphinoamidines and N -phosphinoguanidines , have attracted increasing interest among the inorganic chemistry community, especially in the last two decades.…”

Section: Introductionmentioning

confidence: 99%

Reactivity of N-Phosphinoguanidines of the Formula (HNR)(Ph₂PNR)C(NAr) toward Main Group Metal Alkyls: Facile Ligand Rearrangement from N-Phosphinoguanidinates to Phosphinimine-Amidinates

et al. 2020

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We report the reactivity of N-phosphinoguanidines of the formula (HNR)(Ph 2 PNR)C(NAr) (R = i Pr and Ar = 2,6-i Pr 2 C 6 H 3 [Dipp] for 1a, R = i Pr and Ar = 2,4,6-Me 3 C 6 H 2 [Mes] for 1b, and R = Cy and Ar = Dipp for 1c), prepared in high yields from the corresponding trisubstituted guanidines, toward main group metal alkyls AlMe 3 , ZnEt 2 , Mg n Bu 2 , and n BuLi to obtain novel phosphinoguanidinato and phosphinimine-amidinato compounds. Reactions of 1a−c with AlMe 3 at room temperature led to the kinetic phosphinoguanidinato products [Al{κ 2 -N,N′-(NR)C(NAr)(NRPPh 2 )}Me 2 ] (2a−c), whereas the mild heating (60−80 °C) of solutions of 2a−c give the thermodynamic phosphinimine-amidinato products [Al{κ 2 -N,N′-(NR)C(NAr)(PPh 2 NR)}Me 2 ] (3a−c) after ligand rearrangement. The reactions of equimolar amounts of 1a−c and ZnEt 2 initially give solutions containing unstable phosphinoguanidinato compounds [Zn{κ 2 -N,P-(NR)C(NAr)(NRPPh 2 )}-Et] (4a−c), which rearrange upon mild heating to the phosphinimine-amidinato derivatives [Zn{κ 2 -N,N′-(NR)C(NAr)(PPh 2 NR)}Et] (6a−c). Bis(phosphinoguanidinato) compounds [Zn{κ 2 -N,P-(NR)C(NAr)-(NRPPh 2 )} 2 ] (5a−c) can be obtained under mild conditions (<45 °C) in THF, whereas bis(phosphinimine-amidinato) compounds [Zn{κ 2 -N,N′-(NR)C(NAr)(PPh 2 NR)} 2 ] (7a−c) are also accessible under more forcing conditions (55−100 °C) from (i) ZnEt 2 and 1b,c (2 equiv), (ii) 6a and 1a, or (iii) 5b,c. Equimolar mixtures of Mg n Bu 2 and 1a−c in THF at room temperature give unstable phosphinimine-amidinato monoalkyl products [Mg{κ 2 -N,N′-(NR)C(NAr)(PPh 2 NR)} n Bu(THF) 2 ] (8a−c), whereas 2 equiv of 1a,b are required to reach the bischelate compounds [Mg{κ 2 -N,N′-(N i Pr)C(NAr)(PPh 2 N i Pr)} 2 ] (9a,b). Finally, phosphinoguanidinato compounds [Li{κ 2 -N,P-(NR)C(NDipp)(NRPPh 2 )}(THF) 2 ] (10a,c) were obtained in the reactions of 1a,c with n BuLi in THF under ambient conditions. The removal of the solvent from solutions of 10a,c under partial vacuum leads to the dinuclear compounds [Li 2 {μ−κ 2 -N,N′:κ 1 -N-(NR)C(NDipp)(NRPPh 2 )} 2 (THF) 2 ] (11a,c) after the decoordination of one of the THF molecules in 10a,c and dimerization. Heating solutions of 10a,c at 60 °C triggers ligand rearrangement to give phosphinimineamidinato compounds [Li{κ 2 -N,N′-(NR)C(NDipp)(PPh 2 NR)}(THF) 2 ] (12a ,c). We also propose a mechanism for the ligand rearrangement reaction from 10a to give 12a, supported by DFT calculations, which fits nicely with our experimental results. It essentially involves a carbodiimide deinsertion reaction followed by a [3 + 2] cycloaddition between the resulting lithium phosphinoamide and the carbodiimide.

