Single-Crystal to Single-Crystal Reversible Transformations Induced by Thermal Dehydration in Keggin-Type Polyoxometalates Decorated with Copper(II)-Picolinate Complexes: The Structure Directing Role of Guanidinium

Three new hybrid inorganic-metalorganic compounds containing Keggin-type polyoxometalates, neutral copper(II)-picolinate complexes and guanidinium cations have been synthesized in bench conditions and characterized by elemental analysis, infrared spectroscopy and single-crystal X-ray diffraction:...

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Main Authors: Aroa Pache, Santiago Reinoso, Leire San Felices, Amaia Iturrospe, Luis Lezama, Juan M. Gutiérrez-Zorrilla
Format: Article
Language:English
Published: MDPI AG 2015-05-01
Series:Inorganics
Subjects:
Online Access:http://www.mdpi.com/2304-6740/3/2/194
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author Aroa Pache
Santiago Reinoso
Leire San Felices
Amaia Iturrospe
Luis Lezama
Juan M. Gutiérrez-Zorrilla
author_facet Aroa Pache
Santiago Reinoso
Leire San Felices
Amaia Iturrospe
Luis Lezama
Juan M. Gutiérrez-Zorrilla
author_sort Aroa Pache
collection DOAJ
description Three new hybrid inorganic-metalorganic compounds containing Keggin-type polyoxometalates, neutral copper(II)-picolinate complexes and guanidinium cations have been synthesized in bench conditions and characterized by elemental analysis, infrared spectroscopy and single-crystal X-ray diffraction: the isostructural [C(NH2)3]4[{XW12O40}{Cu2(pic)4}]·[Cu2(pic)4(H2O)]2·6H2O [X = Si (1), Ge (3)] and [C(NH2)3]8[{SiW12O40}2{Cu(pic)2}3{Cu2(pic)4(H2O)}2]·8H2O (2). The three compounds show a pronounced two-dimensional character owing to the structure-directing role of guanidinium. In 1 and 3, layers of [{XW12O40}{Cu2(pic)4}]n4n− hybrid POM chains and layers of [Cu2(pic)4(H2O)] complexes and [C(NH2)3]+ cations pack alternately along the z axis. The hydrogen-bonding network established by guanidinium leads to a trihexagonal tiling arrangement of all copper(II)-picolinate species. In contrast, layers of [C(NH2)3]+-linked [{SiW12O40}2{Cu(pic)2}3]n8n− double chains where each Keggin cluster displays a {Cu2(pic)4(H2O)} moiety pointing at the intralamellar space are observed in 2. The thermal stability of 1–3 has been studied by thermogravimetric analyses and variable temperature powder X-ray diffraction. Compounds 1 and 3 undergo single-crystal to single-crystal transformations promoted by reversible dehydration processes and the structures of the corresponding anhydrous phases 1a and 3a have been established. Despite the fact that the [Cu2(pic)4(H2O)] dimeric complexes split into [Cu(pic)2] monomers upon dehydration, the packing remains almost unaltered thanks to the preservation of the hydrogen-bonding network established by guanidinium and its associated Kagome-type lattice. Splitting of the dimeric complexes has been correlated with the electron paramagnetic resonance spectra.
