A hydrogen atom in an organoplatinum-amine system. 1. Synthesis and spectroscopic and crystallographic characterization of novel zwitterionic complexes with a Pt(II)-.cntdot..cntdot..cntdot.H-N+ unit

Koten, Gerard van; Wehman-Ooyevaar, Ingrid C. M.; Grove, David M.; Kooijman, Huub; Sluis, P. van der; Spek, Anthony L.

doi:10.1021/ja00051a025

Cited by 101 publications

(74 citation statements)

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“…These "special" hydrogen bonds are sometimes termed "Low Barrier Hydrogen Bonds" (LBHB) and are postulated as transition states in several organic and enzyme catalytic events. 33,37 The values of H(r) reported for the complexes investigated here are the most negative ones calculated for M···H-X interactions 11,34 (see Table 4), and certainly, the Pt-H distances calculated or measured by X ray (complexes 1 and B, see Table 3), are among the shortest reported for this kind of complexes 6,15,16 Some authors have stated that the shorter the Pt···H contact, the more negative the value of H(r) is and the greater the downfield displacement of the interacting hydrogen is in the 1 H NMR spectra. 11 In the case of the four complexes studied here, the calculated or measured values of the Pt-H distances are very similar, ranging from 2.09 Å to 2.19 Å (see Table 1).…”

Section: Synthesis and Characterization Of The Complexes [Pt(c 6 F 5 mentioning

confidence: 61%

Synthesis, Characterization, And Computational Study of Complexes Containing Pt···H Hydrogen Bonding Interactions

2013

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Section: Synthesis and Characterization Of The Complexes [Pt(c 6 F 5 mentioning

confidence: 61%

Synthesis, Characterization, And Computational Study of Complexes Containing Pt···H Hydrogen Bonding Interactions

2013

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“…Extensive experimental and computational evidence has also been provided for the involvement of a PtOHN hydrogen bond in zwitterionic Pt(II) complexes with a properly situated ammonium group (31)(32)(33). By x-ray crystallography an almost linear three-center PtOHN arrangement was observed (34). In this case, oxidation to Pt(IV) lead to the tautomeric metal hydride system.…”

Section: Resultsmentioning

confidence: 99%

OH–Pd(0) interaction as a stabilizing factor in palladium-catalyzed allylic alkylations

Hallman

Frölander²,

Wondimagegn³

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

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In palladium-catalyzed alkylations of allylic acetates with malonate as nucleophile, catalysts with oxazoline ligands bearing hydroxymethyl substituents in 4-position have been shown by density functional theory computations to undergo a conformational change on nucleophilic attack, which is accompanied by reduction of Pd(II) to Pd(0). The conformations of the Pd(0) complexes were shown to be governed by the presence of a hydrogen bond with the metal center acting as a hydrogen bond acceptor. The conformational change, which is absent in catalysts with O-alkylated analogs, largely affects the enantioselectivity of the catalytic process. This process is a previously uninvestigated example of where this type of weak hydrogen bond has been shown to influence the stereochemistry of a chemical reaction.A symmetric metal catalysis constitutes a powerful method for the preparation of enantiopure chiral compounds (1-3). To achieve high selectivity in the catalytic reactions, proper design of chiral ligands having the ability to transfer the chiral information to the reacting substrates is required. Proper design is usually accomplished by consideration of the steric and electronic demands of the catalytic process under study. Secondary interactions between the chiral ligand and the reacting species may influence the conformation of the catalyst, thereby affecting the stereoselectivity (4). At the same time, such interactions may be used to tune the electronic properties, resulting in increased reactivity of the catalytic system. Several examples of increased stereoselectivity and͞or acceleration of catalytic processes by ligands containing properly situated hydroxy groups have been reported. In rhodium-catalyzed hydrogenations of olefins, hydroxy substituents in the ligands have been shown to have remarkable effects. Thus, Knowles et al. (5) observed that a (R,R)-1,2-ethanediylbis[(2-methoxyphenyl)-phenylphosphine] derivative with the methoxy groups replaced by hydroxy groups provided high enantioselectivity, although it was at the expense of the high reactivity. Later, Börner (ref. 6 and references cited therein) noted similar effects for other types of ligands and provided evidence that properly situated hydroxy groups in the ligands coordinate to the cationic rhodium center by their oxygen lone pairs. Hayashi and coworkers (7-9) observed an accelerating effect by hydroxy groups in palladium-catalyzed allylic alkylations by using ferrocenylphosphine ligands. The effect was believed to be caused by an attractive interaction involving hydrogen bonding between a hydroxy group in the ligand and the nucleophile.We recently found that use of 2-(1-hydroxyalkyl)-(1a) and 2-(1-alkoxyalkyl)pyridinooxazolines (1b) as ligands in palladium-catalyzed allylic alkylations with malonate resulted in profoundly different enantioselectivities, ligands with (R*,R*)-configuration of the former type and those with (R*,S*)-configuration of the latter type, resulting in higher enantioselectivity than their diastereomers (10). This difference...

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“…This description indicates a sulfur valence orbital hybridization intermediate between {sp 3 } and {sp 2 + p}. 1a,2b In 2 the nonhydrogen-bonded sulfur atom, S(2), affords a Pd-S bond length of 2.3367(16) Å, which is slightly longer than the hydrogenbonded Pd-S(1) bond length of 2.3301 (14) Å. This small difference in bond length is consistent with the N-H‚‚‚S hydrogen bond utilizing a sulfur orbital which has nearly pure p character and which is orthogonal to, and therefore has little influence on, the Pd-S σ-orbital.…”

Section: Resultsmentioning

confidence: 99%

“…In particular, N-H‚‚‚X interactions are believed to be important in a number of metal-complex-catalyzed processes, 13 and in a related context we have investigated the occurrence of N-H‚‚‚Pt and N-H‚‚‚Br interactions in organometallic species. 14 …”

Section: Resultsmentioning

confidence: 99%

Palladium(II) Arenethiolates with Chelating Diamines: Formation of N−H···S Hydrogen Bonds with Protonated N,N,N‘,N‘-Tetramethylethylenediamine

et al. 1996

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A hydrogen atom in an organoplatinum-amine system. 1. Synthesis and spectroscopic and crystallographic characterization of novel zwitterionic complexes with a Pt(II)-.cntdot..cntdot..cntdot.H-N+ unit

Cited by 101 publications

References 1 publication

Synthesis, Characterization, And Computational Study of Complexes Containing Pt···H Hydrogen Bonding Interactions

Synthesis, Characterization, And Computational Study of Complexes Containing Pt···H Hydrogen Bonding Interactions

OH–Pd(0) interaction as a stabilizing factor in palladium-catalyzed allylic alkylations

Palladium(II) Arenethiolates with Chelating Diamines: Formation of N−H···S Hydrogen Bonds with Protonated N,N,N‘,N‘-Tetramethylethylenediamine

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