Low-Valent Chemistry: An Alternative Approach to Phosphorus-Containing Oligomers

Abstract

A convenient preparative approach to low-valent phosphorus-rich oligomers is presented. Ligand substitution reactions involving anionic diphosphine ligands of the form [(PR2)2N](-) and [(PPh2)2C5H3](-) and a triphosphenium bromide P(I) precursor result in the formation of phosphorus(I)-containing heterocycles, several of which are of types that have never been prepared before. The methodology described also allows for the preparation of the known heterocycle cyclo-[P(PPh2)N(PPh2)]2 in better yields and purity than the synthetic approach reported previously. Preliminary reactivity studies demonstrate the viability of such zwitterionic oligomers as multidentate ligands for transition metals.

A Comprehensive Investigation of a Zwitterionic GeI Dimer with a 1,2‐Dicationic Core

“…The dative bondingm odel for compounds 1P and 4P has been corroborated through computational and reactivity studies, demonstrating 4P as aP I transfer reagent. [53][54][55][56][57][58][59] Can the same charge transfer that was observed in 1Ge, 1GeCl,a nd 2OTf be spectroscopically verified in 1P and 4P?…”

Synthesis of Heavy Dicyanamide Homologues from Air‐Stable Precursors

“…Schmidpeter had observed early on that cyanide ions displace 1,2‐bis(diphenylphosphino)ethane (dppe) from a triphosphenium cation to form DCP anions in solution using 31 P NMR spectroscopy . Indeed, nucleophilic substitution of the phosphine ligands from triphosphenium cations has been used by our group as a conceptually simple and practical method for the generation of new or useful univalent phosphorus containing molecules and oligomers . Using these results as a basis, we investigated the reactions of [dppeP][Br] and commercial cyanide sources like [K][CN], [Na][CN] and [ n Bu 4 N][CN] in the hopes of finding a safe, straightforward method of synthesizing and isolating DCP salts.…”

“…[32] Indeed, nucleophilic substitution of the phosphinel igandsf rom triphosphenium cations hasb een used by our group as ac onceptually simple and practical method for the generation of new or useful univalent phosphorus containing molecules ando ligomers. [33][34][35][36][37][38] in the hopes of finding as afe, straightforward method of synthesizing and isolatingD CP salts. While in all cases the generation of DCP was confirmed by its distinctive singlet in the 31 PNMR spectrum (ca.…”

Synthesis of bis(trithio)phosphines by oxidative transfer of phosphorus(i)

“…However, in several reports, we have described the facile generation of new molecules containing low-valent phosphorus(I) fragments via the versatile "P + " transfer agent [P I dppe][Br] (Scheme 1) through substitution of the diphenylphosphinoethane (dppe) molecule by a different set of ligands. [22][23][24] This approach has proven to be "P" atom efficient in many cases -the transfer of P I atoms from the starting material is often quantitative -and no unnecessary or unexpected by-products are generated. 25 Scheme 1.…”

“…30 Recent work by Rawson and co-workers has included the investigation of the oxidative addition chemistry of 1,2,5,6-tetrathiocins to zero-valent group 10 metal complexes to afford a range of monometallic metal dithiolate complexes 21 (Scheme 3) as well as dimetallic and hexametallic clusters. 22 The tetrathiocin precursors are readily formed in multi-gram quantities 31 and the oxidative addition chemistry often occurs quantitatively by NMR with recovered crystalline yields up to 89% (Scheme 3).…”