Syntheses and structures of metal cyanamide compounds

This thesis describes syntheses and structures of some metal cyanamide compounds, based on "soft cations" of metal elements. In PbNCN, the cyanamide anion exhibits two different C-N bond lengths. Quantum-chemical DFT calculations prove that the cyanamide anion is comparatively easy to distort. Two modification of mercury cyanamide has been synthesized by controlling the pH value. The X-ray analysis shows that Hg atoms and the one end of NCN units form zigzag chains in HgNCN(II), and two C-N bond lengths are significantly different. In HgNCN(I) NCN unit bonds to Hg atoms from the both sides and the two C-N bond lenghs are almost identical. The crystal structures of Hg2(NCN)Cl2 and Hg3(NCN)2Cl2 show that there are sharing edged 20-membered rings formed by [Hg3(NCN)2]2+ as a backbone, but the cavities of the rings are very flexible. Ag2NCN, as an example of a transition metal cyanamide, shows that NCN unit has mixed character of "N=C=N" and "N?C-N". The structure of Ag(H4N4C2)3NO3 shows that two dicyandiamides behave as a mono-dentate ligand through nitrile nitrogen atoms and the third dicyandiamide locates just in the vacant site binding by hydrogen bonds. In Ni(NCNH2)4Cl2, Co(NCNH2)4Cl2 and Cu(NCNH2)4Cl2, Ni2+, Co2+ or Cu2+ are octahedrally coordinated by four equatorial H2NCN molecules and two axial chloride ions. Ni(NCNH2)4Cl2/ Co(NCNH2)4Cl2 are Curie paramagnets with two/three unpaired electrons.

Grantor dc:publisher

Publikationsserver der RWTH Aachen University

Year dc:date

2002

Author dc:creator

• Liu, Xiaohui

Contributors dc:contributor

• Dronskowski, Richard

• info:eu-repo/classification/ddc/540
• Chemie
• Metal Cyanamide

Statement dc:rights

• info:eu-repo/semantics/openAccess

Language dc:language

eng

Identifier

https://publications.rwth-aachen.de/search?p=id:%22RWTH-CONV-119232%22

OAI identifier oai:identifier

oai:publications.rwth-aachen.de:57167