Thiopyridazine-Based Copper Boratrane Complexes Demonstrating the Z-type Nature of the Ligand.
In Z-type ligands the electrons for the coordination bond are formally provided by the metal. They represent an important addition to the much more extensively used L- and X-type σ-donor ligands for the development of transition metal complexes with new reactivities. We report here a new boron Z-type ligand with three tethering thiopyridazinyl donors forming exclusively complexes that feature a metal boron bond. Rational substitution pattern in the backbone of the pyridazinyl heterocycle led to a well-behaved ligand system that allowed preparation of a series of copper boratrane complexes in high yields. They are found to be more soluble in common organic solvents allowing reactivity studies in contrast to previous complexes with this type of ligand. Thus, copper complexes [Cu{B(Pn(Me,tBu))3}X] with X = Cl, OTf, N3, and κN-NCS are reported. Solution behavior was explored, and the molecular structures were determined by single-crystal X-ray diffraction analyses. The thiocyanate ligand is found to coordinate via its nitrogen atom pointing to a high oxidation state of the copper. Density functional theory calculations indicate a high positive charge on copper and a strong copper-boron interaction. Thus, here reported complexes deliver synthetic evidence for the Z-type nature of the ligand. These findings are important for further dissemination of these types of ligands in coordination chemistry.
Institute of Chemistry, University of Graz , Schubertstrasse 1, 8010 Graz, Austria.
Stefan
S
Holler
Institute of Chemistry, University of Graz , Schubertstrasse 1, 8010 Graz, Austria.
Michael
M
Tüchler
Institute of Chemistry, University of Graz , Schubertstrasse 1, 8010 Graz, Austria.
Ferdinand
F
Belaj
Centro de Química Estrutural, Instituto Superior Técnico, Universidade de Lisboa , Av. Rovisco Pais No. 1, 1049-001 Lisboa, Portugal.
Luis F
LF
Veiros
Institute of Applied Synthetic Chemistry, Vienna University of Technology , Getreidemarkt 9, 1060 Vienna, Austria.
Karl
K
Kirchner
Institute of Chemistry, University of Graz , Schubertstrasse 1, 8010 Graz, Austria.
Nadia C
NC
Mösch-Zanetti