Synthesis and investigation of mono- and binuclear cyano-bridged complexes of rhodium,ruthenium, and palladium

Binuclear Rh^III and Ru^II complexes of the [M¹-CN-M²]⁺BF ₄ ^– (M¹ and/or M² are (⁵-Cp)(³-C₃H₅)Rh and (⁶-C₆H₆)(³-C₃H₅)Ru) type, heteronuclear organometallic compound (⁵-Cp)(³-C₃H₅)RhCNPd(³-C₃H₅)Cl, and mononuclear Rh^III and Ru^II complexes [(³-C₃H₅)LM(MeCN)]⁺ _BF4 ^– (M = Rh, L = ⁵-Cp; M = Ru, L = ⁶-C₆H₆) were synthesized. An electrochemical study of these compounds in solutions demonstrates that the bond between the bridged CN ligand and the metal atoms is rather strong, and there is no dissociation into mononuclear fragments in solutions. The kinetics of the reaction of [(⁵-Cp)(³-C₃H₅)Rh(MeCN)]⁺ _BF4 ^– with halide ions was studied by electrochemical methods. The ligand exchange proceeds by a bimolecular dissociative-exchange mechanism.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 968–973, May, 1995.     

Investigation of the redox properties of polynuclear “ladder” complexes containing Cr,Mn, and Fe

The redox potentials of new Cr, Mn, and Fe polynuclear ladder complexes, (⁵-Cp)Fe(CO)₂(¹,⁵-C₅H₄)Fe(CO)₂(¹,⁵-C₅H₄)Mn(CO)₃, (⁵-Cp)Fe(CO)₂(¹,⁵-C₅H₄)Mn(CO)₃, (⁵-Cp)Fe(CO)₂(¹,⁶-Ph)Cr(CO)₃, (⁵-Cp)Fe(CO)₂(¹,⁵-C₅H₄)Fe(CO)₂CH₂Ph, (⁵-Cp)Fe(CO)₂(¹,⁶-CH₂Ph)Cr(CO)₃, were measured and the mechanism of their electrochemical oxidation and reduction was suggested. It was shown that the - or -bonds of the bridging ligand can be cleaved selectively by applying cathodic or anodic potentials, respectively. On the basis of the obtained electrochemical data, a mechanism is suggested for the rearrangement observed when the complexes are metallated by butyllithium.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 362–366, February, 1995.This work was carried out with financial support from the Russian Foundation for Basic Research (Project No 94-03-08628a).     

Synthesis,characterization and crystal structures of heterometallic trinuclear carbonyl sulfido clusters (η5-Cp)MoFeCo- (CO)8(μ3-S) and [(η5-Cp)Mo]2Fe(CO)7(μ3-S)

HFe2Co(CO)9(3-S) reacts with (5-Cp)Mo(CO)3Cl in refluxing THF to give heterometallic trinuclear clusters (5-Cp)MoFeCo(CO)8(3-S) and [(5-Cp)Mo]2Fe(CO)7-(3-S), which have been characterized by elemental analyses, i.r., 1H- and 13C-n.m.r. and X-ray crystal structure determination. An electrophilic addition–elimination sequence is proposed for their formation.     

Four novel classes of heterobimetallic isopropoxides of chromium(III)

Four novel classes of hydrocarbon-soluble isopropoxometallates of chromium(III): [Cr{²-Zr(OPr ⁱ )₅}₃], [Cr- {²-M₂(OPr ⁱ )₉}₃] [M = Zr^IV, Sn^IV], [Cr{²-M(OPr ⁱ ) _x Cl}₃] (M = Al, x = 3; M = Nb, x = 5), and [Cr{⁴-Zr₂-(OPr ⁱ )₈Cl}Cl₂]/[Cr{³-Zr₂(OPr ⁱ )₈Cl}{²-Zr₂(OPr ⁱ )₈Cl}Cl] [ ⁿ represents the number of connectivity sites (n = 2, 3, 4) involved in binding Cr^III] have been prepared for the first time and characterized by the elemental analyses, spectroscopic (i.r., electronic) and magnetic susceptibility studies as well as molecular weight measurements. The [Cr{²-Ga(OPr ⁱ )₄}₃] derivative has also been prepared and its magnetic and electronic properties compared with the above four novel types of Cr^III complexes.     

