Synthesis, Structural Preference and Catalytic Activity of Neutral and Cationic Methylpalladium(II) Complexes Containing N-Arylpyridine-2-carbaldimine Chelating Ligands

2002 ◽  
Vol 67 (8) ◽  
pp. 1200-1214 ◽  
Author(s):  
Ana Arnaiz ◽  
Gabriel García-Herbosa ◽  
José V. Cuevas ◽  
Olivier Lavastre ◽  
Caroline Hillairet ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Chelating Ligands ◽  
Maximum Hardness ◽  
Neutral Complex ◽  
Synthesis And Crystal Structure ◽  
Square Planar ◽  
Square Planar Complexes ◽  
Alkene Oligomerization ◽  
Maximum Hardness Principle ◽  
Rule Out

The syntheses and structures of neutral complexes [PdCl(Py-2-CH=NAr)(Me)] (Ar = 4-MeC6H4, 4-MeOC6H4, 4-CF3C6H4) and cationic complexes [Pd(Py-2-CH=NAr)(Me)(MeCN)]SbF6 (Ar = 4-MeC6H4, 4-MeOC6H4, 4-CF3C6H4) are described. The preference for the trans-isomers in the cationic complexes and for the cis-isomers in the neutral complexes is discussed on the basis of electronic arguments and supported by DFT calculations. The observed preference seems to follow the maximum hardness principle (MHP) introduced by Pearson. On the basis of the application of this principle to square planar complexes of palladium(II) and platinum(II) we propose the trans choice, which means that the hardest ligand arranges trans to the softest one. The synthesis and crystal structure of the related neutral complex trans-[Pd(CF3COO)(Py-2-CH=NC6H4-4-OMe)(Me)] is also described and allows to rule out the charge of the complex as the cause of isomeric preference. We also report our preliminary studies dealing with the catalytic activity of the cationic complexes in alkene oligomerization and copolymerization with CO.

Synthesis, structural characterization and catalytic activity of chlororuthenium(II) complexes with substituted Schiff base/phosphine ancillary ligands

2020 ◽  
Vol 75 (9-10) ◽  
pp. 851-857
Author(s):  
Chong Chen ◽  
Fule Wu ◽  
Jiao Ji ◽  
Ai-Quan Jia ◽  
Qian-Feng Zhang
Keyword(s):  
Schiff Base ◽  
Catalytic Activity ◽  
Structural Characterization ◽  
Room Temperature ◽  
Molecular Structures ◽  
Cationic Complex ◽  
Neutral Complex ◽  
Ancillary Ligands ◽  
X Ray ◽  
X Ray Crystallography

AbstractTreatment of [(η6-p-cymene)RuCl2]2 with one equivalent of chlorodiphenylphosphine in tetrahydrofuran at reflux afforded a neutral complex [(η6-p-cymene)RuCl2(κ1-P-PPh2OH)] (1). Similarly, the reaction of [Ru(bpy)2Cl2·2H2O] (bpy = 2,2′-bipyridine) and chlorodiphenylphosphine in methanol gave a cationic complex [Ru(bpy)2Cl(κ1-P-PPh2OCH3)](PF6) (2), while treatment of [RuCl2(PPh3)3] with [2-(C5H4N)CH=N(CH2)2N(CH3)2] (L1) in tetrahydrofuran at room temperature afforded a ruthenium(II) complex [Ru(PPh3)Cl2(κ3-N,N,N-L1)] (3). Interaction of the chloro-bridged complex [Ru(CO)2Cl2]n with one equivalent of [Ph2P(o-C6H4)CH=N(CH2)2N(CH3)2] (L2) led to the isolation of [Ru(CO)Cl2(κ3-P,N,N-L2)] (4). The molecular structures of the ruthenium(II) complexes 1–4 have been determined by single-crystal X-ray crystallography. The properties of the ruthenium(II) complex 4 as a hydrogenation catalyst for acetophenone were also tested.

Synthesis and crystal structure analyses of tri-substituted guanidine-based copper(II) complexes

2021 ◽  
Vol 76 (3-4) ◽  
pp. 193-199
Author(s):  
Muhammad Said ◽  
Sadia Rehman ◽  
Muhammad Ikram ◽  
Hizbullah Khan ◽  
Carola Schulzke
Keyword(s):  
Crystal Structure ◽  
Solid State ◽  
Molecular Structures ◽  
Hydroxyl Groups ◽  
Synthesis And Crystal Structure ◽  
Pyramidal Geometry ◽  
Tautomeric Forms ◽  
Square Planar ◽  
Nitrogen Donor ◽  
Square Pyramidal Geometry

Abstract Three guanidine-derived tri-substituted ligands viz. N-pivaloyl-N′,N″-bis-(2-methoxyphenyl)guanidine (L1), N-pivaloyl-N′-(2-methoxyphenyl)-N″-phenylguanidine (L2) and N-pivaloyl-N′-(2-methoxyphenyl)-N″-(2-tolyl)guanidine (L3) were reacted with Cu(II) acetate to produce the corresponding complexes. The significance of the substituent on N″ for the resulting molecular structures and their packing in the solid state has been studied with respect to the structural specifics of the corresponding Cu(II) complexes. The key characteristic of the guanidine-based metal complexation with Cu(II) is the formation of an essentially square planar core with an N2O2 donor set. As an exception, in the complex of L1, the substituent’s methoxy moiety also interacts with the Cu(II) center to generate a square-pyramidal geometry. The hydroxyl groups of the imidic acid tautomeric forms of L1–L3, in addition to N″, are also bonded to Cu(II) in all three complexes rather than the nitrogen donor of the guanidine motif.

