Trimethoxyphenylverbindungen, III. 3.4.5‐Trimethoxy‐phenylessigsäure

Hypercoordination, Bond Length Alterations, Sub-van der Waals Interatomic DistancesIn an 8-dimethylamino-naphth-l-yl-phosphorane a dative N-P bond forms in spite of the spacer properties of the naphthalene skeleton. Its "normal" length, 213.2 pm, much too short to fill the peri space, forces the Cio skeleton into severe distortion. In the light of these properties peri distances d(N-P/Si) 250 pm in 8-dimethylamino-naphth-l-yl-phosphines, -silanes etc.are recognized as evidence for steric hindrance.für Naturforschung, Tübingen -www.znaturforsch.com K

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“…DAN-silanes and -phosphines are the consequence of steric hindrance rather than of dative N->Si/P interactions [28].…”

Section: Introductionmentioning

confidence: 99%

peri-Interactions in Naphthalenes, 4 [1]. Hypercoordination in 8-Dimethylamino-naphth-1-yl Phosphorus Compounds

Schiemenz

Pörksen

Näther

2000

Zeitschrift Für Naturforschung B

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“…The interactions between peri-substituents at the naphthalene skeleton have fascinated chemists for a long time. The exocyclic bonds emanating from them would be parallel so that this would also be the distance of peri-substituents provided that the two bonds are of equal length [1,[27][28][29][30][31]. The exocyclic bonds emanating from them would be parallel so that this would also be the distance of peri-substituents provided that the two bonds are of equal length [1,[27][28][29][30][31].…”

Section: Discussionmentioning

confidence: 99%

“…intersubstituent distances d(C···C) and d(N···N) between PD and Σr(vdW)) and even Franck's paper concerning the sub-van der Waals d(C···C) attributed to steric strain in the former [38] had received attention [7,26] and though it had occasionally been acknowledged that in the rigid naphthalene system repulsive sub-van der Waals distances occur [7], the claim was based solely on the fact that d(N···Si/P) was invariably much shorter than Σr(vdW) 5,6) . For them, the conditions of intramolecular coordination 5) Other arguments, presented in support of dative NǞSi/P interactions, ultimately rest on the d(N···Si/P) < Σr(vdW) criterion; the underlying phenomena can easily be rationalized differently, e. g., NMR phenomena [27,28,33]. The rigidity of the naphthalene system was taken into account by the description of this NǞSi/P interaction as an enforced dative interaction 7) [8,10], conditioned by the geometry of the naphthalene system [7,13,60] which was believed to facilitate such interactions [5,6,12,61].…”

Section: -1naphthyl]phosphine and Tris[2-{(dimethylamino)methyl}phenymentioning

confidence: 99%

Dative N→P/Si Interactions — A Historical Approach [1]

Schiemenz¹

2002

Z. anorg. allg. Chem.

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The dative NǞSi/P interactions in 8-dimethylaminonaphth-1-yl-silanes and phosphorus compounds are largely an artefact which originated from insufficient perusal of the pertinent literature. Dative NǞP/Si Wechselwirkungen ؊ Eine historische Untersuchung [1]Inhaltsübersicht. Die dativen NǞSi/P-Wechselwirkungen in 8-Dimethylamino-naphth-1-yl-silanen und -phosphorverbindungen 1) Cases in which short distances d(N···Si/P) point to attractive interatomic interactions and in which the arrangement around Si/P has been described as (distorted) trigonal-bipyramidal or, in case of hexacoordination, as octahedral, are excluded from the following discussion. -van der Waals distances sind meist ein Artefakt als Folge der Nichtberücksichtigung der einschlägigen Literatur.

