Universität zu Köln

Wegner, Susann, Rutz, Christina, Schutte, Kai, Barthel, Juri, Bushmelev, Alexey, Schmidt, Annette ORCID: 0000-0002-7284-7847, Dilchert, Katharina, Fischer, Roland A. and Janiak, Christoph ORCID: 0000-0002-6288-9605 (2017). Soft, Wet-Chemical Synthesis of Metastable Superparamagnetic Hexagonal Close-Packed Nickel Nanoparticles in Different Ionic Liquids. Chem.-Eur. J., 23 (26). S. 6330 - 6341. WEINHEIM: WILEY-V C H VERLAG GMBH. ISSN 1521-3765

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Abstract

The microwave-induced decomposition of bis{N,N-diisopropylacetamidinate}nickel(II) [Ni{MeC(NiPr)(2)}(2)] or bis(1,5-cyclooctadiene)nickel(0) [Ni(COD)(2)] in imidazolium-, pyridinium-, or thiophenium-based ionic liquids (ILs) with different anions (tetrafluoroborate, [BF4](-), hexafluorophosphate, [PF6](-), and bis(trifluoromethylsulfonyl)imide, [NTf2](-)) yields small, uniform nickel nanoparticles (Ni NPs), which are stable in the absence of capping ligands (surfactants) for more than eight weeks. The soft, wet-chemical synthesis yields the metastable Ni hexagonal close-packed (hcp) and not the stable Ni face-centered cubic (fcc) phase. The size of the nickel nanoparticles increases with the molecular volume of the used anions from about 5nm for [BF4](-) to approximate to 10nm for [NTf2](-) (with 1-alkyl-3-methyl-imidazolium cations). The n-butyl-pyridinium, [BPy](+), cation ILs reproducibly yield very small nickel nanoparticles of 2(+/- 1)nm average diameter. The Ni NPs were characterized by high-resolution transmission electron microscopy (HR-TEM) and powder X-ray diffraction. An X-ray photoelectron spectroscopic (XPS) analysis shows an increase of the binding energy (E-B) of the electron from the Ni2p(3/2) orbital of the very small 2(+/- 1)nm diameter Ni particles by about 0.3eV to E-B=853.2eV compared with bulk Ni-0, which is traced to the small cluster size. The Ni nanoparticles show superparamagnetic behavior from 150K up to room temperature. The saturation magnetization of a Ni (2 +/- 1nm) sample from [BPy][NTf2] is 2.08Am(2)kg(-1) and of a Ni (10 +/- 4nm) sample from [LMIm][NTf2] it is 0.99Am(2)kg(-1), ([LMIm]=1-lauryl-3-methyl- imidazolium). The Ni NPs were active catalysts in IL dispersions for 1-hexene or benzene hydrogenation. Over 90% conversion was reached under 5bar H-2 in 1h at 100 degrees C for 1-hexene and a turnover frequency (TOF) up to 1330mol(hexane)(mol(Ni))(-1)h(-1) or in 60h at 100 degrees C for benzene hydrogenation and TOF=23mol(cyclohexane)(mol(Ni))(-1)h(-1).

Item Type:	Journal Article
Creators:	Creators Email ORCID ORCID Put Code Wegner, Susann UNSPECIFIED UNSPECIFIED UNSPECIFIED Rutz, Christina UNSPECIFIED UNSPECIFIED UNSPECIFIED Schutte, Kai UNSPECIFIED UNSPECIFIED UNSPECIFIED Barthel, Juri UNSPECIFIED UNSPECIFIED UNSPECIFIED Bushmelev, Alexey UNSPECIFIED UNSPECIFIED UNSPECIFIED Schmidt, Annette UNSPECIFIED orcid.org/0000-0002-7284-7847 UNSPECIFIED Dilchert, Katharina UNSPECIFIED UNSPECIFIED UNSPECIFIED Fischer, Roland A. UNSPECIFIED UNSPECIFIED UNSPECIFIED Janiak, Christoph UNSPECIFIED orcid.org/0000-0002-6288-9605 UNSPECIFIED
URN:	urn:nbn:de:hbz:38-231320
DOI:	10.1002/chem.201605251
Journal or Publication Title:	Chem.-Eur. J.
Volume:	23
Number:	26
Page Range:	S. 6330 - 6341
Date:	2017
Publisher:	WILEY-V C H VERLAG GMBH
Place of Publication:	WEINHEIM
ISSN:	1521-3765
Language:	English
Faculty:	Unspecified
Divisions:	Unspecified
Subjects:	no entry
Uncontrolled Keywords:	Keywords Language TRANSITION-METAL NANOPARTICLES; SIZE-DEPENDENT FORMATION; RUTHENIUM NANOPARTICLES; MAGNETIC-PROPERTIES; GOLD NANOPARTICLES; ORGANOMETALLIC PRECURSORS; IRIDIUM NANOPARTICLES; IONOTHERMAL SYNTHESIS; RECYCLABLE CATALYSTS; CONVENIENT SYNTHESIS Multiple languages Chemistry, Multidisciplinary Multiple languages
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/23132