Manipulating the Substituent Sphere of a Bicyclic Silicon(I) Ring Compound Results in Anionic Cubane-Type Clusters and a Tetrahedral Silanide.

The reaction of the bicyclic silicon(I) ring compound Si{N(SiMe)Mes} 1 with strong zwitterionic character and moderate sterical demand of the amido substituents with two equivalents of KC was investigated. This resulted in the unexpected abstraction of two amido substituents from 1 and additionally in dimerization to a dianionic Si cluster compound 2 with four unsubstituted silicon atoms and two [K([18]crown-6)] counter cations. Performing this reaction in the absence of [18]crown-6 results in release of only one amido substituent from 1 and dimerization to a dianionic Si cluster 3 with only two unsubstituted silicon atoms.

Antiprotozoal Pt(II) Complexes as Luminophores Bearing Monodentate P/As/Sb-Based Donors: An X-ray Diffractometric, Photoluminescence, and Sb- Spectroscopic Study with TD-DFT-Guided Interpretation and Predictive Extrapolation toward Bi.

In this study, it is demonstrated that the radiative rate constant of phosphorescent metal complexes can be substantially enhanced using monodentate ancillary ligands containing heavy donor atoms. Thus, the chlorido coligand from a Pt(II) complex bearing a monoanionic tridentate C^N*N luminophore ([]) was replaced by triphenylphosphane (PPh) and its heavier pnictogen congeners (i.e.

Dual Emissive Zn(II) Naphthalocyanines: Synthesis, Structural and Photophysical Characterization with Theory-Supported Insights towards Soluble Coordination Compounds with Visible and Near-Infrared Emission.

Metal phthalocyaninates and their higher homologues are recognized as deep-red luminophores emitting from their lowest excited singlet state. Herein, we report on the design, synthesis, and in-depth characterization of a new class of dual-emissive (visible and NIR) metal naphthalocyaninates. A 4-,-dimethylaminophen-4-yl-substituted naphthalocyaninato zinc(II) complex () and the derived water-soluble coordination compound () exhibit a near-infrared fluorescence from the lowest ligand-centered state, along with a unique push-pull-supported luminescence in the visible region of the electromagnetic spectrum.

Neutral and Cationic Re(I) Complexes with Pnictogen-Based Coligands and Tunable Functionality: From Phosphorescence to Photoinduced CO Release.

In this work, we have explored Re(I) complexes featuring triphenylpnictogen (, = , , or )-based coligands and bidentate (neutral or monoanionic) luminophores derived from 1,10-phenantroline (), as well as from 2-(3-(-butyl)-1-1,2,4-triazol-5-yl)pyridine (). The effect of the increasingly heavy elements on the structural parameters, photoexcited-state properties, and electrochemical behavior as well as the hybridization defects and polarization of the atoms was related to the charges of the main luminophores (i.e.

One Dianionic Luminophore with Three Coordination Modes Binding Four Different Metals: Toward Unexpectedly Phosphorescent Transition Metal Complexes.

This work reports on a battery of coordination compounds featuring a versatile dianionic luminophore adopting three different coordination modes (mono, bi, and tridentate) while chelating Pd(II), Pt(II), Au(III), and Hg(II) centers. An in-depth structural characterization of the ligand precursor (H L) and six transition metal complexes ([HLPdCNtBu], [LPtCl], [LPtCNtBu], [LPtCNPhen], [HLHgCl], and [LAuCl]) is presented. The influence of the cations and coordination modes of the luminophore and co-ligands on the photophysical properties (including photoluminescence quantum yields (Φ ), excited state lifetimes (τ), and average (non-)radiative rate constants) are evaluated at various temperatures in different phases.

Formation of CC and CC κ-Chelate Complexes through Competitive sp- and sp-CH Activations: An Experimental and Computational Study.

Depending on the chelate ring present, cyclometalated complexes are useful catalysts for various reactions. The reactivity of Ir and Rh NHC complexes bearing aliphatic or aromatic N,N'-substituents and thus featuring various metalation sites toward cyclometalation has been investigated. The Rh complex bearing an -mesityl-'-benzyl-NHC does not participate in any cyclometalation, while the Ir complex reacts under metalation of an -methyl group of the Mes substituent to give complex [] with a six-membered chelate ring.

The Effect of Monodentate Co-Ligands on the Properties of Pt(II) Complexes Bearing a Tridentate C^N*N-Luminophore.

In this study, the insertion of different monodentate co-ligands on Pt(II) complexes bearing a monoanionic C^N*N luminophore as a tridentate chelator was achieved beyond the previously reported chlorido- ([]) and cyanido-decorated ([]) analogues. To investigate the impact of the auxiliary ligand on the photophysical properties, we introduced a neutral carbonyl-ligand and observed a lower photoluminescence quantum yield () than with a cyanido moiety. However, the direct substitution of the chlorido co-ligand by a NO-related derivative was not successful.

