Direct coordination of a germanium(ii) dicationic center to transition metals

2017 ◽  
Vol 53 (9) ◽  
pp. 1467-1469 ◽  
Author(s):  
Ravindra K. Raut ◽  
Moumita Majumdar

A group 14 E(ii) dicationic center effortlessly coordinates to transition metal centers, demonstrating as an efficient cationic ligand.

2020 ◽  
pp. 43-49

The synthesis of bis(arylimino)pyridine complexes of seven different transition metals and their applications after activation with methylaluminoxane (MAO) in homogeneous olefin dimerization and oligomerization reactions is described. The synthesis of bis(arylimino)pyridine ligand precursors was achieved via condensation reactions of 2,6-diacetylpyridine with different substituted anilines. The bis(arylimino)pyridine compounds were reacted with 3d transition metal halides of the metals Ti, V, Cr, Mn, Fe, Ni and Co to give the corresponding mono-ligated complexes. Among a series of complexes with varying metal centers, but containing the same ligand, the bis(arylimino)pyridine iron(III) complex provided the best results for the dimerization of 1-hexene after activation with MAO. Beside linear products, methyl branched olefins were detected as well. For all product compositions, a marginal higher amount of hexene dimers was observed, e.g. the insertion of 1-hexene proceeds slightly faster than the insertion of 1-pentene.


2021 ◽  
Author(s):  
Daniyal Kiani ◽  
Sagar Sourav ◽  
Yadan Tang ◽  
Jonas Baltrusaitis ◽  
Israel E. Wachs

The literature on methane dehydroaromatization (MDA) to benzene using ZSM-5 supported, group V–VIII transition metal-based catalysts (MOx/ZSM-5) is critically reviewed with a focus on in situ and operando molecular insights.


2018 ◽  
Author(s):  
Srimanta Pakhira ◽  
Jose Mendoza-Cortes

<div>Covalent organic frameworks (COFs) have emerged as an important class of nano-porous crystalline materials with many potential applications. They are intriguing platforms for the design of porous skeletons with special functionality at the molecular level. However, despite their extraordinary properties, it is difficult to control their electronic properties, thus hindering the potential implementation in electronic devices. A new form of nanoporous material, COFs intercalated with first row transition metal is proposed to address this fundamental drawback - the lack of electronic tunability. Using first-principles calculations, we have designed 31 new COF materials <i>in-silico</i> by intercalating all of the first row transition metals (TMs) with boroxine-linked and triazine-linked COFs: COF-TM-x (where TM=Sc-Zn and x=3-5). This is a significant addition considering that only 187 experimentally COFs structures has been reported and characterized so far. We have investigated their structure and electronic properties. Specifically, we predict that COF's band gap and density of states (DOSs) can be controlled by intercalating first row transition metal atoms (TM: Sc - Zn) and fine tuned by the concentration of TMs. We also found that the $d$-subshell electron density of the TMs plays the main role in determining the electronic properties of the COFs. Thus intercalated-COFs provide a new strategy to control the electronic properties of materials within a porous network. This work opens up new avenues for the design of TM-intercalated materials with promising future applications in nanoporous electronic devices, where a high surface area coupled with fine-tuned electronic properties are desired.</div>


Author(s):  
Olivier Charles Gagné ◽  
Frank Christopher Hawthorne

Bond-length distributions are examined for thirty-three configurations of the metalloid ions and fifty-six configurations of the post-transition-metal ions bonded to oxygen. Lone-pair stereoactivity is discussed.


Author(s):  
Olivier Charles Gagné ◽  
Frank Christopher Hawthorne

Bond-length distributions are examined for thirty-three configurations of the metalloid ions and fifty-six configurations of the post-transition-metal ions bonded to oxygen. Lone-pair stereoactivity is discussed.


Doklady BGUIR ◽  
2020 ◽  
Vol 18 (7) ◽  
pp. 87-95
Author(s):  
M. S. Baranava ◽  
P. A. Praskurava

The search for fundamental physical laws which lead to stable high-temperature ferromagnetism is an urgent task. In addition to the already synthesized two-dimensional materials, there remains a wide list of possible structures, the stability of which is predicted theoretically. The article suggests the results of studying the electronic properties of MAX3 (M = Cr, Fe, A = Ge, Si, X = S, Se, Te) transition metals based compounds with nanostructured magnetism. The research was carried out using quantum mechanical simulation in specialized VASP software and calculations within the Heisenberg model. The ground magnetic states of twodimensional MAX3 and the corresponding energy band structures are determined. We found that among the systems under study, CrGeTe3 is a semiconductor nanosized ferromagnet. In addition, one is a semiconductor with a bandgap of 0.35 eV. Other materials are antiferromagnetic. The magnetic moment in MAX3 is localized on the transition metal atoms: in particular, the main one on the d-orbital of the transition metal atom (and only a small part on the p-orbital of the chalcogen). For CrGeTe3, the exchange interaction integral is calculated. The mechanisms of the formation of magnetic order was established. According to the obtained exchange interaction integrals, a strong ferromagnetic order is formed in the semiconductor plane. The distribution of the projection density of electronic states indicates hybridization between the d-orbital of the transition metal atom and the p-orbital of the chalcogen. The study revealed that the exchange interaction by the mechanism of superexchange is more probabilistic.


2021 ◽  
Author(s):  
Yingqiu Gu ◽  
Di Xu ◽  
Yun Huang ◽  
Zhouyang Long ◽  
Guojian Chen

Transition metals have been considered as potential catalysts for ammonia decomposition to produce COx-free hydrogen for fuel cells. However, the facile synthesis of transition metal catalyst with small size active...


ACS Omega ◽  
2020 ◽  
Vol 5 (33) ◽  
pp. 21271-21287
Author(s):  
Huynh Thi Phuong Loan ◽  
Thanh Q. Bui ◽  
Tran Thi Ai My ◽  
Nguyen Thi Thanh Hai ◽  
Duong Tuan Quang ◽  
...  

2021 ◽  
Author(s):  
Sujoy Rana ◽  
Jyoti Prasad Biswas ◽  
Sabarni Paul ◽  
Aniruddha Paik ◽  
Debabrata Maiti

The promising aspects of iron in synthetic chemistry are being explored for three-four decades as a green and eco-friendly alternative to late transition metals. This present review unveils these rich iron-chemistry towards different transformations.


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