Five-carbon-donor Ligands

Complexes with Five-carbon-donor Ligands. Three w-cyclopentadienyl-dicarbonyliron complexes have been investigated. They all contain an iron atom in a distorted octahedral environment, with the terdentate (w-CsHg) 

In the [Fe(C0)i(C9H80)l complex (34) the asymmetrically substituted cyclohexadienyl ligand is linked to the iron atom by means of a n bonded pentadienyl group and a a-bonded propenoyl side-chain. The iron atom 

Cluster Complexes. The molecular geometry of the [Fej(CO),(PMe2Ph)3] cluster (35) is closely similar to that of [Fes(CO)i2] the isosceles triangle of iron atoms, with the shortest side bridged by two carbonyl groups, is 

The [Fei3(CO)x (NSiMej,)] molecule (36) has approximate Cs symmetry and contains triply bridging carbonyl and trimethylsilylimino-groups.  

The hexanuclear iron cluster (37) in the salt [Me4N]s[Fe (CO)uC] is regarded as the first known anionic carbidocarbonyl complex of any metal,  

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Carbon monoxide binds weakly as a cr-donor ligand to four-coordinate co-balt(II) systems. Despite a bout of artifactual excitement, CO has never been observed to bind significantly to five-coordinate Co systems with a nitrogenous axial base to yield octahedral six-coordinate species. - The sulfur analogue thiocarbonyl (CS), although not stable as a free entity, binds very strongly to iron-porphyrin species in a linear manner. ... 

A similar complex with ethanthiolate ligands has been obtained by conventional synthetic strategies.The overall structural principles of this complex type can be described as follows. The metal-ligand framework is a trigonal prism with corners defined by the five sulfur donor functions of the isopropanethiolate ligands and one carbon atom of a CO ligand. The metal atoms are shifted from the centers of the... 

A series of l-(pyridin-2-yl)benzimidazolium salts were synthesized by Chianese et al. and used as precursors to rigid, five-membered chelated biden-tate NHC-pyridine ligands [57]. The ligands were constructed with either very small (H, Me) or very bulky (2,6-diisopropylphenyl, 2,4,6-triisopropylphenyl) groups adjacent to the nitrogen and carbon donor atoms. Cationic palladium-allyl complexes were synthesized under mild conditions and used as catalysts for the allylic substitution reaction between allylic carbonates and either sodium dieth)f-2-methylmalonate or Af-methylbenzylamine. 

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