Calorimetric studies on [DMeFc][TCNE] and [DMeFc][TCNQ]

Abstract Typical molecular-based magnets, decamethylferrocenium tetracyanoethenide ([DMeFc][TCNE]) and decamethylferrocenium tetracyanoquinodimethanide ([DMeFc][TCNQ]), have been studied by means of adiabatic calorimetry. The Curie temperature of [DMeFc][TCNE] was determined to be Tc - 4.74 K. The excess entropy derived from the observed heat-capacity anomaly was very close to the expected magnetic entropy, 2 R In 2. Detailed analysis of the heat-capacity anomaly revealed that [DMeFc][TCNE] is a good one-dimensional (ID) Ising magnet. Two structural phase transitions were found for the first time at 248.7 and 281.8 K, and attributed to the orientational order-disorder character of the TCNE anion. For [DMeFc][TCNQ] an antiferromagnetic phase transition was observed at TN = 2.54 K. The magnetic lattice anisotropy of the TCNQ salt is smaller than that of the TCNE salt.

[1]  K. Kaji,et al.  An automated adiabatic calorimeter for the temperature range 13 K to 530 K The heat capacities of benzoic acid from 15 K to 305 K and of synthetic sapphire from 60 K to 505 K , 1992 .

[2]  M. Nakano,et al.  Heat capacity of the ferromagnetic molecular charge-transfer complex, decamethylferrocenium tetracyanoethenide: Ising-like property of the magnetic interaction , 1990 .

[3]  Epstein,et al.  Specific heat of decamethylferrocenium tetracyanoethanide (DMeFc)(TCNE). , 1989, Physical review. B, Condensed matter.

[4]  A. Epstein,et al.  Anisotropic magnetic properties and magnetic ordering in molecular decamethylferrocenium tetracyanoethanide , 1988 .

[5]  M. Nakano,et al.  A very low-temperature calorimeter with a (3He+4He) dilution refrigerator The heat capacity of trans-bis(ethylenediamine)-bis(isothiocyanato)nickel(II)☆ , 1987 .

[6]  M. Ward,et al.  Characterization of the charge-transfer reaction between decamethylferrocene and 7,7,8,8-tetracyano-p-quinodimethane (1:1): the 57Fe Mössbauer spectra and structures of the paramagnetic dimeric and the metamagnetic one-dimensional salts and the molecular and electronic structures of [TCNQ]n (n=0, −1 , 1987 .

[7]  A. Epstein,et al.  Ferromagnetism in molecular decamethylferrocenium tetracyanoethenide (DMeFc TCNE) , 1987 .

[8]  A. Epstein,et al.  Ferromagnetic behavior of [Fe(C5Me5)2]+.bul. [TCNE]-.bul.. Structural and magnetic characterization of decamethylferrocenium tetracyanoethenide, [Fe(C5Me5)2]+.bul. [TCNE]-.bul..cntdot.MeCN and decamethylferrocenium pentacyanopropenide, [Fe(C5Me5)2]+.bul. [C3(CN)5]- , 1987 .

[9]  A. Epstein,et al.  Ferromagnetic properties of one-dimensional decamethylferrocenium tetracyanoethylenide (1 : 1): [Fe(η5-C5Me5)2]˙+[TCNE]˙– , 1986 .

[10]  W. Hatfield,et al.  Single Crystal Magnetic Study on Ferromagnetic Manganese (II) Phthalocyanine. , 1983 .

[11]  J. D. Johnson,et al.  Excitation spectrum and low-temperature thermodynamics of the Ising-Heisenberg linear ferromagnet , 1980 .

[12]  G. A. Candela,et al.  Metamagnetic properties of one-dimensional decamethylferrocenium 7,7,8,8-tetracyano-p-quinodimethanide (1:1):[Fe(.eta.5-C5Me5)2]+.cntdot.(TCNQ)-.cntdot. , 1979 .

[13]  H. Suga,et al.  Heat capacity of a five-coordinated ferromagnet, chloro bis(N,N-diethyldithiocarbamato)iron(III), in the temperature range from 0.4 to 20 K , 1977 .

[14]  Y. Imry,et al.  Generalized Ginzburg-Landau theory of pseudo-one-dimensional systems , 1975 .

[15]  R. Sherwood,et al.  Paramagnetic Anisotropy, Electronic Structure, and Ferromagnetism in Spin S = 32 Manganese(II) Phthalocyanine , 1970 .

[16]  H. Williams,et al.  Spin-3/2 Iron Ferromagnet: Its Mössbauer and Magnetic Properties , 1967 .

[17]  G. S. Rushbrooke,et al.  High-Temperature Series Expansions for the Spin-½ Heisenberg Model by the Method of Irreducible Representations of the Symmetric Group , 1964 .