Mono- and dinuclear palladium complexes containing 2-pyridylphosphine ligands, including X-ray characterization of Pd₂I₂(µ-PPh₂py)₂ and a dimethylacetylenedicarboxylate A-frame complex Pd₂Cl₂(µ-Ppy₃)₂(µ-MeO₂C•C=C•CO₂Me); py = 2-pyridyl

Abstract

. Can. J. Chcm. 70, 751 (1992). phosphine]palladium(II) complexes are prepared by metathesis of cis-PdC1,(PPh3-,,py,,), species (n = 1-3) using the appropriate sodium halide; py = 2-pyridyl. NMR spectroscopy, particularly ' 3~{ 1~} , is used to distinguish cis and trans isomers. The dinuclear complexes Pd2X2(k-PPh3-,,py,,),, X = halide, are synthesized via a conproportionation reaction using PdX, (PPh,-,,py,,), and Pd,(dba),; dba = dibenzylideneacetone. Both Pd211(k-PPh,py), and a dimethylacetylenedicarboxylate A-frame complex Pd,Cl2(k-Ppy3),(~-MeO?_C . C=C . C02Me) are characterized crystallographically as head-to-tail isomer:. ' The former crystallizes in the monoclinic space group C 2 / c with a = 30.992(3), b = 18.764(1), c = 13.100(1) A, P = 100.676(5)", and Z = 8; the dcta were refined to R = 0.035 for 5874 reflections withal 2 3u(I). The A-frame compound is triclinic of space group PI with a = 13.545(2), b = 15.064(2), c = 11.991(2) A, a = 1 l1.56(1), P = 95.36(1), y = 97.63(1)", and Z = 2; R = 0.033 from 7128 reflections with I ? 3u(I). The Pd,X2(k-PPhpy,)2 complexes exist as a mixture of diastereomers because of chirality induced at the phosphorus atoms. The Pd,X,(k-Ppy,)? complexes in water generate the [ P~~( H~O )~(~-P P~~) $ + dication, which is isolated as various salts. The mononuclear complexes in water generate aquo and hydroxo species.Key words: dimethylacetylenedicarboxylate adducts, palladium complexes (dinuclear), pyridylphosphines. que l'on a isole sous la forme du plusieurs sels. Dans l'eau, les complexes mononuclCaires fournissent des espkces aquo et hydroxo.Mots cle's : adduits de 1'acCtylknedicarboxylate de dimCthyle, complexes dinucleaires du palladium, pyridylphosphines.[Traduit par la rtdaction]

2-Pyridyl-phosphine and -diphosphine complexes of nickel(0), their reactivity (including aqueous solution chemistry), and some related, incidental methylphosphonium iodides

“…The P-centre in a bridging PN 2 is chiral, and thus 1d should show two d P singlets: one for the (R,R) and (S,S) enantiomers, and one for the (R,S) enantiomers. The lone singlet detected at r.t. is thought to be an averaged signal, as reported for Pd 2 Cl 2 (l-PN 2 ) 2 complexes where two singlets, seen at À20°C, coalesce at r.t. to one [14]. The 1 H NMR spectrum of 1d is complex (Fig.…”

How Changing the Bridgehead Can Affect the Properties of Tripodal Ligands

“…Our initial interest in 1 – 3 focused on the potential structural/functional effects of the increasing Lewis acidity of the bridgehead as Group 15 is descended. At the top of the group (N and P) the higher electronegativity, combined with the presence of compact lone pairs, is known to lead to ambidentate character in which both the N‐atoms of the 2‐py groups and the Group 15 atom (E) can donate to metal ions (Figure b) . However, the onset of electropositive character and relativistic stabilisation of the lone pair at Bi are anticipated to lead to increasing acceptor character for the bridgehead as the group is descended (Figure b) .…”

Preparation and properties of rhodium(I) and iridium(I) diolefin complexes of heterodifunctional phosphorus–imine chelating ligands and a related iminophosphine. 103Rh NMR parameters of the rhodium complexes obtained via indirect two-dimensional 31P, 103Rh{1H} NMR spectroscopy

“…Complexes of this type have been made with monodentate chelating and chiral phosphines and, in many cases, these complexes have been found to be effective catalyst precursors for homogeneous hydrogenation at ambient temperature and pressure (13)(14)(15)(16). Pyridyl phosphines have also been widely used as chelating and bridging ligands for a variety of transition metals including rhodium (17)(18)(19)(20). Also widely known are rhodium complexes derived from chelating phosphine-amine bidentate ligands (21)(22)(23)(24)(25)(26)(27)(28)(29)(30)(31)(32)(33)(34)(35).…”