P. V. Petrovskii

Synthesis of the first 30-electron triple-decker complexes of the iron group metals with cyclopentadienyl ligands. X-Ray structure of [(η-C5H5)Ru(μ,η-C5Me5) Ru(η-C5Me5)]PF6

The first 30-electron triple-decker complexes of the iron group metals [(η-C5R5)M(μ,η-C5Me5)M′(η-C5Me5)]PF6 were synthesized by reaction of [Fe(η-C5H5)(η-C6H6)]PF6 or [Ru(η-C5R5)(MeCN)3]PF6 (R = H, Me) with decamethylmetallocenes M′(η-C5Me5)2 (M′= Fe, Ru, Os). The pentamethylcyclopentadienyl ligand η-bonded to both metal atoms is the middle deck in these sandwich compounds. Their structure was confirmed by 1H and 13C{1H} NMR spectroscopy as well as by an X-ray diffraction study of [(η-C5H5)Ru(μ,η-C5Me5)Ru(η- C5Me5)]PF6.

Electronic effects in the cyclopentadienyl ring. The 13C NMR spectraof monosubstituted ferrocenes

The chemical shifts of C(2,5) and C(3,4) carbons in the 13C NMR spectra of monosubstituted ferrocenes have been assigned using deuterium labelling. An analogy is observed between the shielding of C(2,5) and C(3,4) carbons of ferrocene derivatives and ortho- and para-carbons of benzene derivatives withthe same substituents. Electron-density distribution in the cyclopentadienyl ring is discussed on the basis of 13C NMR data.

New approaches to the synthesis of unsymmetrical diaryl selenides

Abstract Unsymmetrical diaryl selenides PhSeAr were obtained by the palladium catalysed reactions of aryl (heteroaryl) iodide or triflate with Bu 3 SnSePh in high yields. The same compounds can be obtained by the non-catalytic reactions of Bu 3 SnSePh with ArN 2 BF 4 or (ArN 2 ) 2 ZnCl 4 .

Protonation of metal carbonyl complexes: II. A PMR spectroscopic study of protonation in arenechromium tricarbonyls and arenechromium dicarbonyl triphenylphosphines

From PMR spectroscopic studies, it has been shown that C6H6Cr(CO)3, CH3C6H5Cr(CO)3, CH3OC6H5Cr(CO)3 and 1,3,5-(CH3)3C6H3Cr(CO)3 protonate at the chromium atom in a mixture of BF3·H2O and CF3COOH(11), H0≈−7 as a solvent, while CH3C6H5Cr(CO)2P(C6H5)3, CH3OC6H5Cr(CO)2P(C65)3 and 1,3,5-(CH3)3C6H3Cr(CO)2P(C6H5)3 protonate at the metal in CF3COOH(H0≈−3) as a solvent. The effect of substituents in the π-bonded benzene ring of ArCr(CO)3 and ArCr(CO)2P(C6H5)3 upon the ability of the complexes to protonate at the metal atom has been investigated, and it has been shown that electron-releasing groups enhance while electron-attracting groups hinder the protonation of these complexes. Substitution of the carbonyl ligand in ArCr(CO)3 by a triphenylphosphine group results in an increase in the basicity of the complex and facilitates its protonation in acidic media.

σ,π-Binuclear complexes of transition metals coordinated to the monoolefin

Abstract σ-Vinyl derivatives of iron, tungsten, or rhenium react with iron nonacarbonyl to produce σ,π-binuclear complexes of the metals in which the presence of metal-metal bonds is very dependent on the nature of the metal. That the formation of the complexes containing a metal-metal bond does not necessarily involve the presence of an electron-withdrawing group attached to the vinyl ligand has been demonstrated for the σ-vinyl derivatives of iron, although it has been shown that for such bonding to be observed the double bond in the σ-derivative should be adjacent to the iron.

