David M. A. Minahan

Trans chelation in transition-metal complexes: synthesis and characterization of palladium (II) complexes of bis(diphenylarsino) alkanes

Preparation de Ph 2 As(CH 2 ) n AsPh 2 (n=6, 12, 16) et des complexes PdLX 2 (X=Cl, Br, I, CNS; n=6, 8, 10, 12, 16) et PdLCl 2 (n=7, 9, 11). Spectres RMN et IR

REACTIONS OF COORDINATED PHOSPHORUS AND SULFUR LIGANDS

At the start of this Section we would remind readers of a number of excellent review articles and books which give general background to the area covered by this Chapter, viz: a comprehensive survey of P, As, Sb donor chemistry to mid-19721, diphosphine complexes2, an early survey of transition metal complexes,6 fluoralicyclic-P, As complexes,7 phosphite, phosponite and amine-phosphine compounds,8 Lewis base carbonyl complexes,9 reactions of and catalysis by hydrido complexes,10 zerovalent nickel, palladium and platinum complexes,11 cyclophosphines and arsines,12–13 cyclic phosphine complexes,14 olefin — group 5B ligand complexes,15 transition metal cyanide complexes,16 structure of hydride complexes,17 oxidative additions to d8 metal complexes,18 carbene complexes,19 31P nmr spectra of complexes,20 general structure21 and structure of nitrosyl complexes,22,23 reactions of coordinated pnictogens,24 dioxygen complexes,25 open-chain tetradentate26 and tripod tetradentate chelates,27 homogeneous hydrogenations28 and general catalysis,29and a book which acts as a guide to the whole area.30

Unsymmetrical bisphosphorus ligands. Phosphorus-31 and carbon-13 nuclear magnetic resonance and mass spectral measurements

The unsymmetrical bisphosphorus ligands of the type RPhP[CH2]6PPh2(R = Me, Et, and cyclohexyl), R2P[CH2]nPPh2(R = Me and Et, n= 3 and 4), RPhP[CH2]4PPh2(R = Me and Et), and EtPhP[CH2]3PPh2 have been characterized by 31P and 13C n.m.r. spectroscopy and by mass spectral measurements. The variation in the 31P chemical shift is explained in terms of the steric requirements of the substituent groups attached to phosphorus and the 13C n.m.r. of the trimethylene-bridged diphosphines are compared and contrasted with their dimethylene-bridged analogues.

Carbon-13 and phosphorus-31 nuclear magnetic resonance spectra of some symmetrical long chain ditertiary phosphines and the carbon-13 nuclear magnetic resonance spectra of the arsenic analogues

The proton noise decoupled pulsed Fourier transform 13C n.m.r. spectra of the long chain ditertiary phosphines and arsines of the general formula Ph2E[CH2]nEPh2(E = P and As, n= 6–12 and 16) have been examined. The range of significant carbon–phosphorus coupling in the phosphines studied is limited to a maximum of three bonds. The method for assigning each of the individual 13C resonances is discussed and the assignments are contrasted with those obtained for the corresponding linear alkanes. Systematic trends in the chemical shift parameter are observed and are explained in terms of the effect of the presence of phosphorus or arsenic atoms at both ends of the alkane chain. The 31P n.m.r. spectra of the phosphines have also been recorded. The correlation between the 31P chemical shift and the effective steric bulk of the polymethylene backbone has been examined for those ligands and compared to values reported for similar ditertiary phosphines with fewer methylene units present between the phosphorus atoms.