Spin-Crossover Anticooperativity Induced by Weak Intermolecular Interactions

Abstract

As a rule, rational design of cooperative spin-crossover (SCO) molecular switches is largely based on consideration of sizes and structures of individual building blocks, whereas a meticulous analysis of crystal packing, including the weakest intermolecular interactions, is often assumed to play a secondary role or is even fully neglected. By investigating cobalt(II) clathrochelates, which do not change the molecular volume upon SCO, we showed that even weak (1.2 kcal/mol) π···Cl intermolecular interactions can cause a pronounced anticooperativity of SCO, being more gradual in the solid state than in solution. Our results clearly demonstrate that the "chemical pressure" concept is not as general as it is thought to be, and the successful design of molecular switches requires in-depth analysis of intermolecular interactions, however weak they seem.

The Peculiarities of Ionization, Fragmentation and Association (Macrobicyclization) of Pseudoclathrochelate Zinc, Cobalt, Iron and Manganese(II) tris-Pyrazoloximates in the LDI Mass Spectra

“…«топологи-ческих лекарств» [3][4][5][6] и перспективных парамагнитных проб для использования в структурной биологии. [7,8] В связи с этим представляет несомненный интерес изуче-ние устойчивости и путей фрагментации этих клеточных комплексов как в растворах, так и в газовой фазе. Ранее [9] методом ББА масс-спектрометрии были изучены пути фрагментации гидроксиборсодержащих клатрохелатов железа(II) -производных алициклических диоксимов (Схема 1).…”

Predicting critical temperatures of iron(II) spin crossover materials: Density functional theory plus U approach

“…7,16,17 Second, the spin transition behavior is not only governed by the extensively studied intramolecular ligand fields, 18 but also tailored by the intermolecular interactions in bulk materials. [19][20][21][22][23][24] Therefore, it is necessary to perform calculations for the molecular solids using periodic boundary conditions. 9,25,26 However, the large number of atoms in the unit cell requires much computational effort, and thus makes sophisticated wavefunctionbased methods (e.g., CASPT2 27 ) and hybrid functionals [28][29][30][31] inappropriate.…”

Molecular design of cage iron(ii) and cobalt(ii,iii) complexes with a second fluorine-enriched superhydrophobic shell

“…For example, (3) 1.947 (4) 1.914 (5) 2.125 (3) 1.905 (4) M-N2 (Å) 1.932 (3) 1.891 (4) 1.911 (5) 1.894 (3) 1.926 (4) M-N3 (Å) 1.917 (3) 1.896 (4) 1.924 (5) 1.923 (3) 1.918 (5) M-N4 (Å) 1.940 (3) 1.916 (5) M-N5 (Å) 1.900 (3) 1.914 (4) M-N6 (Å) 1.921 (3) 1.914 (4) M-O2 (Å) 2.042 (4) M-O4 (Å) 2.075 (4) M-O6 (Å) 2.094 (4) N-O (Å) 1.359(4)-1.371 (4) 1.371(5)-1.390 (5) 1.354(6)-1.372 (6) 1.357(4)-1.376 (3) 1.303 (5) (3) 1.497(7)-1.504 (6) 1.476(8)-1.503 (8) 1.490(4)-1.509 (4) 1.502 (7) (3) 1.292(6)-1.324 (6) 1.304(8)-1.314 (8) 1.288(5)-1.308 (4) 1.273 (6) (3) 1.460(6)-1.462 (9) 1.441 (8)-1.457(12) 1.463(5)-1.492 (7) 1.445 (7) 11 while the obtained cage complexes Fe-((CF 3 C 6 F 4 S) 2 Gm) 3 (BC 6 F 5 ) 2 , Co((C 6 F 5 S) 2 Gm) 3 (BC 6 F 5 ) 2 and their earlier-described analog Co((CF 3 C 6 F 4 S) 2 Gm) 3 (Bn-C 4 H 9 ) 2 4b form a pseudoisostructural series (assuming that their apical pentafluorophenyl, n-butyl or 3,5-bis(trifluoromethyl)phenyl groups, and the ribbed CF 3 C 6 H 4 S and C 6 F 5 S substituents are virtually equivalent). For example, (3) 1.947 (4) 1.914 (5) 2.125 …”

“…The filtrate was evaporated to dryness, the solid residue was washed with hexane (6 ml, in two portions) and dried in vacuo. 11 Fe((CF 3 C 6 F 4 S) 2 Gm) 3 (BC 6 F 5 ) 2 . Calc.…”