Komplexchemie P‐reicher Phosphane und Silylphosphane. XXII. Die Bildung von [η2‐{tBu–P=P–SiMe3}Pt(PR3)2]aus (Me3Si)tBuP–P=P(Me)tBu2 und [η2‐{C2H4}Pt(PR3)2]

Coordination Chemistry of P‐rich Phosphanes and Silylphosphanes. XXII. The Formation of [η²‐{^tBu–P=P–SiMe₃}Pt(PR₃)₂] from (Me₃Si)^tBuP–P=P(Me)^tBu₂ and [η²‐{C₂H₄}Pt(PR₃)₂] (Me₃Si)^tBuP–P = P(Me)^tBu₂ reacts with [η²‐{C₂H₄}Pt(PR₃)₂] yielding [η²‐{^tBu–P=P–SiMe₃}Pt(PR₃)₂]. However, there is no indication for an isomer which would be the analogue to the well known [η²‐{^tBu₂P–P}Pt(PPh₃)₂]. The syntheses and NMR data of [η²‐{^tBu–P=P–SiMe₃}Pt(PPh₃)₂] and [η²‐{^tBu–P=P–SiMe₃}Pt(PMe₃)₂] as well as the results of the single crystal structure determination of [η²‐{^tBu–P=P–SiMe₃}Pt(PPh₃)₂] are reported.     

Chiral [1]Rotaxanes: X‐Ray Structures and Chiroptical Properties

New chiral [1]rotaxanes with aromatic bridges were prepared in yields up to 72% starting from a [2]rotaxane with sulfonamide groups in wheel and axle. The X‐ray structures of the parent [2]rotaxane 1 and of the three [1]rotaxanes 3e , g , h were solved which show networks of H‐bonds between wheel and axle. The separation of the racemic mixtures of four of the [1]rotaxanes, i.e., of 3a , b , d , e , was possible with HPLC on Chiralcel OD. The aromatic chromophores in the bridges lead to a considerable enhancement of the intensities of the molar CD as compared to the analogues with aliphatic bridges. In one case ( 3d ), the Cotton effects are as strong as those usually found in helicenes.     

Determination of sulfoxide bond dissociation enthalpies of dibenzothiophene S‐oxide derivatives with computational methods

Photodeoxygenation of dibenzothiophene S‐oxide (DBTO) has been suggested as a clean way to generate atomic oxygen in solution. Sulfoxide bond dissociation enthalpies (BDEs) are important to the quantum yield and mechanism of this photodeoxygenation. In this study, BDE of substituted DBTO molecules with various functional groups were determined using M062X/aug‐cc‐pV(T + d)Z and MP2/aug‐cc‐pV(T + d)Z levels of theory. The sulfoxide BDE was determined using an isodesmic reaction. The observed effect of substitution was that functional groups with negative σ_para values (electron donating) strengthen the sulfoxide bond and that substituents with positive σ_para values (electron withdrawing) weaken the sulfoxide bond. The Mulliken charge on sulfur for DBTO and the corresponding dibenzothiophene were identified as a suitable indicator of the predicted S–O BDE. Moreover, steric and hydrogen bonding interactions were found to affect sulfoxide BDE for certain functional groups when located at the 1 or 4 positions of the substituted DBTO. Copyright © 2014 John Wiley & Sons, Ltd.     

Elektrophile Addition des Thiomethyl-Kations an η-Cyclopentadienyl(ethoxymethylcarben)-(nitrosyl)(trimethylphosphin)molybdän

Carbonyl(η⁵-cyclopentadienyl)(ethoxymethylcarbene)(nitrosyl)molybdenum reacts with trimethylphosphine with substitution of the carbonyl ligand. Subsequent electrophilic addition of the methylthio cation SCH₃⁺ at the nucleophilic carbene carbon atom affords a new cationic molybdathia-cyclopropane system.