First metal complex with the azulene dianion. Molecular structure of the (2η1:η2-Gaz)Lu(η5-Cp)(DME) complex (Gaz is 7-isopropyl-1,4-dimethylazulene)

The metallocene derivative (2¹:²-Gaz)Lu(⁵-Cp)(DME) (1) (Gaz is 7-isopropyl-1,4-dimethylazulene) was prepared by reduction of guaiazulene with the lutetium naphthalene complex (⁵-Cp)Lu(2¹:²-C₁₀H₈)(DME) in 1,2-dimethoxyethane (DME). Complex 1 crystallized from a solution as blue crystals. According to the results of X-ray diffraction analysis, molecule 1 has a skewed pseudo-sandwich structure in which the Lu atom is ⁵-coordinated by the cyclopentadienyl ring and 2¹:²-coordinated by the seven-membered ring of the guaiazulene ligand. The coordination sphere of the metal atom in complex 1 is completed with the chelating DME molecule.     

Inter-ring η6⇌η5 haptotropic rearrangements of 18ē and 19ē (η5-pentamethylcyclopentadienyl)(η6-9-methylfluorenyl)iron complexes

New cationic complexes [(⁶-C₁₃H₁₀)Fe(⁵-Cp^*)]PF₆ and [(⁶-9-CH₃-C₁₃H₉)Fe(⁵-Cp^*)]PF₆ were obtained by the reaction of Cp^*Fe(CO)₂Br with fluorene and 9-methylfluorene, respectively. Deprotonation of these complexes byt-BuOK in THF affords zwitter-ionic compounds (⁶-C₁₃H₉)Fe(⁵-Cp^*) and (⁶-9-CH₃-C₁₃H₈)Fe(⁵-Cp^*) (A). WhenA is heated in nonane at 150 °C it undergoes ⁶⁵ inter-ring rearrangement with the formation of hexamethyldibenzoferrocene (B). The electrochemical behavior ofA andB was studied by cyclic voltammetry. One-electron reduction ofA andB to the corresponding radical anions induces inter-ring haptotropic rearrangementA ^.–B ^.–. The equilibrium in the 19 state is shifted to the ⁶-isomeric radical anionA ^.–, while in the 18 precursors, it shifts to the ⁵-isomerB.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 319–324, February, 1994.The authors are grateful to D. V. Zagorevskii (A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences) for recording and interpreting the mass spectra, and to A. A. Borisenko (Moscow State University) for recording the NMR spectra.This work was financially supported by the Russian Foundation for Basic Research (Grant 93-03-5209).     

The mechanism of η(η5:η5-fulvalene)-di-μ-chloro-bis (η5-cyclopentadienyltitanium) formation in the system Cp2TiCl2 : LiAlH4 : Olefinic solvent

Summary The reduction of Cp₂TiCl₂ with LiAlH₄ in olefinic solvents at temperatures above 100° leads to the formation of µ-( ⁵ : ⁵-fulvalene)-di-µ-chloro-bis( ⁵-cyclopentadienyl-titanium) (1) and finally to µ-( ⁵ : ¹⁵-fulvalene)-di-µ-hydrido-bis ( ⁵-cyclopentadienyltitanium). The first step of the reduction includes mainly the formation of the dimer of bis( ⁵-cyclopentadienyl)titanium(III) chloride, (Cp₂TiCl)₂. The mechanism of its conversion into (1) involves the formation of an intermediate bis( ⁵-cyclopentadienyl)titanium(III) hydride species which reacts immediately with the olefinic solvent to give bis( ⁵-cyclopentadienyl)alkyltitanium(III) compounds. The formation of the fulvalene ligand in (1) is explained by the interaction of the alkyltitanium compound with the cyclopentadienyl ligands of (Cp₂TiCl)₂ resulting in hydrogen transfer to the olefinic solvent.     

