Structure and spectroscopic properties of the dimeric copper(I) N-heterocyclic carbene complex [Cu₂(CNC(t-Bu))₂](PF₆)₂.

In recent years, the use of copper N-heterocyclic carbene (NHC) complexes has expanded to fields besides catalysis, namely medicinal chemistry and luminescence applications. In the latter case, multinuclear copper NHC compounds have attracted interest, however, the number of these complexes in the literature is still quite limited. Bis[μ-1,3-bis(3-tert-butylimidazolin-2-yliden-1-yl)pyridine]-1κ(4)C(2),N:N,C(2');2κ(4)C(2),N:N,C(2')-dicopper(I) bis(hexafluoridophosphate), [Cu2(C19H25N5)2](PF6)2, is a dimeric copper(I) complex bridged by two CNC, i.

Direct Synthesis and Bonding Properties of the First μ(2)-η(2),η(2)-Allyl-Bridged Diiridium Complex.

The direct synthesis of the first μ(2)-η(2),η(2)-allyl-bridged diiridium complex ([2](+)), bearing the uncommon counterion [IrCl2(COD)](-) ([3](-)), is described. Both bridging moieties in [2](+), namely, allyl and acetate, are introduced in a single reaction step from [{IrCl(COD)}2] (1) and allyl acetate. A combination of X-ray crystallography and density functional theory calculations reveals pronounced metal-allyl π-back-bonding.

Rational synthesis and characterization of dimolybdenum(II) compounds bearing ferrocenyl-containing ligands toward modulation of electronic coupling.

Three novel cis-to-trans-converted dimolybdenum(II) complexes, trans-[Mo2(O2C-Fc)2(DPPX)2][BF4]2 {2a-2c; DPPX = DPPA [N,N-bis(diphenylphosphino)amine], DPPM [1,1-bis(diphenylphosphino)methane], and DPPE [1,2-bis(diphenylphosphino)ethane], respectively}, were synthesized through the insertion of bulky diphosphine ligands, which force a permanent trans arrangement, as evidenced by X-ray crystallography and density functional theory calculations. All compounds were characterized by means of NMR, UV-vis, and IR spectroscopy as well as thermogravimetry-mass spectrometry measurements. Interestingly, uncommon UV-vis transitions and oxidation sequences were observed compared to previously reported ones.

On the concept of hemilability: insights into a donor-functionalized iridium(I) NHC motif and its impact on reactivity.

Novel iridium(I) complexes bearing N-donor-functionalized N-heterocyclic carbene ligands were synthesized. Although hemilabile coordination of the attached donor is considered beneficial in catalysis, no detailed study of this phenomenon in these systems is available to date. The present report provides insight into the hemilabile bonding properties of a N,N'-bis(pyridin-2-yl)-imidazolylidene (NCN) ligand motif on iridium(I).