Synthesis and N–C bond cleavage reactions for cyclic phosphazenium dications

Phosphazenium cations were first characterized 60 years ago and yet little is known of their reactivity. The bidentate phosphonium dicationic salts [(C<sub>6</sub>H<sub>4</sub>)(PPh<sub>2</sub>F)<sub>2</sub>][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>]<sub>2</sub>2 and [(C<sub>6</sub>H<sub>4</sub>)(PPh<sub>2</sub>Cl)<sub>2</sub>][Cl]<sub>2</sub>3 were prepared. Reaction of 2 with (Me<sub>3</sub>Si)<sub>2</sub>NMe gave the phosphazenium dication [(C<sub>6</sub>H<sub>4</sub>)(PPh<sub>2</sub>)<sub>2</sub>(μ-NMe)][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>]<sub>2</sub>4, while reaction of 3 with two equivalents of Me<sub>2</sub>N(SiMe<sub>3</sub>) gave the related dication [(C<sub>6</sub>H<sub>4</sub>)(PPh<sub>2</sub>NMe<sub>2</sub>)<sub>2</sub>][Cl]<sub>2</sub>5. Compound 3 also reacted with (Me<sub>3</sub>Si)<sub>2</sub>NH affording the monocationic salt [(C<sub>6</sub>H<sub>4</sub>)(PPh<sub>2</sub>)<sub>2</sub>(μ-N)]Cl 6, with the liberation of HCl. Interestingly 4 reacted with [nBu<sub>4</sub>N]Cl generating the related salt [(C<sub>6</sub>H<sub>4</sub>)(PPh<sub>2</sub>)<sub>2</sub>(μ-N)][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>] 6' with concurrent formation of MeCl. This reactivity was extended to [(C<sub>2</sub>H<sub>4</sub>)(PPh<sub>2</sub>F)<sub>2</sub>][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>]<sub>2</sub>7 which afforded [(C<sub>2</sub>H<sub>4</sub>)(PPh<sub>2</sub>)<sub>2</sub>(μ-NR)][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>]<sub>2</sub> (R = Me 8, CH<sub>2</sub>CHCH<sub>2</sub>9, CH<sub>2</sub>Ph 10) upon reaction with (Me<sub>3</sub>Si)<sub>2</sub>NR. These dications were shown to react with [nBu<sub>4</sub>N]Cl affording [(CH<sub>2</sub>PPh<sub>2</sub>)<sub>2</sub>(μ-N)][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>] 11 and the corresponding alkyl-chloride. The mechanism of these N-C bond cleavage reactions is considered.

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Journal
Dalton Transactions
Published
2024-11-13
DOI
https://doi.org/10.1039/d4dt02990a
Primary Topic
Organophosphorus compounds synthesis
Type
article
Field-Weighted Citation Impact
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article

Synthesis and N–C bond cleavage reactions for cyclic phosphazenium dications

Douglas W. Stephan, Amir Yeganeh-Salman, Jason Yeung, Linkun Miao
Dalton Transactions
Organophosphorus compounds synthesis
article

Synthesis and N–C bond cleavage reactions for cyclic phosphazenium dications

Douglas W. Stephan, Amir Yeganeh-Salman, Jason Yeung, Linkun Miao
article en

Abstract

Phosphazenium cations were first characterized 60 years ago and yet little is known of their reactivity. The bidentate phosphonium dicationic salts [(C<sub>6</sub>H<sub>4</sub>)(PPh<sub>2</sub>F)<sub>2</sub>][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>]<sub>2</sub>2 and [(C<sub>6</sub>H<sub>4</sub>)(PPh<sub>2</sub>Cl)<sub>2</sub>][Cl]<sub>2</sub>3 were prepared. Reaction of 2 with (Me<sub>3</sub>Si)<sub>2</sub>NMe gave the phosphazenium dication [(C<sub>6</sub>H<sub>4</sub>)(PPh<sub>2</sub>)<sub>2</sub>(μ-NMe)][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>]<sub>2</sub>4, while reaction of 3 with two equivalents of Me<sub>2</sub>N(SiMe<sub>3</sub>) gave the related dication [(C<sub>6</sub>H<sub>4</sub>)(PPh<sub>2</sub>NMe<sub>2</sub>)<sub>2</sub>][Cl]<sub>2</sub>5. Compound 3 also reacted with (Me<sub>3</sub>Si)<sub>2</sub>NH affording the monocationic salt [(C<sub>6</sub>H<sub>4</sub>)(PPh<sub>2</sub>)<sub>2</sub>(μ-N)]Cl 6, with the liberation of HCl. Interestingly 4 reacted with [nBu<sub>4</sub>N]Cl generating the related salt [(C<sub>6</sub>H<sub>4</sub>)(PPh<sub>2</sub>)<sub>2</sub>(μ-N)][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>] 6' with concurrent formation of MeCl. This reactivity was extended to [(C<sub>2</sub>H<sub>4</sub>)(PPh<sub>2</sub>F)<sub>2</sub>][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>]<sub>2</sub>7 which afforded [(C<sub>2</sub>H<sub>4</sub>)(PPh<sub>2</sub>)<sub>2</sub>(μ-NR)][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>]<sub>2</sub> (R = Me 8, CH<sub>2</sub>CHCH<sub>2</sub>9, CH<sub>2</sub>Ph 10) upon reaction with (Me<sub>3</sub>Si)<sub>2</sub>NR. These dications were shown to react with [nBu<sub>4</sub>N]Cl affording [(CH<sub>2</sub>PPh<sub>2</sub>)<sub>2</sub>(μ-N)][B(C<sub>6</sub>F<sub>5</sub>)<sub>4</sub>] 11 and the corresponding alkyl-chloride. The mechanism of these N-C bond cleavage reactions is considered.

Dalton TransactionsVol. 54(1)
Ningbo University (CN), University of Toronto (CA)
University of Toronto, Natural Sciences and Engineering Research Council of Canada
Openalex Percentile: Top 85%
Organophosphorus compounds synthesis
DOISourceOpenAlex
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