Fluxional behaviour of potentially bidentate phenanthroline, naphthyridine, and phthalazine ligands in palladium complexes

1978 ◽  
Vol 56 (7) ◽  
pp. 950-953 ◽  
Author(s):  
J. Bradley Brandon ◽  
Michael Collins ◽  
Keith R. Dixon
Keyword(s):  
Nmr Spectra ◽  
Variable Temperature ◽  
Palladium Complexes ◽  
Exchange Mechanism ◽  
Heterocyclic Ligands ◽  
Planar Structures ◽  
Square Planar ◽  
Intramolecular Process

The synthesis of a series of palladium complexes, cis-[PdCl(PEt3)2L][Y]; L = 1,10-phenanthroline, 1,8-naphthyridine, or phthalazine; Y = BF4− or ClO4−; is reported. Variable temperature 1H and 31P nmr spectra are discussed in terms of square planar structures in which the heterocyclic ligands are essentially monodentate and fluxional with the palladium exchanging between the two nitrogen atoms. Above ca. −10 °C a dissociative exchange mechanism operates in all three complexes and, when L = 1,10-phenanthroline or 1,8-naphthyridine, exchange continues at lower temperatures by an intramolecular process.

scholarly journals Synthesis of N,O-Chelating Hydrazidopalladium Complexes from 1,2-Bis(trifluoroacetyl)hydrazine

Inorganics ◽  
2021 ◽  
Vol 9 (10) ◽  
pp. 76
Author(s):  
Yoshihito Kayaki ◽  
Tomohiro Hayakawa ◽  
Takao Ikariya
Keyword(s):  
Crystal Structure ◽  
Structure Determination ◽  
Nmr Spectra ◽  
Structural Changes ◽  
Variable Temperature ◽  
Palladium Complexes ◽  
Electron Donors ◽  
Crystal Structure Determination ◽  
X Ray ◽  
Square Planar

N,O-chelating dicarbonylhydrazido-palladium complexes were synthesized by treatment of 1,2-bis(trifluoroacetyl)hydrazine with a mixture of a Pd(0) source, [Pd(dba)2] (DBA = dibenzylideneacetone), and four-electron donors including 1,3-bis(diphenylphosphino)propane (DPPP), N,N,N’,N’-tetramethylethylenediamine (TMEDA), and two equivalents of triphenylphosphine. The same products from DPPP and TMEDA could be obtained alternatively by using Pd(OAc)2 through deprotonation of the diacylhydrazine. The five-membered chelate structure was confirmed by NMR spectra and X-ray crystal structure determination. The X-ray structures indicate that the products are formally considered as Pd(II) complexes with a hydrazido(2–) ligand. In the case of the triphenylphosphine-coordinated complex, a fluxional behavior in dichloromethane-d2 was observed by variable temperature NMR experiments, possibly due to structural changes between the square planar and pseudo-tetrahedral geometries.

scholarly journals [AU(DIEN)Cl]Cl2: Exchange Phenomena Observed by H1 and C13 NMR Spectroscopy

1999 ◽  
Vol 6 (4-5) ◽  
pp. 261-269 ◽  
Author(s):  
Sabine L. Best ◽  
Zijian Guo ◽  
Milos I. Djuran ◽  
Peter J. Sadler
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Variable Temperature ◽  
Hydroxo Complex ◽  
Acidic Solutions ◽  
Exchange Effects ◽  
Square Planar ◽  
Ph Range ◽  
Solution Behaviour

The solution behaviour of the square-planar gold(III) complex [Au(dien)Cl]Cl2 (dien = 1,5- diamino-3-azapentane) was investigated by H1 and C13 NMR spectroscopy. We have found that H1 NMR spectra of [Au(dien)Cl]Cl2 are characterised by exchange behaviour over the whole pH range, and some exchange effects are also seen in C13 NMR spectra of the deprotonated hydroxo derivative of the complex in alkaline solution. An exchange rate of > 378 s-1 was determined from H1 NMR spectra at pH∗2 (coalescence temperature 40C° ). In slightly acidic solutions of the complex, H1 chemical shifts are in accordance with the known deprotonation of the central amine group of the complexed diethylenetriamine ligand. In C13 NMR spectra, two separate sets of resonances are observed for the chloro and the hydroxo complex of gold(III) diethylenetriamine. The hydroxo complex [Au(dien-H)OH]+ shows exchange effects in C13 NMR spectra. Variable temperature studies show the carbon atoms next to the central secondary amine to be inequivalent and each present in two different environments that are in intermediate to fast exchange on the NMR time-scale.