57Fe NMR chemical shifts and 57Fe, 13C coupling constants in α-ferrocenyl carbocations. Direct metal participation in the stabilization of metallocenyl carbocations

Abstract The 13 C{ 57 Fe} double resonance method has been used to investigate 57 Fe-enriched samples of ferrocene derivatives, α-ferrocenyl carbocations and carbonyl complexes with various σ- and π-hydrocarbon ligands. In the α-ferrocenyl carbocations the 57 Fe resonances span a 1200 ppm range, being a sensitive tool of direct iron participation in the stabilization. The 57 Fe resonances in the carbocations [FcCH 2 ][HSO 4 ] (I), [FcCHMe][HSO 4 ] (II), [FcCHPh][HSO 4 ] (III), [FcCHC 5 H 4 Mn(CO) 3 ][CF 3 CO 2 ] (IV), [(Fc) 2 CH][BF 4 ] (V), [FcCHC 5 H 4 RuC 5 Hs][BF 4 ] (VI) and [FcCMe 2 ][HSO 4 ] (VII), −523.6, −219.3, 221.0, 368.7, 699.0, 405.0 and 288.5 ppm, respectively, relative to ferrocene, are interpreted in terms of rehybridization of the iron non-bonding d orbitals (shielding effect and the electron withdrawing effect of the substituent in the cyclic ligand (deshielding effect). The role of rehybridization of non-bonding iron orbitals in the low-frequency shift of the 57 Fe resonances, in addition to that in the previously investigated complex [(C 5 H 5 ) 2 FeH][BF 3 OH] (−1109.3 ppm), has been demonstrated for bridge-substituted [3]ferrocenophanes, whose ring tilting induces a low-frequency shift of up to 340 ppm relative to their unbridged analogues. The 13 C NMR spectra of carbocations V and VI reveal a temperature dependence due to the rotation around the C(1)C α exocyclic bonds. In carbocation VI the ruthenium atom effectively competes with the iron atom to bond with C α whereas in carbocation V two equivalent metal atoms possess the same ability for such bonding; as a result, complex V has a more pronounced “carbenium ion” nature than IV and VI, as indicated by the relative positions of the 13 C α resonances in carbocations IV, V and VI: δ 122.4, 147.2 and 116.9 ppm, respectively. The values of 57 Fe, 13 C coupling constants for α-ferrocenyl carbocations exclude Fe-C α σ-bonding and support a structure in which the iron atom is π-bonded with six carbon atoms of a fulvenoid ligand. According to the data on 57 Fe resonances and 57 Fe, 13 C coupling constants in α-ferrocenyl carbocations the strength of FeC α bonding is markedly influenced by the electronic effect of the substituent at C α , being even lower in carbocation I than that of Fe-cyclopentadienyl carbon atoms.

Crown compounds for anions. Unusual complex of trimetric perfluoro-o-phenylenemercury with the bromide anion having a polydecker sandwich structure

Abstract Here we show that cyclic trimetric perfluoro- o -phenylenemercury ( o -C 6 F 4 Hg) 3 is capable of forming complexes with [PPh 4 ] + Br − , [PPh 3 Me] + I − and [PPh 4 ] + Cl − of the composition [( o -C 6 F 4 Hg) 3 X] − [PR 3 R′] + (X = Br, R = R′ = Ph; X = I, R = Ph, R′ = Me) or {[( o -C 6 F 4 Hg) 3 X 2 } 2− [PR 3 R′] + 2 (X = Cl, R = R′ = Ph). An X-ray study of the complex with [PPh 4 ] + Br − revealed that it has the unusual structure of the polydecker bent sandwich wherein each Br − anion is coordinated with six mercury atoms of two neighbouring molecules of ( o -C 6 F 4 Hg) 3 .

Dicationic triple-decker complexes with a bridging boratabenzene ligand

Abstract New dicationic triple-decker complexes with a bridging boratabenzene ligand [Cp*Fe(μ-η:η-C 5 H 5 BMe)ML]X 2 (ML=CoCp*, 6 (CF 3 SO 3 ) 2 ; RhCp, 7 (BF 4 ) 2 ; IrCp, 8 (CF 3 SO 3 ) 2 ; Ru(η-C 6 H 6 ), 9 (CF 3 SO 3 ) 2 ; Ru(η-C 6 H 3 Me 3 -1,3,5), 10 (CF 3 SO 3 ) 2 ; Ru(η-C 6 Me 6 ), 11 (CF 3 SO 3 ) 2 ) were synthesized by stacking reactions of Cp*Fe(η-C 5 H 5 BMe) ( 2 ) with the corresponding half-sandwich fragments [ML] 2+ . The structure of 10 (CF 3 SO 3 ) 2 was determined by X-ray diffraction study.

