Search results for "ligandi"

Synthesis, Spectroscopic, and Structural Investigation of the Cyclic [N(PR2E)2]+ Cations (E = Se, Te; R = iPr, Ph): the Effect of Anion and R-Group E…

2006

Two-electron oxidation of the [N(PiPr2E)2]- anion with iodine produces the cyclic [N(PiPr2E)2]+ (E = Se, Te) cations, which exhibit long E−E bonds in the iodide salts [N(PiPr2Se)2]I (4) and [N(PiPr2Te)2]I (5). The iodide salts 4 and 5 are converted to the ion-separated salts [N(PiPr2Se)2]SbF6 (6) and [N(PiPr2Te)2]SbF6 (7) upon treatment with AgSbF6. Compounds 4−7 were characterized in solution by multinuclear NMR, vibrational, and UV−visible spectroscopy supported by DFT calculations. A structural comparison of salts 4−7 and [N(PiPr2Te)2]Cl (8) confirms that the long E−E bonds in 4, 5, and 8 can be attributed primarily to the donation of electron density from a lone pair of the halide count…

New tellurium-containing ring systems

2007

The recent discovery of a suitable synthesis of the monoanionic ditelluroimidodiphosphinate ligands [TePR2NPR2Te]− (R = Ph, iPr, tBu) has facilitated investigations of the fundamental chemistry of these chelating inorganic ligands. This article is focused on aspects of that chemistry in which the behaviour of this ditelluro PNP ligand differs from that of the well-studied dithio and diseleno congeners. The emphasis is on new tellurium-containing ring systems formed in: (a) redox transformations and (b) the synthesis of metal complexes. peerReviewed

Synthesis of a labile sulfur-centred ligand, [S(H)C(PPh2S)2]-: structural diversity in lithium(i), zinc(ii) and nickel(ii) complexes

2016

A high-yield synthesis of [Li{S(H)C(PPh2S)2}]2 [Li2·(3)2] was developed and this reagent was used in metathesis with ZnCl2 and NiCl2 to produce homoleptic complexes 4 and 5b in 85 and 93% yields, respectively. The solid-state structure of the octahedral complex [Zn{S(H)C(PPh2S)2}2] (4) reveals notable inequivalence between the Zn–S(C) and Zn–S(P) contacts (2.274(1) Å vs. 2.842(1) and 2.884(1) Å, respectively). Two structural isomers of the homoleptic complex [Ni{S(H)C(PPh2S)2}2] were isolated after prolonged crystallization processes. The octahedral green Ni(II) isomer 5a exhibits the two monoprotonated ligands bonded in a tridentate (S,S′,S′′) mode to the Ni(II) centre with three distinctl…

A Practical Perspective : The Effect of Ligand Conformers on the Negative Image-Based Screening

2019

Negative image-based (NIB) screening is a rigid molecular docking methodology that can also be employed in docking rescoring. During the NIB screening, a negative image is generated based on the target protein’s ligand-binding cavity by inverting its shape and electrostatics. The resulting NIB model is a drug-like entity or pseudo-ligand that is compared directly against ligand 3D conformers, as is done with a template compound in the ligand-based screening. This cavity-based rigid docking has been demonstrated to work with genuine drug targets in both benchmark testing and drug candidate/lead discovery. Firstly, the study explores in-depth the applicability of different ligand 3D conformer…

Multivalent N-donor ligands for the construction of coordination polymers and coordination polymer gels

2018

This work describes the synthesis and characterisation of several multivalent N-donor ligands and their coordination compounds and the use of these ligands in the construction of coordination polymers and coordination polymer gels. The project can be divided into two parts. The first part of the research is focused on the coordination chemistry of ring-substituted biimidazoles in acidic media. The dependence of the formation of ion pairs and zwitterionic, especially zinc and copper containing coordination compounds on the pH of the reaction medium and ring-substituents of the ligand were examined. The second part of the study deals with the preparation of Ag, Zn and Cu coordination polymers…

Synthesis, Reactivity, and Computational Analysis of Halophosphines Supported by Dianionic Guanidinate Ligands

2012

The reported chemistry and reactivity of guanidinate supported group 15 elements in the +3 oxidation state, particularly phosphorus, is limited when compared to their ubiquity in supporting metallic elements across the periodic table. We have synthesized a series of chlorophosphines utilizing homo- and heteroleptic (dianionic)guanidinates and have completed a comprehensive study of their reactivity. Most notable is the reluctancy of these four-membered rings to form the corresponding N-heterocyclic phosphenium cations, the tendency to chemically and thermally eliminate carbodiimide, and the scarcely observed ring expansion by insertion of a chloro(imino)phosphine into a P–N bond of the P–N–…

Experimental and Theoretical Investigations of the Redox Behavior of the Heterodichalcogenido Ligands [(EPiPr2)(TePiPr2)N]− (E = S, Se): Cyclic Catio…

2008

The two-electron oxidation of the lithium salts of the heterodichalcogenidoimidodiphosphinate anions [(EPiPr2)(TePiPr2)N]− (1a, E = S; 1b, E = Se) with iodine yields cyclic cations [(EPiPr2)(TePiPr2)N]+ as their iodide salts [(SPiPr2)(TePiPr2)N]I (2a) and [(SePiPr2)(TePiPr2)N]I (2b). The five-membered rings in 2a and 2b both display an elongated E−Te bond as a consequence of an interaction between tellurium and the iodide anion. One-electron reduction of 2a and 2b with cobaltocene produces the neutral dimers (EPiPr2NPiPr2Te−)2 (3a, E = S; 3b, E = Se), which are connected exclusively through a Te−Te bond. Two-electron reduction of 2a and 2b with 2 equiv of cobaltocene regenerates the corresp…

Structural studies on filamin domain interactions

2015

Asymmetric [N–I–N]+halonium complexes in solution?

2020

Assessment of the solution equilibria of [bis(pyridine)iodine(I)]+ complexes by ESI-MS and NMR reveals the preference of iodine(I) to form complexes with a more basic pyridine. Mixtures of symmetric [bis(pyridine)iodine(I)]+ complexes undergo statistical ligand exchange, with a predominant entropic driving force favoring asymmetric systems. The influence of ligand basicity, concentration, temperature, and ligand composition is evaluated. Our findings are expected to facilitate the investigations, and the supramolecular and synthetic applications of halonium ions’ halogen bonds. peerReviewed

Ligand exchange among iodine(I) complexes

2022

A detailed investigation of ligand exchange between iodine(I) ions in [N⋯I⋯N]+ halogen-bonded complexes is presented. Ligand exchange reactions were conducted to successfully confirm whether iodine(I) complex formation, via the classical [N⋯Ag⋯N]+ to [N⋯I⋯N]+ cation exchange reaction from their analogous Ag+ complexes, could be determined solely by using 1H NMR spectroscopy. In instances where the formation of the iodine(I) complex was unclear or in low yield by the traditional cation exchange reaction, a ligand exchange reaction was used to form the desired iodine(I) complexes in a quantitative manner. Mixing two homoleptic [N⋯I⋯N]+ iodine(I) complexes in 1 : 1 ratio was found to undergo a…