ChemInform Abstract: Comparison of Variable-Temperature 1H NMR Spectra of Five-Coordinate High-Spin (S = 5/2) Iron(III) Porphyrins and Chlorins

ChemInform ◽  
1988 ◽  
Vol 19 (36) ◽  
Author(s):  
M. J. PAWLIK ◽  
P. K. MILLER ◽  
E. P. JUN. SULLIVAN ◽  
M. A. LEVSTIK ◽  
D. A. ALMOND ◽  
...  
Keyword(s):  
1H Nmr ◽  
High Spin ◽  
Nmr Spectra ◽  
Variable Temperature ◽  
1H Nmr Spectra

Synthesis, structural and magnetic properties of macrocyclic aza-amido binuclear copper(II) complexes

1989 ◽  
Vol 67 (4) ◽  
pp. 662-670 ◽  
Author(s):  
Sanat K. Mandal ◽  
Laurence K. Thompson ◽  
Michael J. Newlands ◽  
Amal K. Biswas ◽  
Bibhutosh Adhikary ◽  
...  
Keyword(s):  
Variable Temperature ◽  
Complex Iii ◽  
Azomethine Nitrogen ◽  
X Ray Diffraction ◽  
Binuclear Copper ◽  
Magnetic Studies ◽  
Monoclinic System ◽  
Space Group ◽  
Pyramidal Geometry ◽  
Square Planar

Binuclear, antiferromagnetically coupled, macrocyclic copper(II) complexes, [Cu2(C28H32N4O4)]•H2O (II) and [Cu2(C36H32N4O4)]•CH3CN•H2O (III), involving asymmetric ligands with two deprotonated amide, two azomethine nitrogen, and two phenoxide donors at the binuclear centre, have been synthesized and characterized by single-crystal X-ray diffraction and variable temperature magnetic studies. Complex II crystallizes in the monoclinic system, space group P21/n, with a = 16.4854(9) Å, b = 7.6005(13) Å, c = 21.1617(11) Å, β = 104.090(5)°, Z = 4, Rf = 0.068 for 2062 significant reflections. The two copper(II) centres have square planar N2O2 donor sets with two phenoxide oxygen atoms bridging the copper centres with a copper–copper separation of 2.898(2) Å. A long copper–oxygen (amide) contact (2.808(10) Å) forms a weak dimer association. Complex III crystallizes in the triclinic system, space group [Formula: see text], with a = 8.7771(9) Å, b = 12.3983(16) Å, c = 15.7299(16) Å, α = 85.003(11)°, β = 84.574(8)°, γ = 76.838(10)°, Z = 2, Rf = 0.041 for 2966 significant reflections. The two copper(II) centres have distorted square-pyramidal geometry involving an N2O2 in plane donor set and two phenoxide oxygen bridges with a copper–copper separation of 3.018(1) Å. The fifth coordination site at each copper centre involves an amide oxygen from a neighbouring molecule (Cu(1)—O 2.371(4), Cu(2)—O 2.413(3) Å) in a staggered intermolecular array. Very strong antiferromagnetic exchange is observed in both cases (−2J = 689 ± 7 cm−1 (II), −2J = 816 ± 8 cm−1 (III)). Keywords: macrocycles, binuclear copper(II) complexes.

X-ray Structure and Variable Temperature NMR Spectra of [meso-Triarylcorrolato]copper(III)

2003 ◽  
Vol 42 (15) ◽  
pp. 4495-4497 ◽  
Author(s):  
Christian Brückner ◽  
Raymond P. Briñas ◽  
Jeanette A. Krause Bauer
Keyword(s):  
Nmr Spectra ◽  
Variable Temperature ◽  
X Ray ◽  
Variable Temperature Nmr Spectra

Exchange reactions by NMR without variable temperature. An experiment using allyl-palladium complexes

1978 ◽  
Vol 55 (2) ◽  
pp. 131 ◽  
Author(s):  
Trevor G. Appleton ◽  
John D. Cotton
Keyword(s):  
Variable Temperature ◽  
Palladium Complexes ◽  
Exchange Reactions

Palladium complexes with the tripodal phosphine tris-(2-diphenylphosphinoethyl)amine. Synthesis and structure of trigonal, tetrahedral, trigonal bipyramidal, and square planar complexes

1989 ◽  
pp. 211 ◽  
Author(s):  
Franco Cecconi ◽  
Carlo A. Ghilardi ◽  
Stefano Midollini ◽  
Simonetta Moneti ◽  
Annabella Orlandini ◽  
...  
Keyword(s):  
Palladium Complexes ◽  
Trigonal Bipyramidal ◽  
Square Planar ◽  
Square Planar Complexes

Sealed capsules for convenient acquisition of variable-temperature controlled-atmosphere magic-angle-spinning NMR spectra of solids

1986 ◽  
Vol 68 (3) ◽  
pp. 561-563 ◽  
Author(s):  
T Adrian Carpenter ◽  
Jacek Klinowski ◽  
D Tilak ◽  
B Tennakoon ◽  
Cyril J Smith ◽  
...  
Keyword(s):  
Nmr Spectra ◽  
Variable Temperature ◽  
Magic Angle Spinning ◽  
Magic Angle ◽  
Controlled Atmosphere ◽  
Temperature Controlled ◽  
Angle Spinning

Crystal structure, and variable temperature proton and carbon-13 NMR spectra of the 9-membered ring complex [Cr(CO)4{E,Z-PPh2CH2C(tBu)NNC(tBu)CH2PPh2}]

1993 ◽  
Vol 462 (1-2) ◽  
pp. 221-224 ◽  
Author(s):  
Sarath D. Perera ◽  
Bernard L. Shaw ◽  
Mark Thornton-Pett ◽  
Jonathan D. Vessey
Keyword(s):  
Crystal Structure ◽  
Nmr Spectra ◽  
Variable Temperature ◽  
Membered Ring ◽  
Ring Complex
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