Synthesis and structure of rhodium complexes with monoanionic carborane ligand [9-SMe2-7,8-C2B9H10]−

Abstract (Rhodacarborane)halide complexes [(η-9-SMe 2 -7,8-C 2 B 9 H 10 )RhX 2 ] 2 ( 4a : X=Cl; 4b : X=Br; 4c : X=I), which are analogous to [Cp*RhX 2 ] 2 , were synthesized by reaction of (η-9-SMe 2 -7,8-C 2 B 9 H 10 )Rh(cod) (cod=1,5-cyclooctadiene) with HX. Compounds 4 were used to prepare several sandwich and half-sandwich complexes containing (η-9-SMe 2 -7,8-C 2 B 9 H 10 )Rh fragment. 2e-Ligands destroy the dimeric structure of 4 to give the adducts (η-9-SMe 2 -7,8-C 2 B 9 H 10 )RhLX 2 , exemplified by preparation of (η-9-SMe 2 -7,8-C 2 B 9 H 10 )Rh(CO)I 2 and (η-9-SMe 2 -7,8-C 2 B 9 H 10 )Rh(PPh 3 )Cl 2 . The reaction of 4a with dppe in the presence of TlBF 4 affords the cationic complex [(η-9-SMe 2 -7,8-C 2 B 9 H 10 )Rh(dppe)Cl]BF 4 ( 7 BF 4 ). Sandwich complexes [(η-9-SMe 2 -7,8-C 2 B 9 H 10 )Rh(η-C 5 R 5 )]CF 3 SO 3 ( 11a CF 3 SO 3 : R=H; 11b CF 3 SO 3 : R=Me) were obtained by abstracting chloride from 4a by CF 3 SO 3 Ag with subsequent treatment with C 5 R 5 H. Complex 11b PF 6 was prepared by reaction of [Cp*RhCl 2 ] 2 with Na[9-SMe 2 -7,8-C 2 B 9 H 10 ]. Complex (η-9-SMe 2 -7,8-C 2 B 9 H 10 )Rh(η-7,8-C 2 B 9 H 11 ), containing two carborane ligands, was obtained by reaction of 4a with Tl[Tl(η-7,8-C 2 B 9 H 11 )]. Structures of 7 BF 4 and 11b PF 6 were confirmed by X-ray diffraction study.

Iron- and Ruthenium-Containing Triple-Decker Complexes with a Central Pentaphospholyl Ligand − X-ray Structures of [(η-C5H5)Fe(μ-η:η-P5)Ru(η-C5Me5)]PF6 and [(η-C5Me5)Ru(μ-η:η-P5)Ru(η-C5Me5)]PF6

Triple-decker cationic complexes with a central pentaphospholyl (pentaphosphacyclopentadienyl) ligand [Cp*M(μ-η:η-P5)M′(η-C5R5)]+ (3b: M = M′ = Fe, R = Me; 4a: M = Ru, M′ = Fe, R = H; 4b: M = Fe, M′ = Ru, R = H; 4c: M = Fe, M′ = Ru, R = Me; 5a: M = M′ = Ru, R = H; 5b: M = M′ = Ru, R = Me) were synthesized by exploitation of the stacking reactions of pentaphosphametallocenes Cp*M(η-P5) (1: M = Fe; 2: M = Ru) with half-sandwich fragments [(η-C5R5)M′]+. They were isolated as salts with BF4− or PF6− anions, and the structures of 4aPF6 and 5bPF6 were determined by X-ray diffraction. Triple-decker complexes with a central pentaphospholyl ligand are less reactive in nucleophilic degradation reactions than analogous complexes with C4Me4P and Cp* ligands in the bridging position. Only 4a and the previously known analogue 3a (M = M′ = Fe, R = H), containing the CpFe fragment, are nucleophilically destroyed by MeCN and NaI. The electrochemical properties of 2, 3a, 3b, 4a−c, 5a and 5b and the related cobalt-containing complexes [(η-C4Me4)Co(μ-η:η-P5)MCp*]+ (6: M = Fe; 7: M = Ru) were investigated. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)