Synthesis and comparative chemistry of the early-late transition metal heterobimetallacycles CpCp′Ta(CH2)2Ir(CO)(L) and their main-group element-late transition metal analogues R2P(CH2)2Ir(CO)(L)

Catalytic Fluorination of Boron Compounds at a Bismuth Redox Platform

10.26434/chemrxiv.9729143 ◽

2019 ◽

Author(s):

Oriol Planas ◽

Feng Wang ◽

Markus Leutzsch ◽

Josep Cornella

Keyword(s):

Transition Metal ◽

Main Group ◽

Group Element ◽

Oxidation States ◽

Boron Compounds ◽

Main Text ◽

Main Group Element ◽

Rational Ligand Design ◽

Supplementary Material

The ability of bismuth to maneuver between different oxidation states in a catalytic redox cycle, mimicking the canonical organometallic steps associated to a transition metal, is an elusive and unprecedented approach in the field of homogeneous catalysis. Herein we present a catalytic protocol based on bismuth, a benign and sustainable main-group element, capable of performing every organometallic step in the context of oxidative fluorination of boron compounds; a territory reserved to transition metals. A rational ligand design featuring hypervalent coordination together with a mechanistic understanding of the fundamental steps, permitted a catalytic fluorination protocol based on a Bi(III)/Bi(V) redox couple, which represents a unique example where a main-group element is capable of outperforming its transition metal counterparts.<br>A main text and supplementary material have been attached as pdf files containing all the methodology, techniques and characterization of the compounds reported.<br>

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On the Coordination Role of Pyridyl-Nitrogen in the Structural Chemistry of Pyridyl-Substituted Dithiocarbamate Ligands

Crystals ◽

10.3390/cryst11030286 ◽

2021 ◽

Vol 11 (3) ◽

pp. 286

Author(s):

Edward R.T. Tiekink

Keyword(s):

Transition Metal ◽

Main Group ◽

Group Element ◽

Systematic Research ◽

Pyridyl Nitrogen ◽

General Observation ◽

Supramolecular Architectures ◽

Main Group Element ◽

Metal Dithiocarbamates

A search of the Cambridge Structural Database was conducted for pyridyl-substituted dithiocarbamate ligands. This entailed molecules containing both an NCS2− residue and pyridyl group(s), in order to study their complexation behavior in their transition metal and main group element crystals, i.e., d- and p-block elements. In all, 73 different structures were identified with 30 distinct dithiocarbamate ligands. As a general observation, the structures of the transition metal dithiocarbamates resembled those of their non-pyridyl derivatives, there being no role for the pyridyl-nitrogen atom in coordination. While the same is true for many main group element dithiocarbamates, a far greater role for coordination of the pyridyl-nitrogen atoms was evident, in particular, for the heavier elements. The participation of pyridyl-nitrogen in coordination often leads to the formation of dimeric aggregates but also one-dimensional chains and two-dimensional arrays. Capricious behaviour in closely related species that adopted very different architectures is noted. Sometimes different molecules comprising the asymmetric-unit of a crystal behave differently. The foregoing suggests this to be an area in early development and is a fertile avenue for systematic research for probing further crystallization outcomes and for the rational generation of supramolecular architectures.

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Heterobimetallic early–late transition-metal tetrameric metallomacrocycles via self assembly

Chemical Communications ◽

10.1039/a604842k ◽

1997 ◽

pp. 77-78 ◽

Cited By ~ 23

Author(s):

Peter J. Stang ◽

Neal E. Persky

Keyword(s):

Transition Metal ◽

Self Assembly ◽

Late Transition Metal ◽

Late Transition ◽

Early Late

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Fragility of Metallic Glass Forming Liquids

MRS Proceedings ◽

10.1557/proc-754-cc5.9 ◽

2002 ◽

Vol 754 ◽

Cited By ~ 1

Author(s):

G. J. Fan ◽

R. K. Wunderlich ◽

H.-J. Fecht

Keyword(s):

Transition Metal ◽

Metallic Glass ◽

Liquid Structure ◽

Energy Difference ◽

Late Transition Metal ◽

Glass Forming ◽

Metal Type ◽

Gibbs Free Energy Difference ◽

Late Transition ◽

Early Late

ABSTRACTBased on the available kinetic and thermodynamic data, we compare the kinetic fragility and thermodynamic fragility of different metallic glass forming liquids. The results indicate a correlation between the kinetic and thermodynamic fragility in metallic glass forming liquids, consistent with the energy landscape model which predicts a connection between the kinetic and thermodynamic properties of supercooled liquids. The metal - metalloid glass forming alloys such as PdNiCuP are found to exhibit a distinctively different correlation as compared to early – late transition metal – type metallic glass forming alloys such as ZrTiCuNiBe. For the same thermodynamic fragility the former exhibit a much larger kinetic fragility indicating that the two classes of alloys have a different liquid structure. In addition, the relationship between the kinetic fragility and the Gibbs free energy difference between the undercooled liquid and the crystalline phases has been discussed in both metal metalloid glass forming alloys and early - late transition metal – type metallic glass forming alloys.

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