scholarly journals Halogen Bonding Involving I2 and d8 Transition-Metal Pincer Complexes

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 373
Author(s):  
Marek Freindorf ◽  
Seth Yannacone ◽  
Vytor Oliveira ◽  
Niraj Verma ◽  
Elfi Kraka
Keyword(s):  
Charge Transfer ◽  
Transition Metal ◽  
Bond Strength ◽  
Oxidative Addition ◽  
Halogen Bonding ◽  
Mode Analysis ◽  
Pincer Complexes ◽  
Local Mode ◽  
Electronic Effects ◽  
Pincer Complex

We systematically investigated iodine–metal and iodine–iodine bonding in van Koten’s pincer complex and 19 modifications changing substituents and/or the transition metal with a PBE0–D3(BJ)/aug–cc–pVTZ/PP(M,I) model chemistry. As a novel tool for the quantitative assessment of the iodine–metal and iodine–iodine bond strength in these complexes we used the local mode analysis, originally introduced by Konkoli and Cremer, complemented with NBO and Bader’s QTAIM analyses. Our study reveals the major electronic effects in the catalytic activity of the M–I–I non-classical three-center bond of the pincer complex, which is involved in the oxidative addition of molecular iodine I2 to the metal center. According to our investigations the charge transfer from the metal to the σ* antibonding orbital of the I–I bond changes the 3c–4e character of the M–I–I three-center bond, which leads to weakening of the iodine I–I bond and strengthening of the metal–iodine M–I bond, facilitating in this way the oxidative addition of I2 to the metal. The charge transfer can be systematically modified by substitution at different places of the pincer complex and by different transition metals, changing the strength of both the M–I and the I2 bonds. We also modeled for the original pincer complex how solvents with different polarity influence the 3c–4e character of the M–I–I bond. Our results provide new guidelines for the design of pincer complexes with specific iodine–metal bond strengths and introduce the local vibrational mode analysis as an efficient tool to assess the bond strength in complexes.

scholarly journals Characterizing the interplay of Pauli repulsion, electrostatics, dispersion and charge transfer in halogen bonding with energy decomposition analysis

2018 ◽  
Vol 20 (2) ◽  
pp. 905-915 ◽  
Author(s):  
Jonathan Thirman ◽  
Elric Engelage ◽  
Stefan M. Huber ◽  
Martin Head-Gordon
Keyword(s):  
Charge Transfer ◽  
Bond Strength ◽  
Halogen Bond ◽  
Decomposition Analysis ◽  
Halogen Bonding ◽  
Energy Decomposition Analysis ◽  
Energy Decomposition ◽  
Pauli Repulsion

Variational energy decomposition analysis establishes charge-transfer as the origin of halogen bond strength differences that go against electrostatics.

scholarly journals Metal–Halogen Bonding Seen through the Eyes of Vibrational Spectroscopy

Materials ◽  
2019 ◽  
Vol 13 (1) ◽  
pp. 55 ◽  
Author(s):  
Vytor P. Oliveira ◽  
Bruna L. Marcial ◽  
Francisco B. C. Machado ◽  
Elfi Kraka
Keyword(s):  
Density Functional ◽  
Halogen Bonding ◽  
Fine Tuning ◽  
Mode Analysis ◽  
Planar Geometry ◽  
Local Mode ◽  
Special Role ◽  
Bonded Materials ◽  
Local Vibrational Mode ◽  
Donor And Acceptor

Incorporation of a metal center into halogen-bonded materials can efficiently fine-tune the strength of the halogen bonds and introduce new electronic functionalities. The metal atom can adopt two possible roles: serving as halogen acceptor or polarizing the halogen donor and acceptor groups. We investigated both scenarios for 23 metal–halogen dimers trans-M(Y2)(NC5H4X-3)2 with M = Pd(II), Pt(II); Y = F, Cl, Br; X = Cl, Br, I; and NC5H4X-3 = 3-halopyridine. As a new tool for the quantitative assessment of metal–halogen bonding, we introduced our local vibrational mode analysis, complemented by energy and electron density analyses and electrostatic potential studies at the density functional theory (DFT) and coupled-cluster single, double, and perturbative triple excitations (CCSD(T)) levels of theory. We could for the first time quantify the various attractive contacts and their contribution to the dimer stability and clarify the special role of halogen bonding in these systems. The largest contribution to the stability of the dimers is either due to halogen bonding or nonspecific interactions. Hydrogen bonding plays only a secondary role. The metal can only act as halogen acceptor when the monomer adopts a (quasi-)planar geometry. The best strategy to accomplish this is to substitute the halo-pyridine ring with a halo-diazole ring, which considerably strengthens halogen bonding. Our findings based on the local mode analysis provide a solid platform for fine-tuning of existing and for design of new metal–halogen-bonded materials.