Chlorine nuclear quadrupole resonance in some chloro complexes of divalent copper

1971 ◽  
Vol 24 (10) ◽  
pp. 1993 ◽  
Author(s):  
DE Scaife
Keyword(s):  
Nuclear Quadrupole Resonance ◽  
Covalent Bonding ◽  
Divalent Copper ◽  
Chloro Complexes ◽  
35Cl Nucleus ◽  
Square Planar ◽  
Bonding Interaction ◽  
Quadrupole Resonance ◽  
Square Planar Complexes ◽  
Nuclear Quadrupole

Nuclear quadrupole resonance for the 35Cl nucleus has been observed in some chloro complexes of divalent copper. Square-planar complexes each show two resonance lines, with the following frequencies (at 77�K): (CH3NH3)2CuCl4, 10.780, 12.157 MHz; (C2H5NH3)2CuCl4, 10.817, 12.074 MHz; (enH2)CuCl4, 10.271, 11.901 MHz; and (C3H7NH3)2CuCl4 at 223�K, 11.290 and 11.781 MHz. NH4CuCl3, containing dimeric Cu2Cl62- units, has resonances, at 77�K, at 11.907, 11.993, and 12.448 MHz. The trigonal pyramidal anion in Co(NH3)6CuCl5 has two resonances at 9.642 and 10.352 MHz at 77�K. ��� These results are compared with previous results for copper chloro complexes, and the implications of covalent bonding are discussed. In particular, it is suggested that the long-bond interaction between units in square-planar complexes amounts to 7-16% of the bonding interaction within the units.

Extended X-ray absorption fine structure and multiple-scattering simulation of nickel dithiolene complexes Ni[S2C2(CF3)2]2n(n= −2, −1, 0) and an olefin adduct Ni[S2C2(CF3)2]2(1-hexene)

2015 ◽  
Vol 22 (1) ◽  
pp. 124-129 ◽  
Author(s):  
Weiwei Gu ◽  
Hongxin Wang ◽  
Kun Wang
Keyword(s):  
Fine Structure ◽  
Multiple Scattering ◽  
Edge Structure ◽  
X Ray ◽  
Absorption Fine ◽  
Square Planar ◽  
Square Planar Complexes ◽  
Uv Visible ◽  
Edge Features ◽  
X Ray Absorption

A series of Ni dithiolene complexes Ni[S2C2(CF3)]2n(n= −2, −1, 0) (1,2,3) and a 1-hexene adduct Ni[S2C2(CF3)2]2(C6H12) (4) have been examined by NiK-edge X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine-structure (EXAFS) spectroscopies. Ni XANES for1–3reveals clear pre-edge features and approximately +0.7 eV shift in the NiK-edge position for `one-electron' oxidation. EXAFS simulation shows that the Ni—S bond distances for1,2and3(2.11–2.16 Å) are within the typical values for square planar complexes and decrease by ∼0.022 Å for each `one-electron' oxidation. The changes in NiK-edge energy positions and Ni—S distances are consistent with the `non-innocent' character of the dithiolene ligand. The Ni—C interactions at ∼3.0 Å are analyzed and the multiple-scattering parameters are also determined, leading to a better simulation for the overall EXAFS spectra. The 1-hexene adduct4presents no pre-edge feature, and its NiK-edge position shifts by −0.8 eV in comparison with its starting dithiolene complex3. Consistently, EXAFS also showed that the Ni—S distances in4elongate by ∼0.046 Å in comparison with3. The evidence confirms that the neutral complex is `reduced' upon addition of olefin, presumably by olefin donating the π-electron density to the LUMO of3as suggested by UV/visible spectroscopy in the literature.

scholarly journals Synthesis and crystal structure of [Pd{C6H4(CH2NHCH2Ph)-2-κ2C,N}(μ-I)]2

2017 ◽  
Vol 73 (11) ◽  
pp. 1612-1615
Author(s):  
Delia Bautista ◽  
Sergio J. Benitez-Benitez
Keyword(s):  
Crystal Structure ◽  
Significant Influence ◽  
Title Complex ◽  
Asymmetric Unit ◽  
Coordination Environment ◽  
Synthesis And Crystal Structure ◽  
Square Planar ◽  
Intermolecular Contacts ◽  
Type C ◽  
Methyl Phenyl

The binuclear title complex, di-μ-iodido-bis({2-[(benzylamino-κN)methyl]phenyl-κC1}palladium(II)), [Pd2I2(C14H14N)2], was prepared by reaction of [Pd{C6H4(CH2NHCH2Ph)-2}(μ-OAc)]2with NaI. It crystallizes with one discrete molecule in the asymmetric unit. The molecule presents an iodide-bridged dimeric structure with acisoidarrangement with respect to theC,N-cyclopalladated ligands. Both PdIIatoms have a slightly distorted square-planar coordination environment. Weak intermolecular contacts of the type C—H...Pd seem to have a significant influence on the arrangement of the molecules along thebaxis in the crystal.

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