Cooperative Bond Activation Reactions with Ruthenium Carbene Complex PhSO₂(Ph₂PNSiMe₃)CRu(<i>p</i>‑cymene): RuC and N–Si Bond Reactivity

The synthesis of ruthenium carbene complex PhSO₂(Ph₂PNSiMe₃)­CRu­(<i>p</i>-cymene) (<b>3</b>) and its application in cooperative bond activation reactions were studied. Compound <b>3</b> is accessible via salt metathesis using the dilithium methandiide ligand or alternatively via dehydrohalogenation of the corresponding chlorido complex <b>2</b>. The carbene complex was studied by X-ray crystallography, multielement NMR spectroscopy, and DFT studies, all of which confirm the presence of a RuC double bond. The polarization of the RuC bond is less pronounced than in an analogous carbene complex with a thiophosphoryl instead of the iminophosphoryl moiety. This should be beneficial for realizing reversible activation processes by the addition of element-hydrogen bonds across the RuC double bond. Accordingly, <b>3</b> is more stable and the RuC linkage less reactive in the activation of aromatic alcohols and elemental dihydrogen, showing reversible processes and longer reaction times. Despite the selective addition of dihydrogen across the Ru–C bond, the activation of O–H bonds was accompanied by hydrolysis of the N–Si linkage. The reaction of <b>3</b> with water led to the hydrolysis of the N–Si bond as well as protonative cleavage of the central P–C bond in the ligand backbone, thus resulting in the formation of an unusual dinuclear ruthenium–imido complex

Cooperative Bond Activation Reactions with Ruthenium Carbene Complex PhSO₂(Ph₂PNSiMe₃)CRu(<i>p</i>‑cymene): RuC and N–Si Bond Reactivity

The synthesis of ruthenium carbene complex PhSO₂(Ph₂PNSiMe₃)­CRu­(<i>p</i>-cymene) (<b>3</b>) and its application in cooperative bond activation reactions were studied. Compound <b>3</b> is accessible via salt metathesis using the dilithium methandiide ligand or alternatively via dehydrohalogenation of the corresponding chlorido complex <b>2</b>. The carbene complex was studied by X-ray crystallography, multielement NMR spectroscopy, and DFT studies, all of which confirm the presence of a RuC double bond. The polarization of the RuC bond is less pronounced than in an analogous carbene complex with a thiophosphoryl instead of the iminophosphoryl moiety. This should be beneficial for realizing reversible activation processes by the addition of element-hydrogen bonds across the RuC double bond. Accordingly, <b>3</b> is more stable and the RuC linkage less reactive in the activation of aromatic alcohols and elemental dihydrogen, showing reversible processes and longer reaction times. Despite the selective addition of dihydrogen across the Ru–C bond, the activation of O–H bonds was accompanied by hydrolysis of the N–Si linkage. The reaction of <b>3</b> with water led to the hydrolysis of the N–Si bond as well as protonative cleavage of the central P–C bond in the ligand backbone, thus resulting in the formation of an unusual dinuclear ruthenium–imido complex

Cooperative Bond Activation Reactions with Ruthenium Carbene Complex PhSO₂(Ph₂PNSiMe₃)CRu(<i>p</i>‑cymene): RuC and N–Si Bond Reactivity

The synthesis of ruthenium carbene complex PhSO₂(Ph₂PNSiMe₃)­CRu­(<i>p</i>-cymene) (<b>3</b>) and its application in cooperative bond activation reactions were studied. Compound <b>3</b> is accessible via salt metathesis using the dilithium methandiide ligand or alternatively via dehydrohalogenation of the corresponding chlorido complex <b>2</b>. The carbene complex was studied by X-ray crystallography, multielement NMR spectroscopy, and DFT studies, all of which confirm the presence of a RuC double bond. The polarization of the RuC bond is less pronounced than in an analogous carbene complex with a thiophosphoryl instead of the iminophosphoryl moiety. This should be beneficial for realizing reversible activation processes by the addition of element-hydrogen bonds across the RuC double bond. Accordingly, <b>3</b> is more stable and the RuC linkage less reactive in the activation of aromatic alcohols and elemental dihydrogen, showing reversible processes and longer reaction times. Despite the selective addition of dihydrogen across the Ru–C bond, the activation of O–H bonds was accompanied by hydrolysis of the N–Si linkage. The reaction of <b>3</b> with water led to the hydrolysis of the N–Si bond as well as protonative cleavage of the central P–C bond in the ligand backbone, thus resulting in the formation of an unusual dinuclear ruthenium–imido complex

Coupled Oscillators for Tuning Fluorescence Properties of Squaraine Dyes

Combining a squaraine (S) and a BODIPY (B) chromophore in a heterodimer (SB) and two heterotrimers (BSB and SBS) by alkyne bridges leads to the formation of coupled oscillators whose fluorescence properties are superior compared to the parent squaraine chromophore. The lowest energy absorption and emission properties of these superchromophores are mainly governed by the squaraine part and are shifted by more than 1000 cm^–1 to the red by excitonic interaction between the squaraine and the BODIPY dye. Employing polarization-dependent transient absorption and fluorescence upconversion measurements, we could prove that the lowest energy absorption in SB and BSB is caused by a single excitonic state but by two for SBS. Despite the spectral red-shift of their lowest absorption band, the fluorescence quantum yields increase for SB and BSB compared to the parent squaraine chromophore SQA. This is caused by intensity borrowing from the BODIPY states, which increases the squared transition moments of the lowest energy band dramatically by 29% for SB and 63% for BSB compared to SQA. Thereby, exciton coupling leads to a substantial enhancement of fluorescence quantum yield by 26% for SB and by 46% for BSB and shifts the emission from the red into the near-infrared. In this way, the BODIPY-squaraine conjugates combine the best properties of each class of dye. Thus, exciton coupling in heterodimers and -trimers is a valuable alternative to tuning fluorescence properties by, e.g., attaching substituents to chromophores