Major Differences Between Mononuclear and Binuclear Manganese Carbonyl Cyanides and Isoelectronic Binary Chromium Carbonyls Arising from Basicity of the Cyanide Nitrogen Atom

2014 ◽  
Vol 67 (9) ◽  
pp. 1318 ◽  
Author(s):  
Ruixue Jia ◽  
Chaoyang Wang ◽  
Luo Qiong ◽  
Qian-Shu Li ◽  
Yaoming Xie ◽  
...  

The manganese carbonyl cyanides Mn(CO)n(CN) and Mn2(CO)n(CN)2 have been investigated by density functional theory. The lowest energy structure for Mn(CO)5(CN) is found to be the experimentally known C-bonded cyanide. The experimentally unknown N-bonded Mn(CO)5(NC) lies ~60 kJ mol–1 above its cyanide isomer. The Mn(CO)4(CN) isomers are obtained by removal of a CO group in various ways from Mn(CO)5(CN) or Mn(CO)5(NC). Three structures, cyanide Mn(CO)3(CN), isocyanide Mn(CO)3(NC), and Mn(CO)3(η2-CN), are found for the tricarbonyl. All low-energy binuclear Mn2(CO)n(CN)2 structures have two end-to-end bridging CN groups. These two η2-CN bridges can be oriented in the same or opposite directions. The Mn2(CO)7(CN)2 structures of this type can be derived from these Mn2(CO)8(CN)2 structures by removal of a CO group with relatively little change in the remainder of the structure. These low-energy Mn2(CO)n(CN)2 structures (n = 8, 7) are very different from the previously studied isoelectronic Cr2(CO)n+2 structures in which low-energy end-to-end CO bridged structures are not found.

RSC Advances ◽  
2015 ◽  
Vol 5 (70) ◽  
pp. 56885-56890 ◽  
Author(s):  
Amr A. A. Attia ◽  
Alexandru Lupan ◽  
R. Bruce King

The structures and energetics of the cobaltaazaboranes CpCoNHBn−2Hn−2 (n = 8 to 12) have been investigated by density functional theory. Degree 3 vertices are found for the nitrogen atoms in low-energy 8- and 9-vertex structures.


RSC Advances ◽  
2021 ◽  
Vol 11 (15) ◽  
pp. 8654-8663
Author(s):  
Fatima Zahra Ramadan ◽  
Flaviano José dos Santos ◽  
Lalla Btissam Drissi ◽  
Samir Lounis

Based on density functional theory combined with low-energy models, we explore the magnetic properties of a hybrid atomic-thick two-dimensional (2D) material made of germanene doped with fluorine atoms in a half-fluorinated configuration (Ge2F).


2016 ◽  
Vol 858 ◽  
pp. 1125-1128
Author(s):  
Ioannis Deretzis ◽  
Filippo Giannazzo ◽  
Antonino La Magna

Notwithstanding the graphitization of SiC under high thermal treatment can take place for all SiC surfaces, the quality of the resulting graphene as well as its structural and electrical characteristics strongly depend on the SiC face where growth has taken place. In this paper we use the density functional theory to analyze the structural and electronic properties of epitaxial graphene grown on three different SiC planes. Calculations are presented for the (6√3×6√3)R30°-reconstructed SiC(0001) surface (Si face) as well as the nonpolar SiC(11-20) and SiC(1-100) planes. We argue that the formation of a strongly-bound interface buffer layer is an exclusive property of the SiC(0001) surface. Moreover, our results indicate that nonpolar planes give rise to graphene with a nearly ideal low-energy spectrum.


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