Catalyzed M–C coupling reactions in the synthesis of σ-(pyridylethynyl)dicarbonylcyclopentadienyliron complexes

The reactions between terminal ethynylpyridines, (trimethylsilyl)ethynylpyridines and cyclopentadienyliron dicarbonyl iodide were studied under Pd/Cu-catalyzed conditions to develop a synthetic approach to the σ-alkynyl iron complexes Cp(CO)₂Fe–C Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> C–R (R = ortho-, meta-, para-pyridyl). Depending on the catalyst and reagents used, the yields of the desired σ-pyridylethynyl complexes varied from 40 to 95%. In some cases the reactions with ortho-ethynylpyridine gave as byproduct the unexpected binuclear FePd μ-pyridylvinylidene complex [Cp(CO)Fe{μ₂-η¹(C_α):η¹(C_α)-κ¹(N)-C_α Created by potrace 1.16, written by Peter Selinger 2001-2019 ]]> C_β(H)(o-C₅H₄N)}(μ-CO)PdI]. The conditions, catalysts, and reagents that provide the highest yields of the desired σ-pyridylethynyl iron compounds were determined. The methods developed allowed the synthesis of the corresponding σ-4-benzothiadiazolylethynyl complex Cp(CO)₂Fe–CC–(4-C₆H₃N₂S) as well. Eventually, synthetic approaches to σ-alkynyl iron complexes of the type Cp(CO)₂Fe–CC–R (R = ortho-, meta-, para-pyridyl, 4-benzothiadiazol-2,1,3-yl) based on the Pd/Cu-catalyzed cross-coupling reactions were elaborated.

Two approaches were developed for the synthesis of iron σ-pyridylethynyl complexes based on Pd/Cu- and Pd-catalyzed Fe–C coupling reactions.

Synthesis and characterisation of halide, separated ion pair, and hydride cyclopentadienyl iron bis(diphenylphosphino)ethane derivatives

The synthesis and structures of 25 halide, separated ion pair, and hydride cyclopentadienyl iron bis(diphenylphosphino)ethane complexes are described.

Binuclear ruthenium η6-arene complexes with tetradentate N,S-ligands containing the ortho-aminothiophenol motif

A series of cationic binuclear (η(6)-cymene-Ru)2 complexes with N2S2-ligands were synthesized in 64% to 85% yield by reaction of [Ru(η(6)-cymene)Cl2]2 with bis-S,S'-(ortho-aminothiophenol)-xylenes as BF4(-) and PF6(-) salts. The compounds were studied using NMR, HRMS, UV-vis and IR spectroscopy, EA and inductively coupled plasma (ICP) MS. It was determined that the hinged binuclear Ru complexes were anti and syn diastereomers obtained in 2 : 1 ratio for ortho- and meta-xylylene bridged ligands and in a 1 : 1 ratio for the para-xylylene bridged ligand. An anion effect was found for the presence of NaBF4 with the meta-xylylene bridged system yielding the targeted binuclear Ru complex and a mononuclear Ru complex. This mononuclear S,S'-coordinated η(6)-cymene Ru chloride structure lacked amine-metal coordination and was obtained in a 1 : 3 ratio of anti : syn diastereomers which were insoluble in CH2Cl2 and soluble in DMSO and DMF. X-ray crystallographic analysis was obtained for the N2S2 ligand, 1,2-bis{(2-aminophenyl)thiomethyl}benzene, showing a CS symmetry with amine groups facing outwards with a tilt of 28.95° from the ortho-aminothiophenol pendant ring. The interatomic sulfur-sulfur distance (S-S') is 4.6405 Å within the crystal structure while accommodating a potential metal bite angle from 1.0 Å to 5.9 Å when allowing rotation of the methylene phenyl bond.

Wirelike Dinuclear Ruthenium Complexes Connected by Bis(ethynyl)oligothiophene

Preparation and characterization of a series of rodlike binuclear ruthenium polyynediyl complexes capped with redox-active organometallic fragments [(bph)(PPh3)2Ru]+ (bph=N-(benzoyl)-N'-(picolinylidene)-hydrazine) or [(Phtpy)(PPh3)2Ru]2+ (Phtpy=4'-phenyl-2,2':6',2' '-terpyridine) have been carried out. The length of the molecular rods is extended by successive insertion of 2,5-thiophene or 1,4-phenylene spacers in the bridging ligands. Oxidation of thiophene-containing Ru2II,II complexes induces isolation of stable Ru2II,III or Ru2III,III species. Electrochemical and UV-vis-NIR spectral studies demonstrate that the polyynediyl bridges with 2,5-thiophene units are more favorable for metal-metal charge transfer compared with those containing the same number of 1,4-phenylene units. Successive increase of thiophene spacers in mixed-valence complexes {RuII}-CC(C4H2S)mCC-{RuIII} (m=1, 2, 3) induced a smooth transition from almost electronic delocalization (m=1) to localization (m=3). For binuclear ruthenium complexes with intramolecular electron transfer transmitted across nine Ru-C and C-C bonds, electronic conveying capability follows {Ru}-CC(CC)2CC-{Ru}>{Ru}-CC(C4H2S)CC-{Ru}>{Ru}-CC(C6H4)CC-{Ru}>{Ru}-CC(CH=CH)2CC-{Ru}. It is revealed that molecular wires capped with electron-rich (bph)(PPh3)2Ru endgroups are much more favorable for electronic communication than the corresponding electron-deficient (Phtpy)(PPh3)2Ru-containing counterparts. The intermetallic electronic communication is fine-tuned by modification of both the bridging spacers and the ancillary ligands.