Reaction of ruthenium carbonylcarbide cluster Ru6C(CO)17 with nickelocene and pentamethylcyclopentadiene

The reaction of cluster Ru₆C(CO)₁₇ (1) with nickelocene is studied. Five CO ligands rather than a metal-ligand crown are substituted for two cyclopentadienyl groups to give a new complex Ru₆C(⁵-Cp)₂(CO)₁₂ (2). The reaction of cluster1 with entamethylcyclopentadiene leads to new complex Ru₆C(-¹⁵-CH₂C₅Me₄)(CO)₁₄ (3) containing the cr-bond CH₂-Ru, along with an ⁵-coordinated cyclopentadienyl ring.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1171–1172, June, 1995.     

Novel tetrahedral and heteronuclear transition metal clusters prepared via single and double isolobal displacements

Ten transition metal cluster complexes with parent and substituted cyclopentadienyl ligands, [(⁵-C₅H⁴ CH₂CH₂)₂O][MFeCoS(CO)₈]₂ (2 M=Mo; 3 M=W), (⁵-C₅H₅)(⁵-RC₅H₄)MFeNiS(CO)₅ (5 M=Mo, R=Me; 6M= W, R=H), (⁵-C₅H₅)[⁵-C₅H₄C(O)CH₂]₂[WFeNiS(CO)₅][WFeCoS(CO)₈] (8), (⁵-C₅H₅)₂[⁵-C₅H₄ C(O)CH₂]₂[WFeNiS(CO)₅]₂ (9), (⁵-RC₅H₄)[(⁵-C₅H₄CH₂CH₂)₂O][Mo2FeS(CO)₇][MoFeCoS (CO)₈] (10R=MeCO; 12 R=MeO2C), (⁵-RC₅H₄)₂[(⁵-C₅H₄CH₂CH₂)₂O][Mo₂FeS(CO)₇]₂ (11 R=MeCO; 13 R=MeO2C), were synthesized through single and double isolobal displacements and characterized by elemental analyses, i.r., 1H-n.m.r. and MS techniques.     

η-Cyclopentadienyl(nitrosyl)iron complexes containing group VA donors

Summary [(-C₅H₅)Fe(NO)(CO)]₂ and (-C₅H₅)Fe(NO)(CO)I are formed when a slow stream of NO is passed through a benzene solution of [(-C₅H₅)Fe(CO)₂]₂ and (-C₅H₅)Fe(CO)₂ I respectively. Similarly NO reacts with (-C₅H₅)Fe(CO)(Ph₃E)I and [(-C₅H₅)Fe(CO)₂(Ph₃E)]I, where E = P, As and Sb, to give (-C₅H₅)Fe(NO)(Ph₃E)I and [(-C₅H₅)Fe(NO)₂(Ph₃E)]I respectively. The complexes were characterized by elemental analyses and i.r. spectra.Reprints of this article are not available.     

