Magnetic, electronic, and vibrational properties of metal and fluorinated metal phthalocyanines

Abstract

The magnetic and electronic properties of metal phthalocyanines (MPc) and fluorinated metal phthalocyanines (F 16 MPc) are studied by means of spin density functional theory (SDFT). Several metals (M) such as Ca, all first d-row transition metals and Ag are investigated. By considering different open shell transition metals it is possible to tune the electronic properties of MPc, in particular the electronic molecular gap and total magnetic moment. Besides assigning the structural and electronic properties of MPc and F 16 MPc, the vibrational modes analysis of the ScPc-ZnPc series have been studied and correlated to experimental measurements when available.

“Pigments of Life”, Molecules Well Suited to Investigate Metal–Ligand Symmetry‐Restricted Covalency

“…At variance to PcCu, whose 3d 9 Cu II central ion unambiguously implies a 2 B 1g GS, the square‐planar coordination of the 3d 3 V II ion in PcV may generate either a high‐spin (HS) or a low‐spin (LS) configuration with three ( S = 3/2) or one ( S = 1/2) unpaired electrons respectively. BP86 ADF (Supporting Information), results recently published by our group[16f] stated that the PcV HS 4 E g electronic state (see Figure ) is more stable than the LS 2 B 1g one by more than 16 kcal/mol and, even though such a result perfectly agrees with conclusions of Arillo‐Flores et al, it has to be noted that Eguchi et al assigned the PcV V III L 2,3 ‐edge XAS features by assuming on a qualitative ground a LS V electronic configuration corresponding to a 1g 0 b 2g 2 e g 1 b 1g 0 /a 1g 0 b 2g 0 e g 0 b 1g 0 ( 2 E g ).…”

Electronic transport properties of (fluorinated) metal phthalocyanine

“…For the last five columns in the table, Co ... Ag, we note, first of all, that the total MM of the respective isolated molecules are close to 1, 0, 1, 0, 1 μ B , respectively [34]. Thus it is apparent that the coupling to the leads has a significant effect in all cases for MPc, while the disturbance due to the leads is rather small for the fluorinated counterparts (considering first U= 0).…”

“…For the Fe case, the MM of isolated FePc happens to be close to 2 μ B , but is found to be strongly increased in the junction due to the overlap between Au orbitals and molecular orbitals, the MM on Fe being roughly doubled. Apparently this coupling induces a transition from a low-spin to a high-spin state, unlike the case of, e.g., Mn which is already in a high-spin state for isolated MnPc; see [34], tables 1 and 2. Thus Fe is an exceptional example where the coupling to the leads has a pronounced effect on the magnetic properties.…”

“…In order to obtain further insight into the above results, we also study the charge and spin density isosurfaces of the considered systems. For example, the charge isosurface of isolated ScPc was presented already in [34] ( figure 2), with the result that there is hardly any charge on the metal. In the transport situation, this does not change; however, due to the good coupling to the Au leads, which is mediated by the above-mentioned addition of an S atom, some charge is being transferred to the contact region.…”

“…The electronic and magnetic properties of isolated MPc and F 16 MPc molecules have been studied before [34], where it was found that the MM is carried mainly by the metal atom. Below we will compare, in particular, isolated molecules with molecules connected to leads, with emphasis on the differences.…”