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“…Such choice is surprising be cause the geom etry o f the fairly rigid naphthalene skeleton puts the peri substituents at a "natural" dis tance o f ca. 250 pm [10,11], much too long for a conventional bonding interaction [12]. The form a tion o f a dative bond D^A [13] of norm al length would require a considerable distortion of the Cio skeleton w hose energetic bill could be paid only by a strong p eri bond (such as a C-C or an am ide N-CO bond [14]).…”

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confidence: 99%

peri-Interactions in Naphthalenes, 3 [1]. On Hypercoordination in 8-Dimethylamino-naphth-1-yl-phosphonium salts and -phosphines

Schiemenz

Bukowski

Eckholtz

et al. 2000

Zeitschrift Für Naturforschung B

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In (alkyl)di(aryl)(8-dim ethylamino-naphth-l-yl)phosphonium salts and in the parent phos phines, there is no experimental evidence of dative N -^P interactions. Conclusions to the contrary are based on the choice of improper standards of comparison.In tro d u c tio n /?e/7 -D isubstituted naphthalenes continue to be cherished objects o f research for the investigation of donor/acceptor (D ->A) interactions. This includes com pounds w ith donor substituents D o f only m od erate nucleophilicity and "acceptor" substituents A w hose electrophilicity is, at best, rather w eak or even doubtful. E .g ., a /?m -dim ethylam ino group or even a m ethoxy group has frequently been cho sen as the donor substituent [2 ], though 1-dim ethylam ino-naphthalene and 1 -m ethoxy-naphthalene are o f the dim ethylaniline and anisole type, respec tively.A m ong tertiary am ines, dim ethylaniline is a fairly w eak nucleophile. In 8-substituted 1-dim ethylam ino-naphthalenes, sterical hindrance in the peri space forces the (C H^^N group out of the Cio plane (see form ula 1) [3] so that efficient resonance o f the lone pair at N and the arom atic system is precluded; however, the N atom, bound to tw o sp3-carbons and one sp2 -carbon atom , neverthe less is a m uch poorer nucleophile than in aliphatic tertiary am ines (for com parisonmutatis mutan dis -note that 1-dim ethylam ino-naphthalene is less basic and N ,N ,2,6-tetram ethyl-aniline (2) only very slightly more basic than dim ethylaniline w hereas all three o f them are less basic than trim ethylam ine by more than five pow ers o f ten in the K B scale [4]). In 1 -m ethoxy-naphthalenes, sterical inhibition of res onance is m uch sm aller even in the presence of 8-substituents, and the cr-donicity of the anisole-type oxygen atom is, indeed, very poor.Am ong the "acceptor" substituents, am ide [2], silyl [5] and phosphino groups [6 -9] have been used w hich range, at best, at the bottom end of any electrophilicity scale. Such choice is surprising be cause the geom etry o f the fairly rigid naphthalene skeleton puts the peri substituents at a "natural" dis tance o f ca. 250 pm [10,11], much too long for a conventional bonding interaction [12]. The form a tion o f a dative bond D^A [13] of norm al length would require a considerable distortion of the Cio skeleton w hose energetic bill could be paid only by a strong p eri bond (such as a C-C or an am ide N-CO bond [14]). For the bonding interaction between a weak nucleophile and a p o o r electrophile, the naph thalene skeleton w ould act as a spacer which pre vents the substituents from com ing into bonding distance.Though still very m oderately so, a phosphonium phosphorus atom is a better electrophile than P in phosphines [15]. Earlier, we had investi gated the possibility o f a dative (C H 3)2N M P + in teraction in (alkyl)(8-dim ethylam ino-naphth-l-yl)-[=D A N ]di(phenyl)phosphonium salts [16]. Such in teraction could be described either as an isomerism (3A ^ 3B) or as a bond/no bond resonance (3A <->• 3B) [16]. In the form er case...

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Trimethoxyphenylverbindungen, III. 3.4.5‐Trimethoxy‐phenylessigsäure

Cited by 12 publications

References 47 publications

peri-Interactions in Naphthalenes, 4 [1]. Hypercoordination in 8-Dimethylamino-naphth-1-yl Phosphorus Compounds

peri-Interactions in Naphthalenes, 4 [1]. Hypercoordination in 8-Dimethylamino-naphth-1-yl Phosphorus Compounds

Dative N→P/Si Interactions — A Historical Approach [1]

peri-Interactions in Naphthalenes, 3 [1]. On Hypercoordination in 8-Dimethylamino-naphth-1-yl-phosphonium salts and -phosphines

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