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Section: Introductionmentioning

confidence: 99%

Reactivity of N-Phosphinoguanidines of the Formula (HNR)(Ph₂PNR)C(NAr) toward Main Group Metal Alkyls: Facile Ligand Rearrangement from N-Phosphinoguanidinates to Phosphinimine-Amidinates

et al. 2020

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ChemInform Abstract: 1,2‐P,N‐Bidentate Ferrocenyl Ligands

Zhou

Hou

2011

ChemInform

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Ruthenium Complexes of Phosphino-Substituted Ferrocenyloxazolines in the Asymmetric Hydrogenation and Transfer Hydrogenation of Ketones: A Comparison

et al. 2012

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Three novel routes have been developed for the synthesis of ferrocenylbased phosphino-oxazolines in which the phosphino unit is attached to a ferrocenylmethyl or a ferrocenylethyl side chain. In two of the routes the phosphino-substituted ethyl side chain was built up diastereoselectively. Ruthenium complexes of the type [RuCl 2 PPh 3 (L)] of 12 bidentate phosphine-oxazoline ligands were synthesized, characterized, and tested in the transfer hydrogenation of acetophenone. For the best performing complexes a total of 12 additional ketones were screened in transfer hydrogenations and hydrogenations under transfer hydrogenation conditions. Two catalyst precursors in particular delivered products with an enantiomeric excess of up to 98% in transfer hydrogenations and 99% ee in hydrogenations. The transfer hydrogenation results obtained with all novel ligands were compared to those of two well-established FOXAP ligands. Furthermore, a qualitative comparison with the hydrogenation data was carried out. In both cases surprising similarities in product enantiomeric excess and product absolute configuration were found. Attempts were made to rationalize some of the observed features by considering a transition-state model. The molecular structures of one synthesis intermediate, two catalyst precursors, and two corresponding acetonitrile complexes were studied by X-ray diffraction.

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1,2‐P,N‐Bidentate Ferrocenyl Ligands

Cited by 4 publications

References 124 publications

Reactivity of N-Phosphinoguanidines of the Formula (HNR)(Ph₂PNR)C(NAr) toward Main Group Metal Alkyls: Facile Ligand Rearrangement from N-Phosphinoguanidinates to Phosphinimine-Amidinates

Reactivity of N-Phosphinoguanidines of the Formula (HNR)(Ph₂PNR)C(NAr) toward Main Group Metal Alkyls: Facile Ligand Rearrangement from N-Phosphinoguanidinates to Phosphinimine-Amidinates

ChemInform Abstract: 1,2‐P,N‐Bidentate Ferrocenyl Ligands

Ruthenium Complexes of Phosphino-Substituted Ferrocenyloxazolines in the Asymmetric Hydrogenation and Transfer Hydrogenation of Ketones: A Comparison

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1,2‐P,N‐Bidentate Ferrocenyl Ligands

Cited by 4 publications

References 124 publications

Reactivity of N-Phosphinoguanidines of the Formula (HNR)(Ph2PNR)C(NAr) toward Main Group Metal Alkyls: Facile Ligand Rearrangement from N-Phosphinoguanidinates to Phosphinimine-Amidinates

Reactivity of N-Phosphinoguanidines of the Formula (HNR)(Ph2PNR)C(NAr) toward Main Group Metal Alkyls: Facile Ligand Rearrangement from N-Phosphinoguanidinates to Phosphinimine-Amidinates

ChemInform Abstract: 1,2‐P,N‐Bidentate Ferrocenyl Ligands

Ruthenium Complexes of Phosphino-Substituted Ferrocenyloxazolines in the Asymmetric Hydrogenation and Transfer Hydrogenation of Ketones: A Comparison

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Reactivity of N-Phosphinoguanidines of the Formula (HNR)(Ph₂PNR)C(NAr) toward Main Group Metal Alkyls: Facile Ligand Rearrangement from N-Phosphinoguanidinates to Phosphinimine-Amidinates

Reactivity of N-Phosphinoguanidines of the Formula (HNR)(Ph₂PNR)C(NAr) toward Main Group Metal Alkyls: Facile Ligand Rearrangement from N-Phosphinoguanidinates to Phosphinimine-Amidinates