The reactions of [Fe2(η-Cp)2(CNAr)4] complexes with halogens and tin(II) halides

Summary [Fe₂(-Cp)₂(CNAr)₄] (2) (540-01, C₆H₄Me-2, C₆H₄Et-2, C₆H₃Me₂-2,4, C₆H₃Me₂-2,6, C₆H₃(Me)Et-2,6, C₆H₃Et₂-2,6 or C₆H₃ i-Pr₂-2,6) react with I₂ to give [Fe(-Cp)(CNAr)₂I], but with Br₂[Fe(-Cp) (CNAr)₃]⁺ salts are the only products; IBr gives a mixture of the two. With SnX₂ (X = F, Cl, Br or I) in refluxing n-butanol, (2) gives isolable [{Fe(-Cp)(CNAr)₂}₂SnX₂] only when the CNAr ligands have two ortho substituents, otherwise decomposition occurred. When X = F, [Fe(-Cp) (CNAr)₂SnF₃] was also obtained from this reaction. Attempts to prepare [Fe(-Cp)(CNAr)₂X] (X = Cl or Br) by reaction of (2) with HX in the presence of air gave rather unstable products which with SnX₂ formed [Fe(-C₅H₅)-(CNAr)₂SnX₃]. Similar compounds, [Fe(-Cp) (CNAr)₂ SnX₂I], were obtained from [Fe(-Cp)-(CNAr)₂I] and SnX₂ (X = Cl or Br but not I). All of these complexes are much less stable than their Fe(-Cp)(CO)₂ counterparts; all decompose in solution to [Fe(-Cp)(CNAr)₃]⁺ which then break down to unidentified species. X-ray diffraction studies show that in [Fe(-Cp)(CNC₆H₃-i-Pr₂-2,6)₂I] and [{Fe(-Cp)(CNC₆H₃Me₂-2,6)₂}₂SnBr₂] there is pseudo-octahedral coordination about Fe. In the latter there is also distorted tetrahedral coordination about Sn so that its structure is very similar to that of [{Fe(-Cp)(CO)₂}₂SnCl₂]. Spectroscopic studies show that in all complexes rotation of the aryl rings of the CNAr ligands cannot be slowed in solution, and that there is free rotation about all 540-02 bonds.     

Synthesis and spectroscopic studies of complexes containing the Schiff base 1-acetylferrocene(thio)semicarbazone

Summary [RuCl₂(CO)₂] _n reacts with the Schiff base 1-acetylferrocenethiosemicarbazone, [Fe(-Cp)(-C₅H₄MeC=NN-HCSNH₂)] to give [Fe(-Cp)(-C₅H₄MeC=NN-HCSNH₂)RuCl₂(CO)₂] and with 1-acetylferrocenesemicarbazone [Fe(-Cp)(-C₅H₄MeC=NN-HCSNH₂)] to give [Fe(-Cp)(-C₅H₄MeC=NN-HCSNH₂)RuCl₂-(CO) ₂]. Spectroscopic data indicate that the Schiff bases act as bidentate ligands and coordinate to ruthenium via the hydrazinic N and either the S or O atoms, respectively, giving stable heterobimetallic complexes, which have been characterized by i.r. and ¹H-n.m.r. spectroscopies, and elemental analyses.Part of this work was presented at the First International Conference in Chemistry and its applications in Doha, Qatar, 1993.     

Formation,properties, and thermal decomposition of bisarene chromium(i) and molybdenum(i) fullerides

Fullerides [(⁶-Ph₂)₂Cr]⁺[C₆₀]^·–, [(⁶-C₁₀H₁₂)₂Cr]⁺[C₆₀]^·– (C₁₀H₁₂ is tetralin), and [(⁶-PhCH₃)₂Mo]⁺[C₆₀]^·– were synthesized. The molecular structure of [(⁶-Ph₂)₂Cr]⁺[C₆₀]^·– was established. In this compound at 100 K, radical anions C₆₀ ^–· are linked by an ordinary bond to form dimers, whereas at 293 K they are disordered and do not form dimers. The [(⁶-tetralin)₂Cr]⁺[C₆₀]^·– fulleride is stable in vacuo (10^–2 Torr) below 429 K, and [(⁶-toluene)₂Mo]⁺[C₆₀]^·– is stable below 581 K.Based on the materials presented at the International Conference Modern Trends in Organoelement and Polymer Chemistry (Moscow, May 30–June 4, 2004) dedicated to the 50th anniversary of the A. N. Nesmeyanov Institute of Organoelement Compounds of the Russian Academy of Sciences.Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1973–1976, September, 2004.     

