Quantum mechanical calculations on the model compounds [Fe(ECH 3 ) 5 ] (E = Al, Ga, In) suggest the existence of the homoleptic, trigonal-bipyramidal d 8 metal complexes of the exotic ligands E

Two routes are described for the synthesis of (η4-1,5-cyclooctadiene)(η6-phosphinine)iron(0) complexes. A three-component reaction of iron vapor with COD and 2-(trimethylsilyl)-4,5-dimethylphosphinine at low temperature yields 20% (COD)(2-(trimethylsilyl)-4,5-dimethylphosphinine)Fe(0) (3), whereas ligand exchange of one COD ligand of the in situ prepared metal vapor product (COD)2Fe by 2-(trimethylsilyl)-4,5-dimethylphosphinine or (η1-2-chloro-4,5-dimethylphosphinine)Cr(CO)5 gives corresponding (COD)(phosphinine)Fe(0) complexes in more than 80% isolated yield. As the phosphinine derivatives are prochiral, complexation leads to the racemate of two enantiomers. Both enantiomers are found in the unit cell of single crystalline 3 and are related by an inversion center. Complex 3 is a novel room-temperature catalyst for the [2 + 2 + 2] cyclic addition reaction of one molecule of butyronitrile with two molecules of methyl propargyl ether giving up to 160 mol of pyridine derivatives/mol 3. A chemically robust species, 3 is an air-stable crystalline material, but exposure to oxygen in solution causes slow decomposition.

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The reaction of Na[3,5-di-(tert-butyl)-1,2,4-triphospholyl] (Na-2) with R 3 SnCl (R Ph, Me, nBu) affords the 1-triorganylstannyl-3,5-di(tert-butyl)-1,2,4-triphospholes 4 a ± 4 c in very good yields. A rapid suprafacial [1,5]-sigmatropic shift of the SnPh 3 group in 4 a with DG = 31.5 kJ mol À1 indicates a labile

The easily accessible (R)-3-phenylbutanol (1) can be transformed into the novel enantiopure ligand diphenyl((R)-3-phenylbutyl)phosphane (3). 3 splits the complex dimer [{RuCl 2 (η 6 -C 6 H 5 CO 2 Me)} 2 ] (6) by adding as a σ-ligand to form mononuclear [RuCl 2 (η 6 -C 6 H 5 COOMe)-((R)-η 1 -PPh 2 (CH 2 ) 2 CH(CH 3 )Ph)] ( 7). An intramolecular arene ligand displacement reaction leads to [RuCl 2 ((R)-η 1 -PPh 2 (CH 2 ) 2 CH(CH 3 )-η 6 -C 6 H 5 )] ( 8) with a tethered side chain of the arene ligand. Nucleophilic substitution of a chloride ligand by primary or secondary amines with the assistance of NaBF 4 gives access to the diastereomeric complex salts [RuCl(amine)-((R)-η 1 -PPh 2 (CH 2 ) 2 CH(CH 3 )-η 6 -C 6 H 5 )]BF 4 . Good diastereoselectivities were obtained for aniline, piperidine, benzylamine, and butylamine complex salts 9-12 (de ) 82-90%). The absolute structures of 8-10 have been determined by X-ray structure analysis. S Ru ,R C configurations were found for the major diastereomers of aniline and piperidine complex salts 9 and 10. Not only the side chain stereogenic center but also the metal configuration of the cation of salt 9 is stable for longer periods at low and at elevated temperatures in different solutions.