Dual luminescence and infrared circularly polarized luminescence up to 900 nm with platinum complexes bearing a helical donor-acceptor ligand.

Chiral molecular materials able to emit circularly polarized luminescence (CPL) have attracted considerable interest in the last few decades, due to the potential of CP-light in a wide range of applications. While CP luminescent molecules with blue, green, and yellow emissions are now well-reported, NIR CPL from organic and organometallic compounds lags behind due to the dual challenge of promoting radiative deexcitation of the excited state in this low energy region while assuring a significant magnetic dipole transition moment, a prerequisite for generating CPL. Based on a versatile axially chiral arylisoquinoline ligand, we report the synthesis and chiroptical properties of chiral donor-acceptor platinum(ii) complexes displaying CPL that extends up to almost 900 nm.

Cleavage of Carbon Dioxide C=O Bond Promoted by Nickel-Boron Cooperativity in a PBP-Ni Complex.

The synthesis and characterization of ( PBP)Ni(OAc) (5) by insertion of carbon dioxide into the Ni-C bond of ( PBP)NiMe (1) is presented. An unexpected CO cleavage process involving the formation of new B-O and Ni-CO bonds leads to the generation of a butterfly-structured tetra-nickel cluster ( PBOP) Ni (μ-CO) (6). Mechanistic investigation of this reaction indicates a reductive scission of CO by O-atom transfer to the boron atom via a cooperative nickel-boron mechanism.

Ethylene Dimerization and Oligomerization Using Bis(phosphino)boryl Supported Ni Complexes.

We report the dimerization and oligomerization of ethylene using bis(phosphino)boryl supported Ni(II) complexes as catalyst precursors. By using alkylaluminum(III) compounds or other Lewis acid additives, Ni(II) complexes of the type (PBP)NiBr (R = Bu or Ph) show activity for the production of butenes and higher olefins. Optimized turnover frequencies of 640 mol·mol·s for the formation of butenes with 41(1)% selectivity for 1-butene using (PBP)NiBr, and 68 mol·mol·s for butenes production with 87.

σ-GeH and Germyl Cationic Pt(II) Complexes.

The low electron count Pt(II) complexes [Pt(NHC')(NHC)][BAr] (where NHC is a -heterocyclic carbene ligand and NHC' its metalated form) react with tertiary hydrogermanes HGeR at room temperature to generate the 14-electron platinum(II) germyl derivatives [Pt(GeR)(NHC)][BAr]. Low-temperature NMR studies allowed us to detect and characterize spectroscopically some of the σ-GeH intermediates [Pt(η-HGeR)(NHC')(NHC)][BAr] that evolve into the platinum-germyl species. One of these compounds has been characterized by X-ray diffraction studies, and the interaction of the H-Ge bond with the platinum center has been analyzed in detail by computational methods, which suggest that the main contribution is the donation of the H-Ge to a σ*(Pt-C) orbital, but backdonation from the platinum to the σ*(Ge-H) orbital is significant.

Reversible carbon-boron bond formation at platinum centers through σ-BH complexes.

A reversible carbon-boron bond formation has been observed in the reaction of the coordinatively unsaturated, cyclometalated, Pt(ii) complex [Pt(I BuPr')(I BuPr)][BAr], , with tricoordinated boranes HBR. X-ray diffraction studies provided structural snapshots of the sequence of reactions involved in the process. At low temperature, we observed the initial formation of the unprecedented σ-BH complexes [Pt(HBR)(I BuPr')(I BuPr)][BAr], one of which has been isolated.