[en] A series of iron(II) chloride complexes of pentadentate ligands related to α,α,α’,α’-tetra(pyrazolyl)-2,6-lutidine, pz4lut, has been prepared to evaluate whether pyrazolyl substitution has any systematic impact on the electronic properties of the complexes. For this purpose, the new tetrakis(3,4,5-trimethylpyrazolyl)lutidine ligand, pz**4lut, was prepared via a CoCl2-catalyzed rearrangement reaction. The equimolar combination of ligand and FeCl2 in methanol gives the appropriate 1:1 complexes [FeCl(pzR4lut)]Cl that are each isolated in the solid state as a hygroscopic solvate. In solution, the iron(II) complexes have been fully characterized by several spectroscopic methods and cyclic voltammetry. In the solid state, the complexes have been characterized by X-ray diffraction, magnetic measurements and, in some cases, by Mössbauer spectroscopy. The Mössbauer studies show that the complexes remain high spin to 4 K and exclude spin-state changes as the cause of the surprising solid-state thermochromic properties of the complexes. Counterintuitive results of spectroscopic and structural studies showed that methyl substitution at the 3- and 5- positions of the pyrazolyl rings reduces the ligand field strength through steric effects whereas methyl substitution at the 4-position of the pyrazolyl rings increases the ligand field strength through inductive effects.
Disciplines :
Chemistry
Author, co-author :
Morin, Tyler J; Marquette University > Chemistry
Wanniarachchi, Sarath; Marquette University > Chemistry
Gwengo, Chengeto; Marquette University > Chemistry
Makura, Vitales; Marquette University > Chemistry
Tatlock, Heidi M; Marquette University > Chemistry
Lindeman, Sergey V; Marquette University > Chemistry
Bennett, Brian; Medical College of Wisconsin > Biophysics
Long, Gary J; Missouri University of Science and Technology > Chemistry
Grandjean, Fernande ; Université de Liège - ULiège > Département de physique > Département de physique
Gardinier, James R
Language :
English
Title :
Pyrazolyl methyls prescribe the electronic properties of iron(II) tetra(pyrazolyl)lutidine chloride complexes
Alternative titles :
[en] Les groupes méthyl-pyrazolyl gouvernent les propriétés électroniques des complexes de fer(II) tetra(pyrazolyl)lutidine chlorure.
R. T. Jonas T. D. P. Stack J. Am. Chem. Soc. 1997 119 8566
C. R. Goldsmith T. D. P. Stack Inorg. Chem. 2006 45 6048
C. R. Goldsmith A. P. Cole T. D. P. Stack J. Am. Chem. Soc. 2005 127 9904
M. E. De Vries R. M. LaCrois G. Roelfes H. Koijman A. L. Spek R. Hage B. L. Feringa Chem. Commun. 1997 1549
G. Roelfes V. Vrajmasu K. Chen R. Y. N. Ho J.-U. Rohde C. Zondervan R. M. La Crois E. P. Lutz M. Schudde A. L. Spek R. Hage B. L. Feringa E. Munck L. Que Jr. Inorg. Chem. 2003 42 2639
E. L.-W. Wong G.-S. Fang C-M. Che N. Zhu Chem. Commun. 2005 4578
T. J. Morin B. Bennett S. V. Lindeman J. R. Gardinier Inorg. Chem. 2008 47 7468
T. J. Morin A. Merkel S. V. Lindeman J. R. Gardinier Inorg. Chem. 2010 49 7992
K. I. The' L. K. Peterson Can. J. Chem. 1973 51 422
K. I. The' L. K Peterson E. Kiehlman Can. J. Chem. 1973 51 2448
L. K. Peterson E. Kiehlman A. R. Sanger K. I. The' Can. J. Chem. 1974 52 2367
U. Luening R. Baumstark K. Peters H. G. Von Schnering Liebigs Ann. Chem. 1990 1990 2 129
M. W. A. Steenland W. Lippens G. G. Herman A. M. Goeminne Bull. Soc. Chim. Belg. 1993 102 239
G. J. Long F. Grandjean D. L. Reger Spin crossover in pyrazolylborate and pyrazolylmethane complexes Topics in Current Chemistry 2004 233
(Spin Crossover in Transition Metal Compounds I, P. Gütlich, H. A. Goodwin, ed., Springer, Heidelberg), 91-122
O. Graziani P. Hamon J.-Y. Thepot L. Toupet P. A. Szilagyi G. Molnar A. Bousseksou M. Tilset J.-R. Hamon Inorg. Chem. 2006 45 5661
J. M. Smith J. R. Long Inorg. Chem. 2010 49 11223
B. A. Leita S. M. Neville G. J. Halder B. Moubaraki C. J. Kepert J.-F. Létard K. S. Murray Inorg. Chem. 2007 46 8784
J. M. Holland J. A. McAllister C. A. Kilner M. Thornton-Pett A. J. Bridgeman M. A. Halcrow J. Chem. Soc., Dalton Trans. 2002 548
A. L. Thompson A. E. Goeta J. A. Real A. Galet M. C. Muñoz Chem. Commun. 2004 1390
P. Manikandan K. Padmakumar K. R. J. Thomas B. Varghese H. Onodera P. T. Manoharan Inorg. Chem. 2001 40 6930
B. F. Little G. J. Long Inorg. Chem. 1978 17 3401
W. M. Reiff, G. J. Long, in Mössbauer Spectroscopy Applied to Inorganic Chemistry, G. J., Long, Ed., Volume 1, Plenum Press, New York, 1984, p. 245-285
G. K. Shenoy, F. E. Wagner, G. M. Kalvius, in Mössbauer Isomer Shifts, G. K. Shenoy, F. E. Wagner, ed., North-Holland, Amsterdam, 1978, p. 49
R. Ingalls Phys. Rev. 1964 A133 787
D. L. Reger J. D. Elgin M. D. Smith F. Grandjean L. Rebbouh G. J. Long Polyhedron 2006 25 2616
D. L. Reger J. R. Gardinier J. D. Elgin M. D. Smith D. Hautot G. J. Long F. Grandjean Inorg. Chem. 2006 45 8862
D. L. Reger J. R. Gardinier S. Bakbak W. Gemmill M. D. Smith L. Rebbouh F. Grandjean A. M. Shahin G. J. Long J. Am. Chem. Soc. 2005 127 2303
D. L. Reger J. R. Gardinier M. D. Smith A. M. Shahin G. J. Long L. Rebbouh F. Grandjean Inorg. Chem. 2005 44 1852
D. F. Evans J. Chem. Soc. 1959 2003
D. F. Evans G. V. Fazakerley R. F. Phillips J. Chem. Soc. A 1971 1931
I. Noviandri K. N. Brown D. S. Fleming P. T. Gulyas P. A. Lay A. F. Masters L. Phillips J. Phys. Chem. B 1999 103 6713
X. Chen J. She Z.-C. Shang J. Wu P. Zhang Synth. Commun. 2009 39 947
D. Chambers W. A. Denny J. S. Buckleton G. R. Clark J. Org. Chem. 1985 50 4736
SMART APEX2 Version 2.1-4, SAINT+ Version 7.23a and SADABS Version 2004/1. Bruker Analytical Xray Systems, Inc., Madison, Wisconsin, USA, 2005
Oxford Diffraction (2009). CrysAlisPro. Version 1.171.33.55 Oxford Diffraction Ltd, Yarnton, Oxfordshire, England
G. M. Sheldrick, SHELXTL Version 6.12; Bruker Analytical X-ray Systems, Inc., Madison Wisconsin, USA, 2001