Tricarbonylrhenium(I) and -technetium(I) complexes with bis(2-pyridyl)phenylphosphine and tris(2-pyridyl)phosphine

Calix[4]arene-Analogous Technetium Supramolecules

Calix[4]arene-analogous technetium supramolecules (1 and 2) were assembled using (NBu₄)[Tc₂(μ-Cl)₃(CO)₆] and neutral flexible bidentate nitrogen-donor ligands (L¹ and L²) consisting of four arene units covalently joined via methylene units. The neutral homoleptic technetium macrocycles adopt a partial cone/cone-shaped conformation in the solid state. These supramolecules are the first example of fac-[Tc(CO)₃]⁺ core-based metallocalix[4]arenes and second example of fac-[Tc(CO)₃]⁺ core-based metallomacrocycles. Structurally similar fac-[Re(CO)₃]⁺ core-based macrocycles (3 and 4) were also prepared using [Re(CO)₅X] (where X = Cl or Br) and L¹ or L². The products were characterized spectroscopically and by X-ray analysis.

Towards rainbow photo/electro-luminescence in copper(i) complexes with the versatile bridged bis-pyridyl ancillary ligand

The synthesis and characterization of a family of copper(i) complexes bearing a bridged bis-pyridyl ancillary ligand is reported, highlighting how the bridge nature impacts the photo- and electro-luminescent behaviours within the family. In particular, the phosphonium bridge led to copper(i) complexes featuring good electrochemical stability and high ionic conductivity, as well as a stark blue-to-orange luminescence shift compared to the others. This resulted in high performance light-emitting electrochemical cells reaching stabilities of 10 mJ at ca. 40 cd m^-2 that are one order of magnitude higher than those of the other complexes. Overall, this work sheds light onto the crucial role of the bridge nature of the bis-pyridyl ancillary ligand on the photophysical features, film forming and, in turn, on the final device performances.

Variable coordination of tris(2-pyridyl)phosphine and its oxide toward M(hfac)2: a metal-specifiable switching between the formation of mono- and bis-scorpionate complexes

An unexpected substitution of the anionic chelating ligands at the M^II centre by a neutral tripodal ligand has been observed in the reaction of Mn^II, Co^II, Ni^II and Cu^II hexafluoroacetylacetonates (hfac) with tris(2-pyridyl)phosphine (Py₃P) or its oxide (Py₃P = O). The nature of the metal ion in M(hfac)₂ and the M/L ratio determine the degree of substitution of hfac-anions (partial vs. total) and therefore, the structure of the complex formed (scorpionate vs. bis-scorpionate ones, respectively). Hence, the reaction of the ligands with [Cu(hfac)₂(H₂O)₂] in an equimolar ratio affords scorpionate [Cu(N,N',N''-Py₃P = X)(O,O'-hfac)(O-hfac)], wherein one hfac-ligand chelates metal, while the other hfac acts as an O-monodentate one. Using the two equivalents of Py₃P in this reaction leads to [Cu(N,N',N''-Py₃P)₂](hfac)₂, which contains a bis-scorpionate cation [Cu(Py₃P)₂]²⁺ and two noncoordinated hfac-anions. [Co(hfac)₂(H₂O)₂] and [Ni(hfac)₂(H₂O)₂], regardless of the M/L molar ratio, react with Py₃P = O to give cationic scorpionates [M(N,N',N''-Py₃P = O)(O,O'-hfac)(H₂O)](hfac), in which one hfac-anion is noncoordinated. In contrast, [Mn(hfac)₂(H₂O)₂], on interaction with Py₃P, results in the cationic complex [Mn(N,N',N''-Py₃P)₂][Mn(hfac)₃]₂ bearing a bis-scorpionate cation [Mn(Py₃P)₂]²⁺ and two [Mn(hfac)₃]₂^- counterions. The synthesized scorpionates have been characterized by X-ray diffractometry, cyclic voltammetry, SQUID magnetometry, FT-IR and UV-Vis techniques.