Structure and Dynamics in a Bis(perfluoroalkyl)triazapentadiene Methylmercury Compound

Abstract

The compound [Ph2N3C2(C3F7)2]HgCH3 was synthesized from Na[Ph2N3C2(C3F7)2] and CH3HgCl. In solution, it exists as a mixture of two isomers that interconvert slowly on the NMR time scale. Both isomers feature a η1-Ph2N3C2(C3F7)2 ligand. In the asymmetrical one, the CH3Hg group is bonded to one of the two terminal nitrogen atoms. In the more stable symmetrical isomer, [PhNC(C3F7)]2NHgCH3, mercury is attached to the central nitrogen atom. It is this isomer that crystallizes and that was characterized by X-ray diffraction. Thermodynamic parameters for the CH3Hg shift reaction were obtained by DNMR spectroscopy. 19F NMR spectra were analyzed. A metallotropic rearrangement was not observed in [Ph2N3C2(C3F7)2]AuPPh3.

Monomeric Thallium(I) Complexes of Fluorinated Triazapentadienyl Ligands

“…[1][2][3] We have recently investigated the chemistry of triazapentadienyl ligands [9,10] as these ligands show an interesting ability to vary their mode of coordination to fit the needs of the metal fragment. [9][10][11][12] Thallium(i) derivatives of triazapentadienyl ligands are of particular interest because they could serve as good ligand-transfer agents (like the commonly used thallium adducts of poly(pyrazolyl)borates and diazapentadienyl systems). [1,3,[13][14][15][16] [10] these protons give rise to nine separate doublets and four separate septets.…”

“…[10,12,17] To clarify whether Tl···arene contacts are "enforced" by the W-shape ligand conformation that places the aryl groups in a quasi-perpendicular arrangement (see Figure 1) or energetically driven, we undertook a computational study. A density functional (B3LYP/CEP-31G(d)) geometry optimization of D 6 [Tl(h 6 -benzene) 2 ] + yields a Tl-Ct distance of 2.92 , [15] Hybrid quantum/molecular mechanical calculations (see Figure 2 and the Supporting Information) on a full experimental model (geometries optimized starting from the three different molecules in the asymmetric unit of 1 b) yield commensurate Tl-p-arene interaction energies of 13 kcal mol À1 .…”

“…[9][10][11][12] The two lowest energy conformations found for the full ligand models at the PM3 level of theory are U-shaped and Wshaped, [17] with the U-shaped conformer being only 0.1 kcal mol À1 lower in energy than the W-shaped conformer. Hence, these conformations are essentially degenerate.…”

Monomeric Thallium(I) Complexes of Fluorinated Triazapentadienyl Ligands

“…For example, the CN distance and CNC and NCN angles of the W‐shaped ligand backbone are very similar in 1 a and 1 b , in the related anion [N{C(C 3 F 7 )NPh} 2 ] − ,24 and in the κ 1 N (central)‐bonded metal adducts [LM{N[C(C 3 F 7 )N(dipp)] 2 }] (LM=MeCNAg, t BuNCAg, MeHg) 10. 12, 17…”

“…We have recently investigated the chemistry of triazapentadienyl ligands9, 10 as these ligands show an interesting ability to vary their mode of coordination to fit the needs of the metal fragment 9–12. Thallium( I ) derivatives of triazapentadienyl ligands are of particular interest because they could serve as good ligand‐transfer agents (like the commonly used thallium adducts of poly(pyrazolyl)borates and diazapentadienyl systems) 1.…”