31P-31P spin-spin coupling in complexes containing two phosphorus ligands

Ogilvie, F. B.; Jenkins, John M; Verkade, John G.

doi:10.1021/ja00710a022

Cited by 78 publications

(29 citation statements)

References 6 publications

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“…The 31 P NMR spectrum contained two pairs of PPh 3 and CH 2 PPh 2 signals. The CH 2 PPh 2 signals were coupled, with a value (432 Hz) characteristic of palladium( II ) complexes with trans phosphine ligands 28. Hence, the structure shown in Scheme , SP ‐4‐2 ( S , S )‐ 14 ,23 is proposed.…”

Section: Resultsmentioning

confidence: 92%

Synthesis, Structure, and Reactivity of Palladacycles That Contain a Chiral Rhenium Fragment in the Backbone: New Cyclometalation and Catalyst Design Strategies

Friedlein

Kromm

Hampel

et al. 2006

Chemistry A European J

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The bromocyclopentadienyl complex [(eta5-C5H4Br)Re(CO)3] is converted to racemic [(eta5-C5H4Br)Re(NO)(PPh3)(CH2PPh2)] (1 b) similarly to a published sequence for cyclopentadienyl analogues. Treatment of enantiopure (S)-[(eta5-C5H5)Re(NO)(PPh3)(CH3)] with nBuLi and I2 gives (S)-[(eta5-C5H4I)Re(NO)(PPh3)(CH3)] ((S)-6 c; 84 %), which is converted (Ph3C+ PF6 -, PPh2H, tBuOK) to (S)-[(eta5-C5H4I)Re(NO)(PPh3)(CH2PPh2)] ((S)-1 c). Reactions of 1 b and (S)-1 c with Pd[P(tBu)3]2 yield [{(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)Pd(mu-X)}2] (10; X = b, Br, rac/meso, 88 %; c, I, S,S, 22 %). Addition of PPh3 to 10 b gives [(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)Pd(PPh3)(Br)] (11 b; 92 %). Reaction of (S)-[(eta5-C5H5)Re(NO)(PPh3)(CH2PPh2)] ((S)-2) and Pd(OAc)(2) (1.5 equiv; toluene, RT) affords the novel Pd3(OAc)4-based palladacycle (S,S)-[(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)Pd(mu-OAc)2Pd(mu-OAc)2Pd(mu-PPh2CH2)(Ph3P)(ON)Re(eta5-C5H4)] ((S,S)-13; 71-90 %). Addition of LiCl and LiBr yields (S,S)-10 a,b (73 %), and Na(acac-F6) gives (S)-[(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)Pd(acac-F6)] ((S)-16, 72 %). Reaction of (S,S)-10 b and pyridine affords (S)-[(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)Pd(NC5H5)(Br)] ((S)-17 b, 72 %); other Lewis bases yield similar adducts. Reaction of (S)-2 and Pd(OAc)2 (0.5 equiv; benzene, 80 degrees C) gives the spiropalladacycle trans-(S,S)-[{(eta5-C5H4)Re(NO)(PPh3)(mu-CH2PPh2)}2Pd] (39 %). The crystal structures of (S)-6 c, 11 b, (S,S)- and (R,R)-132 C7H8, (S,S)-10 b, and (S)-17 b aid the preceding assignments. Both 10 b (racemic or S,S) and (S)-16 are excellent catalyst precursors for Suzuki and Heck couplings.

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Section: Resultsmentioning

confidence: 92%

Synthesis, Structure, and Reactivity of Palladacycles That Contain a Chiral Rhenium Fragment in the Backbone: New Cyclometalation and Catalyst Design Strategies

Friedlein

Kromm

Hampel

et al. 2006

Chemistry A European J

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“…Compounds of this type are expected to be of importance in the direct measurement of three-bond P-P c o~~p l i n g constants in n.m.r. spectroscopy (19).…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Some New Phosphino Acetylenes

Carty¹,

Hota²,

Ng³

et al. 1971

Can. J. Chem.

