| 11428118 |
Blakesley DW, Payne SC, Hagen KS: Spin-state variation in solid state and solution of mononuclear iron (II) 1,4,7-trimethyl-1,4,7-triazacyclonane complexes. Inorg Chem. 2000 May 1;39(9):1979-89.
The series of mononuclear iron (II) complexes with the tridentate macrocycle Me3tacn have been prepared (Me3tacn = 1,4,7-trimethyl-1,4,7-triazacyclonane). A purple, spin-crossover complex [Fe (Me3tacn)(MeCN) 3](CF3-SO3) 2 (1-OTf) forms in acetonitrile but readily loses MeCN ligands to form a colorless high-spin complex Fe (Me3tacn)(OTf) 2 (2). The BPh4- salt of 1 is stable to loss of MeCN and remains purple even under a vacuum. Methylene chloride solutions of Fe (OTf) 2 and Me3tacn afford crystals of [Fe (Me3tacn)(MeCN) 2 (OTf)](OTf) (3). Crystallization of 1-OTf in the presence of water affords a colorless high-spin complex, Fe (Me3tacn)(H2O)(CF3-SO3) 2 (4), that exists as a pair of molecules bridged by hydrogen bonds between the coordinated water and the two bound triflate anions of the inversion-related partner. The crystallographic parameters are the following. 1-BPh4: C63H70B2Fe, monoclinic, P2 (1)/c, a = 18.360 (1) A, b = 11.761 (1) A, c = 25.754 (2) A, beta = 90.72 (1) degrees, Z = 4. 3: C16H29Cl2F6FeN5O6S2, triclinic group P1, a = 8.500 (1) A, b = 11.421 (2) A, c = 15.677 (2) A, alpha = 92.23 (1) degrees, beta = 94.79 (1) degrees, gamma = 97.03 (1) degrees, Z = 2. 4: C20H18F6FeN4O6S2, monoclinic, P2 (1)/n, a = 11.253 (3) A, b = 12.624 (5) A, c = 14.683 (5) A, beta = 94.02 (2) degrees, Z = 4. Variable temperature visible spectra and 1H NMR spectra of solutions of both 1-OTf and 1-BPh4 exhibit low-spin, high-spin crossover behavior, whereas 2, 3, and 4 remain high-spin in solution. The extensive role of coordinated triflate as a terminal and/or bridging ligand as well as a counteranion is demonstrated by variable temperature 19F NMR spectra. |
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