Structures of the solvated organic-based ferromagnet decamethylferrocenium tetracyanoethenide, [FeCp*2](*+)[TCNE]*- x yRCN (R = Me, Et, n-Pr).
The ferromagnet [FeCp*(2)][TCNE] (T(c) = 4.80 K) has two structural phase transitions at 249 and 282 K that has thwarted the determination of its structure by single crystal X-ray diffraction; however, its structure at 100 K is reported [P2(1)/c, a = 9.710(1) A, b = 14.214(2) A, c = 18.753(2) A, beta = 113.207(2) degrees, V = 2378.7(5) A(3), Z = 4, T = 100 K]. Because of the facile loss of solvent, the ferromagnetic solvates, [FeCp*(2)][TCNE] x yS {S = MeCN [y = 1, P, a = 9.556(2) A, b = 9.781(2) A, c = 16.152(2) A, alpha = 74.860(2) degrees, beta = 84.333(3) degrees, gamma = 65.030(4) degrees, V = 1321.0(4) A3, Z = 2, T = 100 K], EtCN [y = 1/2, Pnma, a = 14.750(5) A, b = 10.577(5) A, c = 33.972(10) A, V = 5301(3) A3, Z = 8, T = 100 K], n-PrCN [y = 1/2, C2/m, a = 35.902(6) A, b = 10.488(2) A, c = 14.302(2) A, beta = 101.396(3) degrees, V = 5279(1) A(3), Z = 8, T = 173 K]} have also been difficult to crystallographically characterize, but have been determined from single crystal X-ray diffraction data. These structures consist of parallel chains of alternating [FeCp*(2)](*+) and [TCNE](*-) ions, with an intrachain Fe...Fe distance of 10.54 +/- 0.09 A. The solvates additionally possess chains of solvent that separate the alternating chains of [FeCp*(2)](*+) and [TCNE](*-) ions. The MeCN solvate forms layers of chains that separate two rows of chains, while the EtCN and n-PrCN solvates form chains surrounded by six chains, and have fewer nonmagnetic coupling pathways that result in higher ordering temperature with respect to the MeCN solvate.
Miller
Joel S
JS
Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, USA.
Gantzel
Peter K
PK
Rheingold
Arnold L
AL
Taliaferro
Michelle L
ML