Dynamic behavior in solution of seven-coordinated transition metal complexes

Syntheses, solid structures, and behavior in solution of [MI2(CO)3(pyrazole)2] complexes (M = Mo, W)

“…First, the most stable complex is that found in the crystal structure in all the cases, except for 6, where both isomers are found in the crystal structure. Second, the values found are really small, as previously reported for other sudies on differences of energy between the possible geometries in heptacoordinated complexes [6]. Therefore, trying to establish clear rules about which would be the preferred geometry for a given complex is so far a target out of reach.…”

“…Geometry optimizations were performed under no symmetry restrictions, using initial coordinates derived from X-ray data of the same complexes, and frecuency analyses were performed to ensure that a minimum structure with no imaginary frecuencies was achieved in each case. 218.1097 69.958 410.800 414.9302 7b, Å 12.696 312.2469 312.626 514.841 618.2043 5c, Å 12.377 39.0308 312.324 512.411 515.0096 6α, deg 90 90 90 90 90 β, deg 96.536 (6) 93.927 396.372 791.552 7101.492 (4 Jose M. Martín-Alvarez, a Daniel Miguel, a and Fernando Villafañe* ,a a GIR Facultad de Ciencias,Campus Miguel Delibes,Universidad de Valladolid,47011 Valladolid,Spain. b Anorganische Chemie,Technische Universität Dortmund,44227 Dortmund, Germany.…”

“…The dynamic behavior in solution of heptacoordinated complexes has been recently reviewed by one of us [6], and one of the general conclusions reached therein is that the dynamic processes are so diverse that finding a regular pattern is a very difficult task. For heptacoordinated complexes with a capped octaedron geometry, the exchange processes so far reported include both scrambling and migration of ligands.…”

“…On the other hand, the nature of these processes do not seem to depend on the type of ligands present. In addition, their energies are usually rather similar and the dynamic processes often occur simultaneously [6].…”

“…Research on heptacoordinated complexes is somehow limited due to the limitations associated to the characterization of the complexes, what is a consequence of the small differences of energy between the possible geometries. Besides, most of the heptacoordinated complexes reported show a dynamic behavior in solution, what makes even more difficult their complete characterization [6].…”