The catalytic system [(Cp2TiCl)2]:LiAlH4 in aromatic solvents,Part II. Formation of η3-allyltitanocene derivatives in the presence of dienes — their structure and e.s.r. spectra

Summary The addition of dienes to the system [(Cp₂TiCl)₂] LiAlH₄toluene changes the system so that the complex [Cp₂TiAlH₄] is quantitatively formed instead of a titanocene hydride — aluminium hydride cluster. The complex [Cp₂TiAlH₄] is further converted into ³-allyltitanocene derivatives ([Cp₂TiA]) if the diene structure is suitable for formation of stable [Cp₂TiA] compounds and if the equilibrium [Cp₂TiAlH₄]+diene[Cp₂TiA]+A1H₃ is shifted towards the formation of [Cp₂TiA] by the excess of diene. All the compounds [Cp₂TiA] exhibit high-resolution e.s.r. spectra at g=1.993, showing interaction of the unpaired electron with the cyclopentadienyl and ³-allyl protons. The e.s.r. spectra clearly reveal the presence of alkyl substituents atsyn-1,3-positions of ³-allyl ligand, and show a triplet of multiplets for (³-allyl)titanocene, doublets of multiplets for (1-alkyl-³-allyl)titanocenes and single multiplets for (1,3-dialkyl-³-allyl)-titanocenes. thermal isomerization of (1,3-dimethyl-³-allyl)-titanocene and (1-methyl-3-ethyl-³-allyl)titanocene, hitherto considered as the stable Cp₂TiA compounds, into (1-alkyl-³-allyl)titanocenes was confirmed by e.s.r. and electronic absorption spectroscopy as well as by chemical means.     

Study of Redox-induced Reactions of Vinylidene and bis-Vinylidene Complexes of Manganese

Oxidative dehydrodimerization of some phenylvinylidene complexes of manganese is studied by cyclic voltammetry. In the case of (⁵-C₅H₅)(CO)₂Mn=C=C(H)Ph, the process occurs as the homolysis of the C–H bond in the radical cation of {(⁵-C₅H₅)(CO)₂Mn=C=C(H)Ph}^+· and the dimerization of intermediate -phenylethinyl cation [(⁵-C₅H₅)(CO)₂Mn–CC–Ph]⁺ to a binuclear dication of bis-carbine type (⁵-C₅H₅)(CO)₂Mn⁺C– C(Ph)=C(Ph)–CMn⁺(CO)₂(⁵-C₅H₅). The reduction of the latter leads to binuclear bis-vinylidene complex (⁵-C₅H₅)(CO)₂Mn=C=C(Ph)–C(Ph)=C=Mn(CO)₂(⁵-C₅H₅). Oxidative dehydrodimerization of complexes (⁵-C₅R₅)(CO)(L)Mn=C=C(H)Ph (R = H, L = PPh₃; R = Me, L = CO) occurs through the immediate C–C coupling of radical cations {(⁵-C₅R₅)(CO)(L)Mn=C=C(H)Ph}^+· and yields binuclear dication bis-carbine complexes (⁵-C₅R₅)(CO)(L)Mn⁺C–C(H)(Ph)–C(H)(Ph)–CMn⁺(CO)(L)(⁵-C₅R₅), whose reduction leads to neutral compounds (⁵-C₅H₅)(CO)₂Mn=C=C(Ph)–C(Ph)=C=Mn(CO)(L)(⁵-C₅H₅). Complex (⁵-C₅H₅)(CO)₂Mn=C=C(Ph)–C(Ph)=C=Mn(CO)₂(⁵-C₅H₅) undergoes the oxidation-induced nucleophilic addition of water, forming cyclic bis-carbene product with a bridge heterocyclic ligand (-3,4-diphenyl-2,5-dihydro-2,5-diylidene)-bis-(⁵-cyclopentadienyldicarbonyl manganese).     

Tricarbonylbis(η-cyclopentadienyl)diiron and iododicarbonyl(η-cyclopentadienyl)iron amine complexes

Summary The monodentate ligands, L, ethylamine, butylamine, cyclohexylamine, benzylamine, piperidine and morpholine, and bidentate ligands, L, 1,10-phenanthroline and 2,2-bipyridyl react with tetracarbonylbis(-cyclopentadienyl)diiron to give monosubstituted derivatives, (-C₅H₅)₂Fe₂(CO)₃L, and with iododicarbonyl(-cyclopentadienyl)iron to yield ionic products, [(-C₅H₅)Fe(CO)₂L]I. I.r. spectral studies suggest that two isomeric (-C₅H₅)₂-Fe₂(CO)₃L molecules exist.     

