Synthesis, properties and structures of methyldiphenylphosphonium 1-indenylide, 1-C9H6PMePh2, and its chiral tricarbonylchromium(0) complex Cr(η5-1-C9H6PMePh2)(CO)3

Phosphonium-substituted Diphosphaindenylide (PPI): Exploration of Biradical Character and Ligand Properties

Starting from C6 H4 (PCl2 )2 and the TMS-substituted ylide (TMS)2 C=PR3 (TMS=trimethylsilyl, R=p-tolyl), the phosphonium-substituted diphosphaindenylide PPI was prepared in two steps. CASSCF calculations as well as the reactivity toward diphenyl acetylene suggest a notable biradical character in PPI. Reaction with [Cr(CO)3 (MeCN)3 ] affords the complex [Cr(CO)3 (η5 -PPI)] (5). This complex was employed to explore the ligand properties of PPI, which demonstrates considerable potential through the combination of strong metal-ligand interactions and the possibility of a pronounced indenyl effect.

Reactions of Dilithium Dibenzopentalenides with Cr(CO)3 (CH3 CN)3 : Unexpected Formation of a Cubic Tetramer of an Anionic Hydrodibenzopentalenyl Complex

To explore the coordination chemistry of dibenzopentalene dianion, reactions of two dilithium dibenzopentalenides having different silyl substituents with Cr(CO)₃ (CH₃ CN)₃ were investigated. The products were unexpected anionic complexes, [Li(Et₂ O)]⁺ [Cr(η⁵ -9-hydrodibenzopentalenyl)(CO)₃ ]^- . The proton at the 9-position is derived from Cr(CO)₃ (CH₃ CN)₃ , as evidenced by the use of Cr(CO)₃ (CD₃ CN)₃ . The X-ray diffraction analysis revealed that the chromium is coordinated by an anionic five-membered ring of the pentalene skeleton, and the lithium atom is coordinated by oxygen atoms of the carbonyl groups. The complexes form a dimer or a cage-like tetramer via carbonyl-lithium interactions, depending on the bulk of the silyl groups. The cubic tetramer appears to retain its cage structure in nonpolar solvents such as benzene.

Synthesis and structure of a new phosphonium-1-indenylide (PHIN) ligand, 4,7-dimethyl-1-C9H4PMePh2, and of new PHIN complexes of rhodium and iridium

New complexes of rhodium(i) and iridium(i) containing the η⁵-PHIN ligands 1-C₉H₆PMePh₂ (I) and 4,7-dimethyl-1-C₉H₄PMePh₂ (II) are described.

Ferrocenyl-phosphonium ionic liquids - synthesis, characterisation and electrochemistry

New unsymmetrically substituted ferrocenyl-phosphonium ionic liquids (ILs) [FcPR2R']NTf2 are synthesized by two or three step syntheses starting from ferrocene, Fc = (C5H5)Fe(C5H4); R = Me, (n)Bu, (n)Hex, Ph; R' = Me, (n)Pr, (n)Bu, Ph; NTf2 = N(SO2CF3)2. The selective synthesis of alkyl phosphines FcPR2via a Friedel-Crafts phosphorylation is highlighted as an alternative for the standard protocol commonly used for ferrocenyl arylphosphines involving lithiation of FcH followed by phosphorylation. The influence of the P-substituents on thermal stability, electrochemical potential, chemical shift, and UV-Vis absorption behavior of the ILs is studied. The phosphonium group acts both as an ionic tag and as an electron-withdrawing substituent directly bound at the Cp-ring position. Therefore the title compounds are attractive for further studies to use them as tunable redox mediators for (photo)electrochemical devices such as dye sensitized solar cells (DSSCs) or redox flow batteries.