Pt(II) Complexes with Tetradentate C^N*N^C Luminophores: From Supramolecular Interactions to Temperature-Sensing Materials with Memory and Optical Readouts.

A series of four regioisomeric Pt(II) complexes ( and ) bearing tetradentate luminophores as dianionic ligands were synthesized. Hence, both classes of cyclometallating chelators were decorated with three -hexyl ( = 6) or -dodecyl ( = 12) chains. The new compounds were unambiguously characterized by means of multiple NMR spectroscopies and mass spectrometry.

Silicon Chalcogenide Cage Compounds: New Structures Derived from the Bicyclic Silicon(I) Ring Compound Si {N(SiMe )Mes}.

The bicyclic silicon(I) ring compound Si {N(SiMe )Mes} (2) was used as starting material in reactions with chalcogens and chalcogen transfer agents at low temperatures. This resulted in the selective formation of new cage compounds. With Me NO, a silicon oxide with adamantane-type cage 3 was isolated that represents the first isolated T silsesquioxane.

Unravelling the Roles of Solvophobic Effects and π⋅⋅⋅π Stacking Interactions in the Formation of [2]Catenanes Featuring Di-(N-Heterocyclic Carbene) Building Blocks.

A series of [2]catenanes has been prepared from di-NHC building blocks by utilizing solvophobic effects and/or π⋅⋅⋅π stacking interactions. The dinickel naphthobiscarbene complex syn-[1] and the kinked biphenyl-bridged bipyridyl ligand L yield the [2]catenane [2-IL](OTf) by self-assembly. Solvophobic effects are pivotal for the formation of the interlocked species.

Synthesis and functionalization of the six-vertex anionic amido-substituted silicon cluster [Si{N(SiMe)Ph}].

The reaction of the six-vertex amido-substituted silicon cluster Si{N(SiMe)Ph} 1 with two equiv. of KC results in the abstraction of K{N(SiMe)Ph} and leads to the contact ion pair 2 including an anionic silicon cluster with two unsubstituted pyramidal vertices. Facile functionalization of 2 was achieved with MeI, SiCl and SiBr and results in neutral two-fold functionalized silicon clusters.

Room-Temperature Phosphorescence from Pd(II) and Pt(II) Complexes as Supramolecular Luminophores: The Role of Self-Assembly, Metal-Metal Interactions, Spin-Orbit Coupling, and Ligand-Field Splitting.

The synthesis as well as the structural and photophysical characterization of two isoleptic bis-cyclometalated Pt(II) and Pd(II) complexes, namely [] and [], bearing a tailored dianionic tetradentate ligand () are reported. The isostructural character and intermolecular interactions of [] and [] were assessed by NMR spectroscopy and X-ray diffraction analysis. Both complexes show fully ligand-controlled aggregation, demonstrating that a judicious molecular design can tune the photophysical properties.

Rhenium(I) Complexes with Neutral Monodentate Coligands and Monoanionic 2-(1,2,4-Triazol-5-yl)pyridine-Based Chelators as Bidentate Luminophores with Tunable Color and Photosensitized Generation of O: An Integrated Case Study Involving Photophysics and Theory.

In this work, we describe the synthesis as well as structural, photophysical, and theoretical investigation of a new coordination chemical concept involving rhenium(I) complexes bearing monoanionic 1,2,4-triazolylpyridine-based bidentate chromophores. The X-ray diffractometric analysis of single crystals revealed particular packing features: the trifluoromethylated exemplar displayed two kinds of arrangements of the coordination centers, where the bidentate ligands at the edges of the unit cell are staggered parallel to each other, whereas those inside show antiparallel stacking with respect to the external ligands. On the other hand, the complexes bearing an adamantyl substituent yield a linear arrangement, where the bulky moiety of one luminophore points to the pyridine center of the adjacent ligand of the neighboring complex while including methanol molecules hydrogen-bonded to the triazolato unit.

Comparison of Phosphorescent Pt(II) Complexes with C^N^N vs N^N^N Chelators and Caffeine-Based NHC-co-ligands.

In this work, we explored coordination compounds featuring caffeine-based carbene co-ligands and tridentate dianionic pincer luminophores derived from 2,6-bis(1H-1,2,4-triazol-5-yl)pyridine (N), as well as from 2-phenyl-6-(1H-1,2,4-triazol-5-yl)pyridine (C), bearing either Ad (adamantyl) or tBu (tertiary butyl) substituents. The new 2-phenyl-6-(1H-1,2,4-triazol-5-yl)pyridine-based ligand precursors along with four Pt(II) complexes, namely Pt(C-tBu), Pt(C-Ad), Pt(N-tBu) and Pt(N-Ad) were characterized. Further on, the influence of the different substituents at the chelating luminophores and of the caffeine-based NHC-co-ligand on the photophysical properties (including photoluminescence quantum yields (Φ ), excited-state lifetimes (τ), radiative (k ), and non-radiative (k ) deactivation rate constants) was assessed in fluid solutions at room temperature (RT) and in frozen glassy matrices at 77 K.

