The Structure and Reactivity of Some Amino Phosphines

Sim, William (1968) The Structure and Reactivity of Some Amino Phosphines. PhD thesis, University of Glasgow.

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The aminophosphines, have been prepared by the following reaction scheme: (1) PhPCl2 + 4RNH2 → PhP(NHR)2 + 2RNH3+Cl (2) 2PhPCl2 + PhP(NHR)2 + 2Et3N → PhP(NR. PPh2)2 + 2Et3NH+Cl- Using n-pentane as solvent, greatly improved yields of the intermediates PhP(NHR) , where R = Me and Et, have been obtained. Reaction of (I) and (II) with excess methyl iodide in ether yields only a mono-adduct in each case, quaternisation occurring at a terminal phosphorus atom. In the absence of ether, there is evidence for further quaternisation but the ease of hydrolysis of the products has precluded satisfactory analyses. The stepwise addition of sulphur to (I) has resulted in the isolation of only the di- and the trisulphides, the structure of the disulphide having been shown by 1H n. m. r. spectroscopy to be: Sulphuration of II proceeds initially at a terminal phosphorus atom but the structure of the disulphide has not been well established. Both (I) and (II) readily replace three molar equivalents of carbon monoxide in their reactions with Group VIb carbonyls. The products have been shown by infra-red spectroscopy to be the cis-trisubstituted complexes. A 1H n. m. r. investigation into the source of magnetic nonequivalence of the isopropyl-methyl protons in the series of compounds, PhP(NHPir) X, where X = nothing, O, S, Se and Mel, indicates a relationship between the magnitude of nonequivalence and the rate of proton exchange at nitrogen. This, in turn, appears to affect the rate of inversion at the nitrogen atoms. In the same series of compounds, a relationship appears to exist between the chemical shift of the ortho-protons of the phenyl group and the effective positive charge on phosphorus. Reference is made here to the 1H n. m. r. spectra of a variety of aminophosphines prepared in the course of this work. The mass spectral cracking patterns of a variety of methyl substituted aminophosphines have been elucidated. The high relative abundance of ions which retain the P-N unit is attributed to resonance stabilisation involving structures of the following type: +/-P-N ↔ -P=N+.

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Keywords: Inorganic chemistry, Physical chemistry
Date of Award: 1968
Depositing User: Enlighten Team
Unique ID: glathesis:1968-78474
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 30 Jan 2020 15:16
Last Modified: 30 Jan 2020 15:16

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