Chromium Tricarbonyl η6-Complexes of (η5-Cyclopentadienyl)(η4-1,3-Diphenylcyclobutadiene)Cobalt

The reaction of (η⁵-cyclopentadienyl)(η⁴-1,3-diphenylcyclobutadiene)cobalt ( I ) with excess Cr(CO)₃py₃ in BF₃OEt₂ yielded two identified heterometallic compounds. Compounds II and III with one and two phenyl rings complcxed with Cr(CO)₃ fragment(s), respectively. These compounds were characterized by mass, infrared, ¹H and ¹³C NMR spectra and elemental analysis. The crystal structure of II was determined. The Cr(CO)₃ fragment bends inward toward the cyclobutadicne ring due to its electron-withdrawing ability, in accord with Hunter's postulate. A sharp line due to the non-complexed phenyl ring was observed in the ¹HNMR spectrum, which implies that five protons are magnetically equivalent. The chemical shifts of two protons of the cyclobutadiene ring decreased from I to II then to III , possibly because of diminished deshielding effect from the phenyl ring in (arene)Cr(CO)₃.     

η-Pentamethylcyclopentadienylruthenium(II) complexes containing η-coordinated α-amino acids

Reaction of [Cp* RuCl₂]₂ with -alanine ( -alaH) in methanol at room temperature in the presence of NaOMe yields the complex Na[Cp* RuCl( -ala)] (1), which contains a five-membered N,O-coordinated chelate ring. The analogous complex Na[Cp* RuCl( -phe)] (2) is obtained under similar conditions but at 0°C in 90% yield. At temperatures above 20°C both 2 and the η⁶-coordinated complex [Cp* Ru( -pheH)]Cl (4) are obtained, with the proportion of the latter increasing with temperature. Compound 4 is obtained in 88% yield by refluxing [Cp* RuCl₂]₂ and -phenylalanine ( -pheH) in CH₃OH/CH₃ONa followed by separation from 2. The analogous ruthenium(II) sandwich complexes 5–10 were obtained from -tyrosine and -tryptophane and various derivatives. [Cp* Ru( -met)] (3), prepared by the reaction of [Cp* RuCl₂]₂ with -methionine ( -metH) in CH₃OH/CH₃ONa, displays N,O,S-coordination.     

Crystal and molecular structures of (η-xanthene)- (η-cyclopentadienyl)iron(II) hexafluorophosphate and (η-2-methylthianthrene)(η-cyclopentadienyl)iron(II) hexafluorophosphate

The neutral complexes (η⁵-C₅H₅NiXL (X = Cl, L = PPh₃ (I); L = PCy₃ (II); X = Br, L = PPh₃ (III); L = PCy₃ (IV); X = I, L = PPh₃ (V); L = PCy₃ (VI)) have been obtained by treating NiX₂L₂ with thallium cyclopentadienide. The same reaction in the presence of TlBF₄ gives cationic derivatives [(η⁵-C₅H₅)NiL₂]BF₄ (L = 2PPh₂Me (VII); L = dppe (VIII)), whereas mononuclear complexes containing two different ligands (L₂ = PPh₃ + PCy₃ (IX)) or dinuclear [(η⁵-C₅H₅)Ni(PPh₃)]₂dppe(BF₄)₂ (X) are obtained from the reaction of III with TlBF₄ in the presence of a different ligand. Reduction of cationic complexes with Na/Hg gives very unstable nickel(I) derivatives (η⁵-C₅H₅)NiL₂, which could not be isolated purely. Similar reduction of neutral complexes under CO gives a mixture of decomposition products containing [(η⁵-C₅H₅)Ni(CO)]₂ and nickel(o) carbonyls, whereas in the presence of acetylenes, dinuclear [(η⁵-C₅H₅)Ni]₂(RCCR′) (R = R′ = Ph; R = Ph, R′ = H) are obtained.     

(η5‐Cyclopentadienyl)(η6‐phenoxathiin 10,10‐dioxide)iron(II) hexafluoridophosphate and phenoxathiin 10,10‐dioxide

In the structure of the title complex salt, [Fe(C₅H₅)(C₁₂H₈O₃S)]PF₆, the coordinated cyclopentadienyl (Cp) and benzene ring planes are almost parallel, with a hinge angle between the planes of 0.8 (2)°. The hinge angle between the planes of the peripheral (coordinated and uncoordinated) benzene rings in the coordinated phenoxathiin 10,10‐dioxide molecule is 169.9 (2)°, and the FeCp moiety is located inside the shallow fold of the heterocycle. The hinge angle between the benzene ring planes in the free heterocycle, C₁₂H₈O₃S, is 171.49 (6)°.     

(η6‐Hexamethylbenzene)(mesidine)­ditriflatoruthenium(II)

The crystal structure of the title complex, (η⁶‐hexamethylbenzene)bis(trifluoromethanesulfonato‐O)(2,4,6‐trimethylanil­ine‐N)ruthenium(II), [Ru(CF₃O₃S)₂(C₁₂H₁₈)(C₉H₁₃N)], is described. The complex has the classic three‐legged piano‐stool structure with a planar arene 1.667 Å from the metal, two monodentate O‐bound tri­fluoro­methane­sulfonate ligands [Ru—O 2.169 (2) and 2.174 (2) Å] and one N‐bound mesidine ligand [Ru—N 2.198 (2) Å]. The Ru—N distance is relatively long and the average Ru—O distance is relatively short when compared with previously characterized Ru^II complexes.     

Three ruthenocene derivatives: (η5‐4,7‐dimethylindenyl)(η5‐pentamethylcyclopentadienyl)ruthenium(II), [η5‐[2](4,7)indeno[2]paracyclophanyl](η5‐pentamethylcyclopentadienyl)ruthenium(II) and bis[η5‐[2](4,7)indeno[2]paracyclophanyl]­ruthenium(II)

In the title compounds, [Ru(C₁₀H₁₅)(C₁₁H₁₁)], (III), [Ru(C₁₀H₁₅)(C₁₉H₁₇)], (IV), and [Ru(C₁₉H₁₇)₂], (V), respectively, the coordinating ring systems are planar and parallel, with the Ru atoms lying at perpendicular distances of Ru–Cp* 1.790 (1) Å and Ru–indenyl 1.836 (1) Å in (III), Ru–Cp* 1.791 (1) Å and Ru–indenyl 1.837 (1) Å in (IV), and Ru–indenyl 1.812 (1) Å and 1.809 (1) Å in (V) (Cp* is penta­methyl­cyclo­penta­dienyl). The ring conformations are eclipsed for (III), staggered for (IV) and intermediate for (V). All three compounds show short intermolecular contacts from C—H groups to some ring centroids; these could be regarded as C—H?π hydrogen bonds. The mol­ecules of each compound are thus connected via the 2₁ screw axis to form layers parallel to the xy plane.