A Dinitrogen Dicopper(I) Complex via a Mixed‐Valence Dicopper Hydride

Abstract

Low-temperature reaction of the tris(pyrazolyl)borate copper(II) hydroxide [(iPr2) TpCu]2 (μ-OH)2 with triphenylsilane under a dinitrogen atmosphere gives the bridging dinitrogen complex [(iPr2) TpCu]2 (μ-1,2-N2 ) (3). X-ray crystallography reveals an only slightly activated N2 ligand (N-N: 1.111(6) Å) that bridges between two monovalent (iPr2) TpCu fragments. While DFT studies of mono- and dinuclear copper dinitrogen complexes suggest weak π-backbonding between the d(10) Cu(I) centers and the N2 ligand, they reveal a degree of cooperativity in the dinuclear Cu-N2 -Cu interaction. Addition of MeCN, CNAr(2,6-Me) , or O2 to 3 releases N2 with formation of (iPr2) TpCu(L) (L=NCMe, CNAr(2,6-Me2) ) or [(iPr2) TpCu]2 (μ-η(2) :η(2) -O2 ) (1). Addition of triphenylsilane to [(iPr2) TpCu]2 (μ-OH)2 in pentane allows isolation of a key intermediate [(iPr2) TpCu]2 (μ-H) (5). Although 5 thermally decays under N2 to give 3, it reduces unsaturated substrates, such as CO and HC≡CPh to HC(O)H and H2 C=CHPh, respectively.

A Dicopper Platform that Stabilizes the Formation of Pentanuclear Coinage Metal Hydride Complexes

“…Reactivity studies revealed that the hydride has significant anionic character, undergoing protonolysis with mild acids like MeOH, and insertion with electrophiles like CO 2 and 3‐hexyne. More recently, Warren has demonstrated that reduction of a dicopper(II) hydroxide complex with Ph 3 SiH results in the ultimate formation of a bridging dicopper(I) dinitrogen complex . Strikingly, the authors were able to show that this reaction proceeded through a transient mixed‐valent copper(I)/copper(II) monohydride intermediate (Scheme , middle), which they were able to characterize by EPR spectroscopy and X‐ray diffraction studies.…”

Uncovering Redox Non-Innocent H-Bonding in Cu(I)-Diazene Complexes

“…We note that the related dicopper dinitrogen complex [ iPr2 TpCu] 2 (-N 2 ) has been structurally and spectroscopically characterized with an N-N distance of 1.111(6) Å and (NN) = 2130 cm -1 pointing to a gently reduced N 2 ligand. 73 We modeled these redox tautomers 9a' -9d' by DFT as triplet species because in the prototypical case of 9c' (Figure 14b), the triplet configuration is 7 kcal/mol more stable than the unrestricted open-shell singlet 9c'-singlet (Table S3). Although these pyridinium radical/dinitrogen redox tautomers [ xHetH TpCu] 2 ( -N 2 ) (9a' -9d') are calculated to be 6.4 -20.2 kcal/mol higher in free energy at 298 K than the corresponding H-bonded diazene complexes [ xHet TpCu] 2 ( -N 2 H 2 ) (2a' -2d'), there is a clear trend in their relative stabilities (Figure 14c).…”

Designing and controlling the morphology of spherical molecularly imprinted polymers

“…A dual-template (molecular imprinting template and mesoporous template) docking oriented molecular imprinting method for one-pot synthesis of mesoporous MIPs with recognition sites located on the surface of mesoporous silica was proposed. [202][203][204][205][206] As shown in Fig. 8C, rod-like positively charged CTAB micelles were mixed with negatively charged template to form dualtemplate complexes based on electrostatic attraction.…”

“…9E shows a TEM image of phosphate-imprinted mesoporous silica using the dual-template method, with mesopore diameter of 2.6 nm and specific surface area of 792 m 2 g À1 . 204 Similarly, Hu 205 prepared mesoporous MIPs to recognize phosphorylated tyrosine residue using this dual-template docking method. Template phenylphosphonic acid is negatively charged in alkaline solution, which can be docked onto CTAB micelles to form a dual-template due to electrostatic attraction.…”