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spelling doaj.art-6df9f361ec3a4202a3a6847645b1a8fa2022-12-21T22:39:00ZengMDPI AGInorganics2304-67402015-05-013219421810.3390/inorganics3020194inorganics3020194Single-Crystal to Single-Crystal Reversible Transformations Induced by Thermal Dehydration in Keggin-Type Polyoxometalates Decorated with Copper(II)-Picolinate Complexes: The Structure Directing Role of GuanidiniumAroa Pache0Santiago Reinoso1Leire San Felices2Amaia Iturrospe3Luis Lezama4Juan M. Gutiérrez-Zorrilla5Departamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco UPV/EHU, P. O. Box 644, Bilbao 48080, SpainDepartamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco UPV/EHU, P. O. Box 644, Bilbao 48080, SpainServicios Generales de Investigación SGIker, Universidad del País Vasco UPV/EHU, P. O. Box 644, Bilbao 48080, SpainDepartamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco UPV/EHU, P. O. Box 644, Bilbao 48080, SpainDepartamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco UPV/EHU, P. O. Box 644, Bilbao 48080, SpainDepartamento de Química Inorgánica, Facultad de Ciencia y Tecnología, Universidad del País Vasco UPV/EHU, P. O. Box 644, Bilbao 48080, SpainThree new hybrid inorganic-metalorganic compounds containing Keggin-type polyoxometalates, neutral copper(II)-picolinate complexes and guanidinium cations have been synthesized in bench conditions and characterized by elemental analysis, infrared spectroscopy and single-crystal X-ray diffraction: the isostructural [C(NH2)3]4[{XW12O40}{Cu2(pic)4}]·[Cu2(pic)4(H2O)]2·6H2O [X = Si (1), Ge (3)] and [C(NH2)3]8[{SiW12O40}2{Cu(pic)2}3{Cu2(pic)4(H2O)}2]·8H2O (2). The three compounds show a pronounced two-dimensional character owing to the structure-directing role of guanidinium. In 1 and 3, layers of [{XW12O40}{Cu2(pic)4}]n4n− hybrid POM chains and layers of [Cu2(pic)4(H2O)] complexes and [C(NH2)3]+ cations pack alternately along the z axis. The hydrogen-bonding network established by guanidinium leads to a trihexagonal tiling arrangement of all copper(II)-picolinate species. In contrast, layers of [C(NH2)3]+-linked [{SiW12O40}2{Cu(pic)2}3]n8n− double chains where each Keggin cluster displays a {Cu2(pic)4(H2O)} moiety pointing at the intralamellar space are observed in 2. The thermal stability of 1–3 has been studied by thermogravimetric analyses and variable temperature powder X-ray diffraction. Compounds 1 and 3 undergo single-crystal to single-crystal transformations promoted by reversible dehydration processes and the structures of the corresponding anhydrous phases 1a and 3a have been established. Despite the fact that the [Cu2(pic)4(H2O)] dimeric complexes split into [Cu(pic)2] monomers upon dehydration, the packing remains almost unaltered thanks to the preservation of the hydrogen-bonding network established by guanidinium and its associated Kagome-type lattice. Splitting of the dimeric complexes has been correlated with the electron paramagnetic resonance spectra.http://www.mdpi.com/2304-6740/3/2/194polyoxometalatescrystal-to-crystal transformationsguanidinium
spellingShingle Aroa Pache
Santiago Reinoso
Leire San Felices
Amaia Iturrospe
Luis Lezama
Juan M. Gutiérrez-Zorrilla
Single-Crystal to Single-Crystal Reversible Transformations Induced by Thermal Dehydration in Keggin-Type Polyoxometalates Decorated with Copper(II)-Picolinate Complexes: The Structure Directing Role of Guanidinium
Inorganics
polyoxometalates
crystal-to-crystal transformations
guanidinium
title Single-Crystal to Single-Crystal Reversible Transformations Induced by Thermal Dehydration in Keggin-Type Polyoxometalates Decorated with Copper(II)-Picolinate Complexes: The Structure Directing Role of Guanidinium
title_full Single-Crystal to Single-Crystal Reversible Transformations Induced by Thermal Dehydration in Keggin-Type Polyoxometalates Decorated with Copper(II)-Picolinate Complexes: The Structure Directing Role of Guanidinium
title_fullStr Single-Crystal to Single-Crystal Reversible Transformations Induced by Thermal Dehydration in Keggin-Type Polyoxometalates Decorated with Copper(II)-Picolinate Complexes: The Structure Directing Role of Guanidinium
title_full_unstemmed Single-Crystal to Single-Crystal Reversible Transformations Induced by Thermal Dehydration in Keggin-Type Polyoxometalates Decorated with Copper(II)-Picolinate Complexes: The Structure Directing Role of Guanidinium
title_short Single-Crystal to Single-Crystal Reversible Transformations Induced by Thermal Dehydration in Keggin-Type Polyoxometalates Decorated with Copper(II)-Picolinate Complexes: The Structure Directing Role of Guanidinium
title_sort single crystal to single crystal reversible transformations induced by thermal dehydration in keggin type polyoxometalates decorated with copper ii picolinate complexes the structure directing role of guanidinium
topic polyoxometalates
crystal-to-crystal transformations
guanidinium
url http://www.mdpi.com/2304-6740/3/2/194
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