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“…2 J PP scalar coupling constants between 1150 and 1180 Hz for all heterocomplexes verified the exclusive formation of trans complexes, which completely, but slowly convert into cis complexes with appropriate 2 J PP coupling constants between 95 and 105 Hz. [13] This isomerization to the thermodynamically controlled cis complexes [12] is evident in the 31 P NMR spectra of the ligand combinations 1/2 and 1/2* in Figure 3. In addition, the interaction pattern is extremely similar within all cis complexes Pd(L)(L')Cl 2 and closely resembles that in the known crystal structure [14] of cis-Pd2* 2 Cl 2 (see below and the Supporting Information).…”

Section: Methodsmentioning

confidence: 96%

The Supramolecular Balance for Transition‐Metal Complexes: Assessment of Noncovalent Interactions in Phosphoramidite Palladium Complexes

Hartmann

Gschwind

2013

Angew Chem Int Ed

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For some decades bidentate ligands have prevailed in the field of transition-metal catalysis. [1] The superiority of bidentate ligands over monodentates was explained by the higher conformational rigidity of the ligands and their stronger coordination to the metal. [1b] However, in the last few years monodentate ligands have experienced a revival, and moreover interest in rational ligand design has grown tremendously: [2] Monodentate ligands have been developed which are able to self-assemble in the coordination sphere of the metal center through weak ligand-ligand interactions, such as hydrogen bonding [2d-g] and metal-bridged coordinative bonding. [2h-j] However, the use of weak interligand interactions based on CH-p and p-p interactions for rational ligand design is still very challenging. [2a] Various experimental and theoretical approaches have been devised to investigate and quantify noncovalent interactions such as hydrogen bonding and p-p stacking and their dependency on solvent properties. [3] The "double-mutant cycles" developed by Fersht et al. have become a powerful thermodynamic tool for the experimental quantification of single noncovalent interactions in proteins and in host-guest model systems. [4] In addition the "molecular torsion balance" developed by Wilcox and co-workers [5] has been applied to quantify CH-p interactions and aromatic interactions in organic molecules. [3a,b] However, no method has been presented to measure the contribution of noncovalent ligandligand interactions within transition-metal complexes to date. For guest-host systems binding constants are typically used for the quantification of noncovalent interactions. However, in the case of metal complexes the binding constant reflects not only noncovalent interactions, but primarily metal-ligand binding based on electronic properties such as the s-donor/pacceptor properties of the ligands. Therefore, for the measurement of pure ligand-ligand interactions, covalent and noncovalent contributions to the binding constant must be separated. In addition, possible changes in the electronic and electrostatic properties must be considered, that is, changes in the stereoelectronic properties of the metal-ligand bond and of the electrostatic contributions of the dipoles due to reorientation within the ligands upon cis-trans isomerization. To the best of our knowledge, it was previously not possible to separate and quantify the contributions of noncovalent interactions (e.g. CH-p and p-p interactions) from stereoelectronic properties and electrostatic interactions in transition-metal complexes.In this study we present the first method for the quantification of noncovalent ligand-ligand interactions in transition-metal complexes separated from stereoelectronic and electrostatic effects. Based on the formation trends of different phosphoramidite palladium complexes the free energy difference DDG caused by the formation of additional attractive CH-p interactions was determined. Moreover, 1 H 1 H NOESY measurements and 1 H chemical shi...

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31P-31P spin-spin coupling in complexes containing two phosphorus ligands

Cited by 78 publications

References 6 publications

Synthesis, Structure, and Reactivity of Palladacycles That Contain a Chiral Rhenium Fragment in the Backbone: New Cyclometalation and Catalyst Design Strategies

Synthesis, Structure, and Reactivity of Palladacycles That Contain a Chiral Rhenium Fragment in the Backbone: New Cyclometalation and Catalyst Design Strategies

Synthesis of Some New Phosphino Acetylenes

The Supramolecular Balance for Transition‐Metal Complexes: Assessment of Noncovalent Interactions in Phosphoramidite Palladium Complexes

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