The viscosity of aqueous solutions of alkali and tetraalkylammonium halides at 25°C

The viscosities of most alkali and tetraalkylammonium halides have been measured in water at 25°C. The relative viscosities can be fitted, up to 1M, with the relation _r =1+A c^1/2+B c+D ². TheA term depends on long-range coulombic forces, andB is a function of the size and hydration of the solute. When combined with partial-molal-volume data, the difference B –0.0025V° is mostly a measure of the solute-solvent interactions. IonicB are obtained if the tetraethylammonium ion is assumed to obey Einstein's law. TheD parameter depends on higher terms of the long-range coulombic forces, on higher terms of the hydrodynamic effect, and on structural solute-solute interactions. As such, it cannot be interpreted unambiguously.     

Synthesis and crystal structure of [(η3-C3H5)(CO)2Mo(μ-S2CPCy3)-Mo(η3-CH2CMeCH2)(CO)2]

A novel dimolybdenum complex [(³-C₃H₅)(CO)₂Mo(-S₂CPCy₃)Mo(³-CH₂CMeCH₂)(CO)₂], obtained by reacting the [(CO)₂(³-C₃H₅)Mo(-S₂CPCy₃)Mo(CO)₃]^– anion with an excess of ClCH₂CMe=CH₂, has been characterized by i.r., ³¹P{¹H}, ¹H- and ¹³C-n.m.r. spectroscopy and by elemental analysis. The crystal structure of the complex, determined by X-ray diffraction, shows a definite preference for the central carbon of the S₂CPCy₃ bridge to bind to the Mo(2) atom coordinated by ³-2-methylallyl, rather than the Mo(1) atom attached to unsubstituted ³-allyl ligand.     

Oxidation of isomeric η6- and η5-fluorenylchromiumtricarbonyl anions

The oxidation of the carbon-centered [(⁶-C₁₃H₉)Cr(CO)₃]^– anion (1 ^–) results in formation of (-⁶:⁶-9,9-bifluorenyl)bis-chromiumtricarbonyl (3) due to coupling of the intermediate carbon-centered radical (1^.). The oxidation of the metal-centered anion [(⁵-C₁₃H₉)Cr(CO)₃]^– (2 ^–), which is isomeric to the 1^– anion, gives an equilibrium mixture of the chromium-centered radical {(⁵-C₁₃H₉)Cr(CO)₃}^. (2 ^.) and its dimer [(⁵-C₁₃H₉)Cr(CO)₃]₂ (6). Radical2 ^. readily reacts with MeI and the solvent (THF); the resulting derivatives, (⁵-C₁₃H₉)Cr(CO)₃R (R=Me (10); R=H (7)), undergo fast ricochet inter-ring ⁵⁶ rearrangements into (⁶-9R-C₁₃H₉)Cr(CO)₃ (R=CH₃ (9); R=H (4)).Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 7, pp. 1354–1358, July, 1995.The authors are grateful to D. V. Zagorevskii who recorded the mass spectra. This study was financially supported by the Russian Foundation for Basic Research (Grant No. 94-03-05209) and the International Science Foundation (Grant Nos. MQ 4000 and REV 000).     

Electrochemical Properties of the Sandwich and Carbonyl π-Complexes of Chromium with Fluoranthene

Redox properties of mono- and binuclear -complexes of Cr with fluoranthene with the composition of (⁶-C₁₆H₁₀)Cr(⁶-C₆H₆), (⁶-C₁₆H₁₀)Cr(CO)₃ and (-⁶,⁶-C₁₆H₁₀)Cr₂(⁶-C₆H₆)(CO)₃ are studied by cyclic voltammetry. Relations between half-wave potentials of redox processes and coordination sites of fragments Cr(⁶-C₆H₆)- and Cr(CO)₃ with the ligand and their nature are found.