2-Rhodaoxetanes: Their Formation of Oxidation of [RhI(ethene)]+ and Their Reactivity upon Protonation

Bruin, Bas de; Boerakker, Mark J.; Verhagen, Johanna A. W.; Gelder, René de; Smits, J.M.; Gal, Anton W.

doi:10.1002/(sici)1521-3765(20000117)6:2<298::aid-chem298>3.0.co;2-z

Cited by 59 publications

(54 citation statements)

References 14 publications

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“…Chemical shifts and coupling constants are summarised in Table 1. Other NMR data for [ 3 a ] + –[ 3 c ] + are very similar to those of the 'N 4 '‐2‐rhodaoxetanes [ 1 a ] + and [ 1 b ] + 10c…”

Section: Resultssupporting

confidence: 58%

“…This formation of [ 4 c ] + through dissociation of acetonitrile would be analogous to that observed in the gas phase by ESI‐MS. Generation of a species through dissociation of a 2‐methyl pyridyl arm of Bzbpa, through heterolytic dissociation of the 2‐rhodaoxetane Rh−O bond14, or through dissociation of the 2‐rhodaoxetane Rh−O bond after protonation of the rhodaoxetane oxygen10c, 15 are all considered less likely. In the presence of ethene, the 14‐electron species [(Bzbpa)Rh] + formed upon acetaldehyde elimination from [ 4 c ] + is trapped as the 16‐electron ethene complex [(Bzbpa)Rh I (C 2 H 4 )] + [ 2 c ] + (Scheme ).…”

Section: Resultsmentioning

confidence: 99%

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Enhanced Reactivity of 2-Rhodaoxetanes through a Labile Acetonitrile Ligand

Bruin¹,

Verhagen²,

Schouten³

et al. 2001

Chem. Eur. J.

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New cationic, square-planar, ethene complexes [(Rbpa)RhI(C2H4)]+ [2a]--[2c]+ (Rbpa = N-alkyl-N,N-di(2-pyridylmethyl)amine; [2a]+: alkyl =R=Me; [2b]+: R = Bu; [2c]+: R = Bz) have been selectively oxygenated in acetonitrile by aqueous hydrogen peroxide to 2-rhoda(III)oxetanes with a labile acetonitrile ligand, [(Rbpa)RhIII(kappa2-C,O-CH2CH2O-)(MeCN)]+, [3a]+-[3c]+. The rate of elimination of acetaldehyde from [(Rbpa)RhIII(kappa2-C,O-CH2CH2O-)(MeCN)]+ increases in the order R = Me< R = Bu< R = Bz. Elimination of acetaldehyde from [(Bzbpa)RhIII(kappa2-C,O-CH2CH2O)(MeCN)]+ [3c]+, in the presence of ethene results in regeneration of ethene complex [(Bzbpa)RhI(C2H4)]+ [2c]+, and closes a catalytic cycle. In the presence of Z,Z-1,5-cyclooctadiene (cod) the corresponding cod complex [(Bzbpa)RhI(cod)]+ [6c]+ is formed. Further oxidation of [3c]+ by H2O2 results in the transient formylmethyl-hydroxy complex [(Bzbpa)RhIII(OH)[kappa1-C-CH2C(O)H]]+ [5c]+.

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Section: Resultssupporting

confidence: 58%

Section: Resultsmentioning

confidence: 99%

Enhanced Reactivity of 2-Rhodaoxetanes through a Labile Acetonitrile Ligand

Bruin¹,

Verhagen²,

Schouten³

et al. 2001

Chem. Eur. J.

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“…For example, Zeise's salt [KPtCl 3 (C 2 H 4 )] and Cramer's dimer [Rh(C 2 H 4 ) 2 Cl] 2 , both commonly used organometallic starting materials, feature short C=C ethylene bond distances of 137.5 and 139.5 pm, respectively. In contrast, (MeTPA)Rh(C 2 H 4 )(BPh 4 ) [MeTPA= N ‐(6‐methyl‐2‐pyridyl) methyl‐ N , N ‐di(2‐pyridylmethyl)amine], features a much longer C=C bond distance of 145 pm, which corresponds to the metallacyclopropane end of the DCD spectrum. However, this method is generally qualitative, with many examples that fall in the middle of the spectrum being simply described as hybrids of the two resonance forms .…”

Section: Resultsmentioning

confidence: 99%

The Importance of Ligand‐Induced Backdonation in the Stabilization of Square Planar d¹⁰ Nickel π‐Complexes

Desnoyer

Behyan

et al. 2019

Chemistry A European J

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The electronic nature of Ni π‐complexes is underexplored even though these complexes have been widely postulated as intermediates in organometallic chemistry. Herein, the geometric and electronic structure of a series of nickel π‐complexes, Ni(dtbpe)(X) (dtbpe=1,2‐bis(di‐tert‐butyl)phosphinoethane; X=alkene or carbonyl containing π‐ligands), is probed using a combination of 31P NMR, Ni K‐edge XAS, Ni Kβ XES, and DFT calculations. These complexes are best described as square planar d10 complexes with π‐backbonding acting as the dominant contributor to M−L bonding to the π‐ligand. The degree of backbonding correlates with 2JPP from NMR and the energy of the Ni 1s→4pz pre‐edge in the Ni K‐edge XAS data, and is determined by the energy of the π*ip ligand acceptor orbital. Thus, unactivated olefinic ligands tend to be poor π‐acids whereas ketones, aldehydes, and esters allow for greater backbonding. However, backbonding is still significant even in cases in which metal contributions are minor. In such cases, backbonding is dominated by charge donation from the diphosphine, which allows for strong backdonation, although the metal centre retains a formal d10 electronic configuration. This ligand‐induced backbonding can be formally described as a 3‐centre‐4‐electron (3c‐4e) interaction, in which the nickel centre mediates charge transfer from the phosphine σ‐donors to the π*ip ligand acceptor orbital. The implications of this bonding motif are described with respect to both structure and reactivity.

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“…The products can be isolated as the PF 6 , BF 4 or BPh 4 salts by precipitation, or as the chlorides by evaporation of the solvent.…”

Section: Synthesismentioning

confidence: 99%

“…These ligands contain the same donor groups as the dipicolylamine (DPA) and tripicolylamine (TPA) ligands that we have studied previously, [5,6] rather stable and thus provide a convenient starting point for further studies using more labile olefins. One Rh complex of L 4 has been reported, [9] but no Ir complexes.…”

Section: Introductionmentioning

confidence: 99%