scholarly journals Electronic Effects At Interfaces In Cu (cr, mo, w, ta, re) Multilayers

1998 ◽  
Vol 524 ◽  
Author(s):  
A. F. Bello ◽  
T. Van Buuren ◽  
J. E. Klepeis ◽  
T. W. Barbee
Keyword(s):  
Charge Transfer ◽  
Transition Metal ◽  
Metallic Multilayers ◽  
Electronic Effects ◽  
White Line ◽  
Enhanced Absorption ◽  
Absorption Energy ◽  
A Charge ◽  
X Ray Absorption ◽  
Metal Layers

ABSTRACTInterfacial electronic effects between Cu and the transition metals Cr, Mo, W, Ta, Re, are investigated by determining the strength of the white line absorption resonances on the L3,2 edges of Cu in Cu5/TM5 multilayers. X-ray absorption (XAS) was performed to study the white lines, which are directly related to the unoccupied states of Cu in the multilayers. The metallic multilayers are 2 nm in period and 200 nm in total thickness. Each period contains 5 monolayers of Cu and 5 monolayers of the transition metal: = 40% of the atoms are at interfaces. These material pairs form ideal structures for the investigation of interfacial electronic effects as they form no compounds and exhibit terminal solid solubility. Only weak white lines are observed on the L3,2 edges of Cu since all the d-orbitals are filled. In the Cu/TM multilayers, however, we observed enhancement of the Cu white lines. We attribute this to the charge transfer from the “interfacial Cu atoms” d-orbital to the transition metal layers. Analysis of the white line enhancement enables calculation of the charge transfer calculation from the Cu to the transition metal. Cu shows a charge transfer of about 0.03 electrons/interfacial Cu atom in Cu/Cr, 0.064 in Cu/Mo, 0.35 in Cu/Ta, 0.17 in Cu/W , and 0.23 in Cu/Re. This charge transfer is consistent with the enhanced absorption energy of Cu on these materials as observed in thermal desorption experiments.

scholarly journals Synthetic access to a phosphorescent non-palindromic pincer complex of palladium by a double oxidative addition – comproportionation sequence

2020 ◽  
Vol 56 (83) ◽  
pp. 12589-12592
Author(s):  
Wolfram Feuerstein ◽  
Frank Breher
Keyword(s):  
Palladium Complex ◽  
Oxidative Addition ◽  
Pincer Complexes ◽  
New Approach ◽  
Pincer Complex

A highly phosphorescent non-palindromic (C^C^N) palladium complex may be prepared by means of a double oxidative addition – comproportionation sequence, which is a new approach for the synthesis of non-palindromic pincer complexes.

DFT modelling of a diphosphane − N-heterocyclic carbene–Rh(i) pincer complex rearrangement: a computational evaluation of the electronic effects in C–P bond activation

2018 ◽  
Vol 47 (8) ◽  
pp. 2662-2669 ◽  
Author(s):  
H.-L. Qin ◽  
J. Leng ◽  
W. Zhang ◽  
E. A. B. Kantchev
Keyword(s):  
Dft Calculations ◽  
Bond Activation ◽  
Oxidative Addition ◽  
Reductive Elimination ◽  
Electronic Effects ◽  
Complex Rearrangement ◽  
Rate Determining Step ◽  
Computational Evaluation ◽  
Pincer Complex ◽  
Dft Modelling

DFT calculations confirmed that the rearrangement of a PCP-Rh-H pincer to a CCP-Rh-phosphane pincer occured by C–P oxidative addition (ΔG‡ = 29.5 kcal mol−1, rate-determining step), followed by P–H reductive elimination (ΔG‡ = 4.8 kcal mol−1).

Some Problems in the Oxidative Addition and Binding of an Ethylene to a Transition Metal Center.

1987 ◽  
Vol 6 (4) ◽  
pp. 902-902
Author(s):  
Jerome Silestre ◽  
Maria Calhorda ◽  
Roald Hoffman ◽  
Page Stoutland ◽  
Robert Bergman
Keyword(s):  
Transition Metal ◽  
Oxidative Addition ◽  
Metal Center

High resolution spectroscopic study of H2 Se (40+,0) A1 and (40-,0) B2 stretching states: normal mode and local mode analysis

1997 ◽  
Vol 92 (6) ◽  
pp. 1073-1082 ◽  
Author(s):  
By ZE-YI ZHOU ◽  
XIAO-GANG WANG ◽  
ZHONG-PING ZHOU ◽  
OLEG N. ULENIKOV ◽  
GALINA A. ONOPENKO ◽  
...  
Keyword(s):  
High Resolution ◽  
Spectroscopic Study ◽  
Normal Mode ◽  
Mode Analysis ◽  
Local Mode ◽  
Local Mode Analysis
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