Synthesis and Characterization of Cationic [Tris(pyrazolyl)methane]copper(I) Carbonyl and Acetonitrile Complexes

Abstract

The reaction of [Cu(NCMe)4]PF6 with equimolar amounts of the tris(substituted-pyrazolyl)methane ligands HC(3,5-Me2pz)3, HC(3-Phpz)3, and HC(3-Butpz)3 yields the respective salts {[HC(3,5-Me2pz)3]Cu(NCMe)}PF6, {[HC(3-Phpz)3]Cu(NCMe)}PF6, and {[HC(3-Butpz)3]Cu(NCMe)}PF6. These complexes are unusually resistant toward reaction with dioxygen. These acetonitrile complexes react with carbon monoxide to yield the stable complexes {[HC(3,5-Me2pz)3]Cu(CO)}PF6, {[HC(3-Phpz)3]Cu(CO)}PF6, and {[HC(3-Butpz)3]Cu(CO)}PF6, respectively. The solid-state structures of {[HC(3-Butpz)3)]Cu(NCMe)}PF6·CH2Cl2 and {[HC(3-Butpz)3]Cu(CO)}PF6 have been determined by X-ray crystallography. The structures are very similar, with the Cu−N distances to the donor atoms of the HC(3-Butpz)3 ligand 0.03 Å shorter in the carbonyl complex.

Dinuclear copper(I) complexes of tris(3,5-dimethylpyrazol-1-yl)methane: Synthesis, structure, and reactivity

“…The Cu-N distances for the tridentate ligand vary from 2.053(2) to 2.1377(19) Å (average 2.087 Å ). The fourth Cu-N distance to the nitrogen atom of acetonitrile is much shorter at 1.871(2) Å , which is similar to previously reported complex [Cu(HC(3-Bu t Pz) 3 )(NCMe)](PF 6 )[10]. This may imply that the steric hindrance at the third position of the pyrazolyl rings does not significantly affect the bonding distance and strength of the acetonitrile complexes because this ligand is not very space demanding.…”

“…The model structures of some copper(I)-containing proteins were obtained by X-ray crystallography or NMR spectroscopy [6][7][8][9]. In those structures, tris(pyrazolyl)methane, hydrotris(pyrazolyl)borate and other N3 ligand donor sets coordinate to the copper(I) centers are employed because of their facially coordinating ability [6,[8][9][10][11]. Our interest is in developing copper(I) complexes containing nitrogen donor tripodal ligand sets [12], which are very important in bioinorganic chemistry area.…”

Reactivity of bulky tris(phenylpyrazolyl)methanesulfonate copper(I) complexes towards small unsaturated molecules

“…Exclusively by using a relatively high CO pressure (20 atm) in a closed vessel containing acetonitrile solution of 1, was possible to isolate from a methanol solution the expected carbonyl complex [Cu(Tpms Ph )(CO)] (4) after ca. 12 h. The observed difficulty in the preparation of 4, in contrast [70], bearing the neutral tris(phenylpyrazolyl)methane, and similar compounds of tris(pyrazolyl)borate and tris(pyrazolyl) methane [71], and suggesting [72] the retention of the N 2 O-coordination mode of the scorpionate in 4.…”

Tris(pyrazolyl)phosphine Oxide and Tris(triazolyl)phosphine Oxide Scorpion Ligands

“…We next tried to introduce a CO ligand by exposing a solution of the presumed tris(triazolyl)phosphine oxide Cu I complex in CH 2 Cl 2 to a CO atmosphere in an analogous freeze-pump-thaw procedure that was used for the HCand OP-based pyrazolyl ligands B [31] and C. [9] Whereas at ambient temperature the reaction mixture was a suspension under N 2 , thawing under CO gave a clear solution from which a precipitate resulted upon addition of pentane. This material did not show a CO frequency by IR spectroscopy in contrast to products obtained from the same procedure used for ligands B and C. We presume that the CO ligation to the [E Ph Cu][PF 6 ] complex is relatively weak and that the labile carbonyl species formed loses its ligand once the CO pressure is released.…”