Diagnosis of magnetoresponsive aromatic and antiaromatic zones in three‐membered rings of d‐ and f‐block elements

Abstract

Magnetoresponsive three-membered rings of d- and f-block elements have been thoroughly investigated with the help of electronic structure calculation methods. The magnetic response of the clusters was evaluated by the Nucleus Independent Chemical Shifts (NICS)(zz)-scan curves, which in conjunction with symmetry-based selection rules for the most significant translationally and rotationally allowed transitions helped rationalize and predict the orbital-type of aromaticity/antiaromaticity of the clusters. The magnetoresponsive early (Groups 3, 4, and 5) transition metal M(3) rings exhibit successive aromatic and antiaromatic zones separated by a nodal plane. The magnetoresponsive late (Groups 11 and 12) transition metal M(3) rings exhibit long-range aromatic zone with the NICS(zz)(R) values decaying rapidly and monotonically with respect to R. The magnetic response of Group 10 transition metal M(3) rings is similar to that of the early transition metal M(3) rings, but it is long-range antiaromatic only for the [c-Ni(3)] cluster. The NICS(zz)-scan curve of the [(H(t)La)(3)(mu(2)-H)(6)] cluster is indicative of weak pure sigma-aromaticity due to the induced diatropic ring current from the translationally allowed a(1)(') --> e' and e' --> a(1)(') transitions. The aromatic-antiaromatic behavior of the [(H(t)Ce)(3)(mu(2)-H)(6)](+) and [(H(t)Tm)(3)(mu(2)-H)(6)](2-) clusters is similar to that of the early d-block elements. The magnetic response of [(H(t)Yb)(3)(mu(2)-H)(6)](3-) is similar to that of [c-Hg(3)](2-). The [(H(t)Lu)(3)(mu(2)-H)(6)] cluster can be considered as a doubly (sigma + pi) aromatic system, with the sigma-aromatic component being much stronger than the pi-aromatic one. Finally, the [(X(t)Re)(3)(mu(2)-X)(6)] and [(X(t)Ru)(3)(mu(2)-X)(6)](+) (X = Cl, Br, I) clusters exhibit significant aromatic character with the greatest contribution to the induced diatropic ring currents coming from pi-type transitions.

A Critical Assessment of the Performance of Magnetic and Electronic Indices of Aromaticity

“…In addition, Tsipis has recently analyzed NICS zz profiles in several organic and inorganic compounds cages [115] as well as in lanthanide three-membered rings [116].…”

Diagnosis of the σ-, π- and (σ+π)-Aromaticity by the Shape of the NICSzz-Scan Curves and Symmetry-Based Selection Rules

“…Finally, the recently developed Anisotropy of the Current Induced Density (ACID) mapping was suggested as a better probe of aromaticity [42,43]. Recently, we showed that the NICS zz -scan curves in conjunction with symmetry-based selection rules for the lowest translationally-and rotationally-allowed transitions help rationalize and predict the orbital-type of aromaticity/antiaromaticity in magnetoresponsive three-membered rings of d-and fblock elements [44], and unequivocally probe the antiaromaticity in a wide range of antiaromatic organic and inorganic rings/cages [45]. Therefore, we thought it would be advisable to test the efficiency of the NICS zz -scan profiles in conjunction with symmetry-based selection rules to provide a clear picture of the orbital type (s-, p-, d-, f-orbital) of aromaticity in a wide range of aromatic organic and inorganic molecules, proving its general use as a powerful diagnostic tool of the orbital type of aromaticity/antiaromaticity.…”

Structural, electronic, and magnetoresponsive properties of triangular lanthanide clusters and their free‐standing nitrides

“…34,[56][57][58][59] Heine et al 92,93 showed that the NICS zz component is directly connected to z-component of the induced magnetic field, which is the vector field originally proposed by Pople to understand aromaticity. 94 The NICS zz -scan profiles of the [c-Ln 3 ] (Ln 5 La, Ce, Pr, Nd, Gd, Lu) clusters are shown in Figure 2, while the most salient features of the NICS zz -scan curves along with the magnetic anisotropy, Dv m are compiled in Figure 4, while the most salient features of the NICS zz -scan curves are compiled in Figure 6, while the most salient features of the NICS zz -scan curves are compiled in intensively investigated.…”

“…In this work, the magnetic response of the clusters was evaluated by the NICS zz -scan curves, which in conjunction with symmetry-based selection rules for the most significant translationally (T x,y ) and rotationally (R z ) allowed transitions help rationalize and predict the orbital-type of aromaticity/antiaromaticity of the clusters. 34,[56][57][58][59] Magnetic susceptibilities were computed by the Continuous Set of Gauge Transformations method, [87][88][89] as implemented in the GAUSSIAN03 series of programs 67 using the B3LYP/STRSC level of theory. Table 2.…”

“…The aromatic-antiaromatic behavior of the [(H t Ce) 3 3 (l 2 -H) 6 ] 22 clusters is similar to that of the early d-block elements. 34 Very recently, 35 we thoroughly investigated by means of electronic structure calculation methods (DFT), the molecular and electronic structures, stabilities, bonding features, and magnetic properties of prototypical planar isocyclic c-U n X n (n 5 3, 4; X 5 O, NH) and heterocyclic c-U n (l 2 -X) n (n 5 3, 4; X 5 C, CH, NH) clusters as well as the E@[c-U 4 (l 2 -C) 4 ], (E 5 H 1 , C, Si, Ge) and U@[c-U 5 (l 2 -C) 5 ] molecules including a planar tetracoordinate element E (ptE) and pentacoordinate U (ppU) at the ring centers, respectively. It was shown that 5f orbitals significantly contribute to the cyclic electron delocalization and the associated magnetotropicity of the clusters.…”