Crystal structure and spectroscopic behavior of synthetic novgorodovaite Ca2(C2O4)Cl2·2Hs2O and its twinned triclinic heptahydrate analog

Synthetic novgorodovaite analog Ca2( C2O4) Cl2·2H2O is identical to its natural counterpart. It crystallizes in the monoclinic I2/m space group with a = 6.9352(3), b = 7.3800(4), c = 7.4426(3) Å, β = 94.303(4)°, V = 379.85(3) Å3 and Z = 2. The heptahydrate analog, Ca2( C2O4)Cl2·7H2O, crystallizes as...

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Autores principales:	Piro, Oscar Enrique, Echeverría, Gustavo Alberto, González Baró, Ana Cecilia, Baran, Enrique José
Formato:	Articulo
Lenguaje:	Inglés
Publicado:	2017
Materias:	Química Synthetic novgorodovaite Heptahydrate analog Single-crystal X-ray structure Powder X-ray diffraction Vibrational spectra
Acceso en línea:	http://sedici.unlp.edu.ar/handle/10915/118671
Aporte de:	SEDICI (UNLP) de Universidad Nacional de La Plata

id	I19-R120-10915-118671
record_format	dspace
institution	Universidad Nacional de La Plata
institution_str	I-19
repository_str	R-120
collection	SEDICI (UNLP)
language	Inglés
topic	Química Synthetic novgorodovaite Heptahydrate analog Single-crystal X-ray structure Powder X-ray diffraction Vibrational spectra
spellingShingle	Química Synthetic novgorodovaite Heptahydrate analog Single-crystal X-ray structure Powder X-ray diffraction Vibrational spectra Piro, Oscar Enrique Echeverría, Gustavo Alberto González Baró, Ana Cecilia Baran, Enrique José Crystal structure and spectroscopic behavior of synthetic novgorodovaite Ca<SUB>2</SUB>(C<SUB>2</SUB>O<SUB>4</SUB>)Cl<SUB>2</SUB>·<SUB>2</SUB>Hs<SUB>2</SUB>O and its twinned triclinic heptahydrate analog
topic_facet	Química Synthetic novgorodovaite Heptahydrate analog Single-crystal X-ray structure Powder X-ray diffraction Vibrational spectra
description	Synthetic novgorodovaite analog Ca2( C2O4) Cl2·2H2O is identical to its natural counterpart. It crystallizes in the monoclinic I2/m space group with a = 6.9352(3), b = 7.3800(4), c = 7.4426(3) Å, β = 94.303(4)°, V = 379.85(3) Å3 and Z = 2. The heptahydrate analog, Ca2( C2O4)Cl2·7H2O, crystallizes as triclinic twins in the P1 space group with a = 7.3928(8), b = 8.9925(4), c = 10.484(2) Å, α = 84.070(7), β = 70.95(1), γ = 88.545(7)°, V = 655.3(1) Å3 and Z = 2. The crystal packing of both calcium oxalate–chloride double salts favors the directional bonding of oxalate, C2O4 2−, ligands to calcium ions as do other related calcium oxalate minerals. The π-bonding between C and O atoms of the C2O4 2− oxalate group leaves sp2-hydridised orbitals of the oxygen atoms available for bonding to Ca. Thus, the Ca–O bonds in both calcium oxalate–chloride double salts are directed so as to lie in the plane of the oxalate group. This behavior is reinforced by the short O···O distances between the oxygens attached to a given carbon atom, which favors them bonding to a shared Ca atom in bidentate fashion. Strong bonding in the plane of the oxalate anion and wide spacing perpendicular to that plane due to repulsion between oxalate π-electron clouds gives rise to a polymerized structural units which are common to both hydrates, explaining the nearly equal cell constants ~7.4 Å which are defined by the periodicity of Ca-oxalate chains in the framework (monoclinic b ≈ triclinic a). When compared with novgorodovaite, the higher water content of Ca2( C2O4) Cl2·7H2O leads to some major differences in their structures and ensuing physical properties. While novgorodovaite has a three-dimensional framework structure, in the higher hydrate, the highly polar water molecules displace chloride ions from the calcium coordination sphere and surround them through OwH···Cl hydrogen bonds. As a result, polymerization in Ca2(C2O4)Cl2·7H2O solid is limited to the formation of two-dimensional Ca2( C2O4)(H2O)5 slabs parallel to (001), inter-layered with hydrated chloride anions. This layered structure accounts for (001) being both a perfect cleavage and a twin interface plane. The infrared and Raman spectra of both salts are also briefly discussed.
format	Articulo Articulo
author	Piro, Oscar Enrique Echeverría, Gustavo Alberto González Baró, Ana Cecilia Baran, Enrique José
author_facet	Piro, Oscar Enrique Echeverría, Gustavo Alberto González Baró, Ana Cecilia Baran, Enrique José
author_sort	Piro, Oscar Enrique
title	Crystal structure and spectroscopic behavior of synthetic novgorodovaite Ca<SUB>2</SUB>(C<SUB>2</SUB>O<SUB>4</SUB>)Cl<SUB>2</SUB>·<SUB>2</SUB>Hs<SUB>2</SUB>O and its twinned triclinic heptahydrate analog
title_short	Crystal structure and spectroscopic behavior of synthetic novgorodovaite Ca<SUB>2</SUB>(C<SUB>2</SUB>O<SUB>4</SUB>)Cl<SUB>2</SUB>·<SUB>2</SUB>Hs<SUB>2</SUB>O and its twinned triclinic heptahydrate analog
title_full	Crystal structure and spectroscopic behavior of synthetic novgorodovaite Ca<SUB>2</SUB>(C<SUB>2</SUB>O<SUB>4</SUB>)Cl<SUB>2</SUB>·<SUB>2</SUB>Hs<SUB>2</SUB>O and its twinned triclinic heptahydrate analog
title_fullStr	Crystal structure and spectroscopic behavior of synthetic novgorodovaite Ca<SUB>2</SUB>(C<SUB>2</SUB>O<SUB>4</SUB>)Cl<SUB>2</SUB>·<SUB>2</SUB>Hs<SUB>2</SUB>O and its twinned triclinic heptahydrate analog
title_full_unstemmed	Crystal structure and spectroscopic behavior of synthetic novgorodovaite Ca<SUB>2</SUB>(C<SUB>2</SUB>O<SUB>4</SUB>)Cl<SUB>2</SUB>·<SUB>2</SUB>Hs<SUB>2</SUB>O and its twinned triclinic heptahydrate analog
title_sort	crystal structure and spectroscopic behavior of synthetic novgorodovaite ca<sub>2</sub>(c<sub>2</sub>o<sub>4</sub>)cl<sub>2</sub>·<sub>2</sub>hs<sub>2</sub>o and its twinned triclinic heptahydrate analog
publishDate	2017
url	http://sedici.unlp.edu.ar/handle/10915/118671
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bdutipo_str	Repositorios
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Crystal structure and spectroscopic behavior of synthetic novgorodovaite Ca<SUB>2</SUB>(C<SUB>2</SUB>O<SUB>4</SUB>)Cl<SUB>2</SUB>·<SUB>2</SUB>Hs<SUB>2</SUB>O and its twinned triclinic heptahydrate analog

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