Abstract
Manganese tetraphenylporphyrin bromide and iodide Mn(TPP)X (X = Br, 2; I, 3; TPP2− = meso-tetraphenylporphyrinate) are synthetic analogs of Mn(III) geoporphyrins. Crystal structures of 2 and 3 with chloroform in the lattices, Mn(TPP)Br·CHCl3 (2·CHCl3), Mn(TPP)I·CHCl3 (3·CHCl3), Mn(TPP)I·CDCl3 (3·CDCl3 in a different space group from 3·CHCl3), Mn(TPP)I·1.5CHCl3 (3·1.5CHCl3), and 2 with dichloromethane in the lattice, Mn(TPP)Br·CH2Cl2 (2·CH2Cl2), have been determined by single-crystal X-ray diffraction at 100 K or 298 K. Hirshfeld surface analyses of the crystal structures of 2·CHCl3, 2·CH2Cl2, 3·CHCl3, 3·CDCl3 and 3·1.5CHCl3 have been performed. Surprisingly the Mn(III)–Br and Mn(III)–I bonds in Mn(TPP)X (2–3) are about 0.2 Å (8%) longer than Fe(III)–Br and Fe(III)–I bonds in S = 5/2 Fe(TPP)X (X = Br, 4; I, 5), although both Mn(III) and Fe(III) ions have the same radii. Magnetic properties of 2 and 3 have been studied by direct current (DC) and alternating current (AC) susceptibility measurements, high-field electron paramagnetic resonance (HFEPR), and inelastic neutron scattering (INS). With four unpaired electrons in Mn(TPP)X (X = Br, 2; I, 3), the bromide complex 2 in 2·CDCl3 possesses easy-axis anisotropy, as does the chloride analog Mn(TPP)Cl (1), with the axial (D) and rhombic (E) zero-field splitting parameters of D = –1.091(3) cm−1 and |E| = 0.087(2) cm−1. The iodide complex 3 in 3·CDCl3 becomes easy-plane with D = +1.30(1) cm−1 and |E| = 0.010(5) cm−1. Axial ZFS parameters D change from −2.290(5) cm−1 in 1, reported earlier, to −1.091(3) cm−1 in 2 and +1.30(1) cm−1 in 3.
Original language | English |
---|---|
Article number | 114488 |
Journal | Polyhedron |
Volume | 184 |
DOIs | |
State | Published - Jul 1 2020 |
Funding
The authors thank financial support by the U.S. National Science Foundation ( CHE-1633870 and CHE-1900296 to Z-L.X.; NSF-DMR-1350002 to H.D.Z.) and a Shull Wollan Center Graduate Research Fellowship (S.E.S. and Z.L.). Acknowledgment is also made to the Donors of the American Chemical Society Petroleum Research Fund for partial support of this work. Part of this work was done at the National High Magnetic Field Laboratory, which is supported by U.S. National Science Foundation through Cooperative Agreement DMR-1644779 and the State of Florida. Part of the research used resources at the Spallation Neutron Source, a Department of Energy (DOE) Office of Science User Facility operated by ORNL. The magnetic measurements were conducted in part at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. We thank Dr. A. Ozarowski for the EPR simulation and fitting software SPIN. The authors thank financial support by the U.S. National Science Foundation (CHE-1633870 and CHE-1900296 to Z-L.X.; NSF-DMR-1350002 to H.D.Z.) and a Shull Wollan Center Graduate Research Fellowship (S.E.S. and Z.L.). Acknowledgment is also made to the Donors of the American Chemical Society Petroleum Research Fund for partial support of this work. Part of this work was done at the National High Magnetic Field Laboratory, which is supported by U.S. National Science Foundation through Cooperative Agreement DMR-1644779 and the State of Florida. Part of the research used resources at the Spallation Neutron Source, a Department of Energy (DOE) Office of Science User Facility operated by ORNL. The magnetic measurements were conducted in part at the Center for Nanophase Materials Sciences, which is a DOE Office of Science User Facility. We thank Dr. A. Ozarowski for the EPR simulation and fitting software SPIN.
Keywords
- HFEPR
- Hirshfeld surface analysis
- Mn porphyrin complexes
- inelastic neutron scattering (INS)
- zero-field splitting (ZFS)