A cyclopentadienyl functionalized silylene-a flexible ligand for Si- And C-coordination

The synthesis of a 1,2,3,4-tetramethylcyclopentadienyl (Cp$^{4}$) substituted four-membered N-heterocyclic silylene [{PhC(NtBu) $_{2}$}Si(C$_{5}$Me$_{4}$H)] is reported first. Then, selected reactions with transition metal and a calcium precursor are shown. The proton of the Cp$_{4}$-unit is labile. This results in two different reaction pathways: (1) deprotonation and (2) rearrangement reactions. Deprotonation was achieved by the reaction of [{PhC(NtBu) $_{2}$}Si(C$_{5}$Me$_{4}$H)] with suitable zinc precursors. Rearrangement to [{PhC(NtBu) $_{2}$}(C$_{5}$Me$_{4}$)SiH], featuring a formally tetravalent silicon R$_{2}$CSi(R′)-H unit, was observed when the proton of the Cp$^{4}$ ring was shifted from the Cp$^{4}$-ring to the silylene in the presence of a Lewis acid. This allows for the coordination of the Cp$^{4}$-ring to a calcium compound. Furthermore, upon reaction with transition metal dimers [MCl(cod)] $_{2}$ (M = Rh, Ir; cod = 1,5-cyclooctadiene) the proton stays at the Cp$^{4}$-ring and the silylene reacts as a sigma donor, which breaks the dimeric structure of the precursors

Molecular gold strings: aurophilicity, luminescence and structure–property correlations

This review covers the compound class of one-dimensional gold strings. These compounds feature a formally infinite repetition of gold complexes as monomers/repeating units that are held together by aurophilic interactions, i.e. direct gold–gold contacts. Their molecular structures are primarily determined in the solid state using single crystal X-ray diffraction. The chemical composition of the employed gold complexes is diverse and furthermore plays a key role in terms of structure characteristics and the resulting properties. One of the most common features of gold strings is their photoluminescence upon UV excitation. The emission energy is often dependent on the distance of adjacent gold ions and the electronic structure of the whole string. In terms of gold strings, these parameters can be fine-tuned by external stimuli such as solvent, pH value, pressure or mechanical stress. This leads to direct structure–property correlations, not only with regard to the photophysical properties, but also electric conductivity for potential application in nanoelectronics. Concerning these correlations, gold strings, consisting of self-assembled individual complexes as building blocks, are the ideal compound class to look at, as perturbations by an inhomogeneity in the ligand sphere (such as the end of a molecule) can be neglected. Therefore, the aim of this review is to shed light on the past achievements and current developments in this area

Triple-decker complexes incorporating three distinct deck architectures

The reactivity of the dilithioplumbole ([Li$_{2}$(thf)$_{2}$(μ,η$^{5}$-L$^{Pb}$)], L$^{Pb}$ = 1,4-bis-tert-butyl-dimethylsilyl-2,3-bis-phenyl-plumbolyl) towards the reactive pnictogen precursors P$_{4}$, pentaphosphaferrocene, and pentaarsaferrocene ([Cp*Fe(η$^{5}$-E$_{5}$)] (Cp* = η$^{5}$-C$_{5}$Me$_{5}$, E = P, As)) is reported. The reaction with P$_{4}$ afforded a phospholyl lithium complex, via lead-phosphorus exchange, while the reactions with [Cp*Fe(η$^{5}$-E$_{5}$)] yielded the first examples of Pb–Fe–Li heterotrimetallic triple-decker polypnictogenides with three different deck motifs

Heteroleptic copper(I) complexes with coumarin-substituted aminodiphosphine and diimine ligands: synthesis and photophysical studies

The synthesis of heteroleptic Cu(I) complexes with coumarin-functionalized aminodiphosphine and diimine ligands is described. The complexes show yellow to deep-red phosphorescence in the solid state at ambient temperature with quantum yields up to 21%. The emission color of the complexes can be tuned by systematic modifications in the ligand system

3d-4f heterometallic complexes by the reduction of transition metal carbonyls with bulky LnII^{II} amidinates

The redox chemistry between divalent lanthanide complexes bearing bulky amidinate ligands has been studied with 3d transition metal carbonyl complexes (iron and cobalt). The reaction of [(DippForm)$_{2}$Sm$^{ǁ}$(thf)$_{2}$] (DippForm = N,N′-bis(2,6-diisopropylphenyl)formamidinate) with [Co$_{2}$(CO)$_{8}$] resulted in the formation of a tetranuclear Sm–Co complex, [{(DippForm)$_{2}$Sm$^{ǁǀ}$(thf)}$_{2}${(μ-CO)$_{2}$Co(CO)$_{2}$}$_{2}$]. The product of the reaction of [(DippForm)$_{2}$Yb$^{ǁ}$(thf)$_{2}$] and [Co$_{2}$(CO)$_{8}$] gives the dinuclear Yb–Co complex [{(DippForm)$_{2}$Yb$^{ǁǀ}$(thf)}{(μ-CO)Co(CO)$_{3}$}] in toluene. The reaction of [(DippForm)$_{2}$Sm$^{ǁ}$(thf)$_{2}$] was also carried with the neighbouring group 8 carbonyl complexes [Fe$_{2}$(CO)$_{9}$] and [Fe$_{3}$(CO)$_{12}$], resulting in a pentanuclear Sm$^{ǁǀ}$–Fe complex, [{(DippForm)$_{2}$Sm$^{ǁǀ}$}$_{2}${(μ$_{3}$-CO)$_{2}$Fe$_{2}$(CO)$_{9}$}], featuring a triangular iron carbonyl cluster core

Phase‐Dependent Long Persistent Phosphorescence in Coumarin‐Phosphine‐Based Coinage Metal Complexes

A coumarin functionalized aminodiphosphine has been introduced as a bidentate ligand in coinage metal chemistry. Mono-, di-, and trimetallic copper and silver complexes were synthesized with this ligand. The hybrid character of the ligand led to compounds with rich luminescence properties. These include coumarin-based blue fluorescence, observed as a sole emission in solution at room temperature, and green phosphorescence, which is efficient at low temperatures and dominates the spectra of the metal complexes. In the rigid environment of frozen solutions, the green phosphorescence shows an unusually long (for metal complexes) decay on the seconds timescale in high quantum yield. In addition, a red phosphorescence, which may be assigned to the triplet state localized in the phosphine-M$_{3}$Cl$_{2}$ (M=Cu, Ag), is observed for the trinuclear complexes at low temperature. Neither the second-long phosphorescence nor the red emission is observed for the coumarin ligand, thus they must be a result of the coordination to coinage metal clusters. The excited states in these compounds were also investigated by femtosecond transient absorption spectroscopy and quantum chemical calculations