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.
Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, USA.
Joel S
JS
Miller
Peter K
PK
Gantzel
Arnold L
AL
Rheingold
Michelle L
ML
Taliaferro