Unsaturated amido-substituted six-vertex mixed silicon germanium clusters.

The synthesis of mixed silicon and germanium clusters SiGe{N(SiMe)Dipp}1-3 ( = 3.7, 3.1, 2.

Monoanionic C^N^N Luminophores and Monodentate C-Donor Co-Ligands for Phosphorescent Pt(II) Complexes: A Case Study Involving Their Photophysics and Cytotoxicity.

A family of Pt(II) complexes bearing monoanionic C^N^N ligands as luminophoric units as well as a set of monodentate ligands derived from allenylidene and carbene species were synthesized and characterized in terms of structure and photophysical properties. In addition, we present the extraordinary molecular structure of a phosphorescent complex carrying an allenylidene ligand. Depending on the co-ligand, an effect can be observed in the photoluminescence lifetimes and quantum yields as well as in the radiative and radiation less deactivation rate constants.

An Anionic Amido-Substituted Seven-Vertex Siliconoid Cluster.

The silanide [Si {N(SiMe )Dipp} ] (1) transforms into the anionic siliconoid cluster [Si {N(SiMe )Dipp} ] (2) with four unsubstituted silicon atoms as a contact ion pair with [K([18]crown-6)] in C D at room temperature within five weeks. Anion 2 was investigated by natural population analysis and visualization of intrinsic atomic orbitals. Magnetically induced current-density calculations of 2 revealed two distinct strong diatropic vortices that sum up in one direction and create a strongly shielded apical silicon atom in 2.

Tetracyclic silaheterocycle formed through a pericyclic reaction cascade including a two-fold intramolecular C-C bond activation.

Reductive debromination of the tribromoamidosilane 2 gave the tetracyclic silaheterocycle 3 through a unique reaction cascade involving unprecedented two-fold intramolecular cycloaddition by transient silylenes. Experimental and computational analyses of the reaction mechanism allowed the identification of the key intermediates that lead to the silaheterocycle 3 or, alternatively, to the cyclotrisilene 19.

A strongly twisted SiSi bond with resemblance to a buckled dimer in an unexpected isomer of hexasilabenzene.

The reductive debromination of {N(SiMe)Ph}SiBr1 with Rieke magnesium yields the six-vertex amido-substituted silicon cluster 2 with zwitterionic character that represents an unprecedented isomer of hexasilabenzene. The topology of Si1 and Si2 in 2 has bonding features of a highly twisted disilene and resembles that of a buckled dimer of Si(100)2 × 1 reconstructed surfaces. Cluster 2 forms the adducts 3 and 4 with NHC and DMAP, respectively.

Synthesis and Reactivity of a Neutral Homocyclic Silylene.

Isolation of the neutral homocyclic silylene 2 is possible via amine ligand abstraction with potassium graphite (KC ) and subsequent reaction with SiMe Cl from a bicyclic silicon(I) amide J. This reaction proceeds via an anionic homoaromatic silicon ring compound 1 as an intermediate. The twofold-coordinated silicon atom in the homocyclic silylene 2 is stabilized by an allyl-type π-electron delocalization.

Reactivity of the Bicyclic Amido-Substituted Silicon(I) Ring Compound Si {N(SiMe )Mes} with FLP-Type Character.

The bicyclic amido-substituted silicon(I) ring compound Si {N(SiMe )Mes} 2 (Mes=Mesityl=2,4,6-Me C H ) features enhanced zwitterionic character and different reactivity from the analogous compound Si {N(SiMe )Dipp} 1 (Dipp=2,6- Pr C H ) due to the smaller mesityl substituents. In a reaction with the N-heterocyclic carbene NHC (1,3,4,5-tetramethyl-imidazol-2-ylidene), we observe adduct formation to give Si {N(SiMe )Mes}  ⋅ NHC (3). This adduct reacts further with the Lewis acid BH to yield the Lewis acid-base complex Si {N(SiMe )Mes}  ⋅ NHC  ⋅ BH (4).

Cycloadditions with a Stable Charge-Separated Cyclobutadiene-Type Amido-Substituted Silicon Ring Compound.

Reductive debromination of {N(SiMe ) }SiBr with Rieke magnesium results in the formation of the five-vertex silicon cluster with one bromine substituent Si {N(SiMe ) } Br, 1, and the cyclobutadiene analogue 2 in a 1:1 ratio. The latter features a planar four-membered silicon ring with a charge-separated electronic situation. Two silicon atoms in 2 are trigonal planar and the other two trigonal pyramidal.

Sterically constrained tricyclic phosphine: redox behaviour, reductive and oxidative cleavage of P-C bonds, generation of a dilithium phosphaindole as a promising synthon in phosphine chemistry.

The redox behaviour of sterically constrained tricyclic phosphine was investigated by spectroelectrochemistry. The data suggested a highly negative reduction potential with the reversible formation of a dianionic species. Accordingly, reacted with two equivalents of Li/naphthalene by reductive cleavage of a P-C bond of one of the PC heterocycles.