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

The molecular and electronic structures, stabilities, bonding features, and magnetoresponsive properties of three‐membered [ c ‐Ln 3 ] +/0/− (Ln = La, Ce, Pr, Nd, Gd, Lu) and heterocyclic six‐membered [ c ‐Ln 3 E 3 ] q (Ln = La, Ce, Pr, Nd, Gd, Lu; E = C, N; q = 0 or 1) rings have been investigated by means of electronic structure calculation methods at the DFT level. The [ c ‐Ln 3 ] +/0/− clusters are predicted to be bound with respect to dissociation to their constituent atoms, the estimated binding energies ranging from 45.8 to 2056.4 kJ/mol. The [ c ‐Ln 3 ] rings capture easily a planar three‐coordinated nitrogen atom at the center or above the center of the ring yielding the lanthanide nitride clusters [ c ‐Ln 3 (μ 3 ‐N)] adopting a planar geometry, except [ c ‐La 3 (μ 3 ‐N)] which exhibits pyramidal geometry. The [ c ‐Ln 3 (μ 3 ‐N)] clusters are predicted to be bound, with respect to dissociation to N ( 4 S) atom and [ c ‐Ln 3 ] clusters in their ground states, the binding energies ranging from 53.9 to 257.9 kcal/mol. The six‐membered [ c ‐Ln 3 E 3 ] q rings are predicted to be bound with respect to dissociation to LnE q monomers in their ground states with dissociation energies in the range of 173.8 to 318.0 kcal/mol. Calculation of the NICS zz ‐scan curves of the clusters predicted a “hermaphrodic” magnetic response of the [ c ‐Ln 3 ] +/0/− and heterocyclic six‐membered [ c ‐Ln 3 E 3 ] q rings, manifested by the coexistence of successive diatropic (aromatic) and paratropic (antiaromatic) zones. The [ c ‐La 3 ] +/0/− and [ c ‐Lu 3 ] − are predicted to be weakly antiaromatic, the [ c ‐Lu 3 ] 0/+ , [ c ‐Lu 3 C 3 ] + , and [ c ‐Lu 3 N 3 ] double (σ+π) aromatic, and the [ c ‐Gd 3 C 3 ] and [ c ‐Gd 3 N 3 ] + rings (σ+δ)‐aromatic systems. © 2010 Wiley Periodicals, Inc. J Comput Chem, 2011