A High-Spin Organometallic Fe−S Compound: Structural and Mssbauer Spectroscopic Studies of [Phenyltris((tert-butylthio)methyl)borate]Fe(Me)

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• 作者：Codrina V. Popescu ; Michael T. Mock ; Sebastian A. Stoian ; William G. Dougherty ; Glenn P. A. Yap ; Charles G. Riordan
• 刊名：Inorganic Chemistry
• 出版年：2009
• 出版时间：September 7, 2009
• 年：2009
• 卷：48
• 期：17
• 页码：8317-8324
• 全文大小：831K
• 年卷期：v.48,no.17(September 7, 2009)
• ISSN：1520-510X

文摘

The synthesis and structure of the pseudotetrahedral, sulfur-rich, high-spin organoiron(II) [phenyltris((tert-butylthio)methyl)borate]Fe(Me), [PhTt^tBu]Fe(Me), 1, are reported. Low-temperature Mssbauer spectroscopic studies reveal an isomer shift of δ = 0.60(3) mm/s and ΔE_Q = 0.00(1) mm/s and an S = 2 ground multiplet with a negative zero-field splitting, D = −33(3) cm⁻¹, E/D ≈ 0.01. The small separation of the ground doublet, Δ ≈ 0.01 cm⁻¹, allows for observation of X-band EPR signals at g_eff ≈ 10 (g_z = 2.6, g_x,y = 2.00). The relatively large negative zero-field splitting and a highly anisotropic magnetic hyperfine tensor, containing a large orbital z component, {−10(4), −10(4), +33.8(2) MHz}, are concordant with the presence of unquenched orbital angular momentum. Density functional theory (DFT) calculations predict that the lowest-lying orbitals have predominantly d_xy- and d_x²−y²-like character, separated by an energy gap small enough to allow mixing through spin−orbit coupling, to generate a negative zero-field splitting, consistent with the experimental observations. The experimental and DFT-calculated isomer shifts are in good agreement (δ(calcd) = 0.5 mm/s). The unusual (for a high-spin ferrous site) null electric field gradients can be qualitatively explained in the frame of the spin−orbit coupling mixing. The very small Fermi contact component of the magnetic hyperfine tensor (A_FC(exp) = −9 MHz) is not well described by the DFT approach (A_FC(calcd) = +2 MHz). To our knowledge, this is the first study of a sulfur-coordinated high-spin organoiron(II) complex.