Nikolai A. Ustynyuk

Indenyl-and flourenyl-transition metal complexesss : I. Synthesis, structures, and reactions of ν5-and ν6-derivatives of chromium group metals

Abstract The reaction leading to the ν5-fluorenyl-and ν-indenyl-tricarbonylmetallate anions, ν5-C13H9(CO)3Cr- and ν5-C9H7(CO)3M- where M stands for Cr, Mo, W have been studied. Deprotonation of (ν6-fluorene)Cr(CO)3 with t-BuOK seemingly proceeds via the corresponding ν6-anionic intermediate which is transformed into the ν5-isomer with a conversion halftime of several minutes. Chromium and molydenum ν5-anions rearrage on treatment with CH3COOH to the corresponding ν6-indene and fluorene complexes. Protonation of ν5-C9H7- (CO)3W- leads to the stable hyride ν5-C9H7(CO)3WH. All the anions studied react with Hg(CN)2 to give symmetric organomercury derivatives containing M–Hg bonds (M=Cr, Mo, W). The reaction of ν5-C9H7(CO)3Cr- and ν5-C13H9 structure and containing a Cr–CH3 bond: the product ν5-C9H7(CO)3CrCH3 has undergo thermal rearrangement to the ν6-compounds via transfer of the CH3 group to the five-membered ring and of the Cr(CO)3 group to the benzene nucleus. The molybdenum and tungsten anions form stable σ-methyl derivatives in reactions with CH3I. The possible reversible isomerization processes involving anionic and neutral compounds are considered form mechanic and stereo-chemical points view.

The crystal and molecular structure of oxo-π-cyclopentadienylπ-diphenylacetylene-σ-phenyltungsten

Abstract X-Ray studies indicate that the photochemical reaction of C5H5W(CO)3C6H5 with tolane results in the formation of oxo-π-cyclopentadienyl-π-diphenylacetylene-σ-phenyltungsten. The observed shortening of WC(acetylene), WC(σ-phenyl) and WO bond lengths seems to be caused by an increased back donation due to the electron deficiency of the complex investigated.

Electrochemical generation of 19- and 20-electron rhodocenium complexes and their properties

Abstract The electrochemical reduction of the rhodocenium salts [Rh(η 5 -C 5 Me 5 )(η 5 -L)] + PF 6 − ( 2 + , L  C 5 H 5 ; 3 + L  C 5 Me 5 ; 4 + L  C 9 H 7 ) has been studied by cyclic voltammetry. All three complexes ( 2 + - 4 + ) are reduced in two one-electron processes, first to the 19-electron radicals ( 2 - 4 ) and then to the 20-electron anions ( 2 − - 4 − ). When complex 2 + was reduced in bulk (NaHg in THF) the dinuclear complex, [(η 5 -C 5 H 5 )Rh(μ-η 4 : η 4 -C 5 Me 5 -C 5 H 5 )Rh(η 5 -C 5 Me 5 )] ( 6a ), obtained by dimerization of 2 , was isolated as sole product. Analogous reduction of 3 + gave the η 4 -pentamethylcyclopentadiene complex, [Rh(η 5 -C 5 Me 5 )(η 4 -C 5 Me 5 H)] ( 7 ). Reduction of 4 + leads to formation of a stable radical 4 .

Regioselective synthesis of π-complexes of substituted polycyclic aromatic compounds. Experimental (NMR) and theoretical (DFT) studies of η6,η6-haptotropic rearrangements in naphthalenechromiumtricarbonyl complexes☆

A new regioselective method for the synthesis of (η6-naphthalene)chromium tricarbonyl complexes bearing a substituent R in desired positions of either the coordinated or non-coordinated ring was proposed. The kinetics of η6,η6-haptotropic rearrangements (IRHR) was investigated by NMR spectroscopy for ten pairs of isomer complexes (R=D, CH3, Me3Sn, Me3Si and Cl in position 1 or 2 of coordinated or non-coordinated rings). The free activation energies ΔG# fall into a quite narrow range of 28–31 kcal mol−1 and are therefore relatively insensitive to the influence of substituent R whereas equilibrium constants of IRHR change considerably from 0.03 to 17.26 within the compounds investigated. Electron donating (withdrawing) substituents R increase (decrease) the relative thermodynamic stability of the isomers containing a substituent in coordinated rings. The density functional theory method (DFT) with extensive basis set describes quite satisfactory the geometry and the energy of ground states and correctly predict that the least motion route of Cr(CO)3 from one ring to another via the center of the C4a–C8a bond is forbidden. The transition state for the rearrangement of (η6-naphthalene)chromium tricarbonyl has trimethylenemethane structure of C2v-symmetry in which the Cr(CO)3-group is slightly shifted to the ligand periphery. For the monosubstituted naphthalenechromium tricarbonyls thus, there are two reaction channels of the chromium tricarbonyl group slippage between unsubstituted and substituted rings, one of which is practically unperturbed determining the low sensitivity of the rearrangement rate to the effects of ligand substitution even for 1-R substituted complexes. Calculated activation barriers are in a good accordance with the experimentally determined ΔG# values.

Thermal decomposition of (η)-cyclopentadienyl)- tricarbonyl(σ-phenylethynyl)molybdenum and the molecular structure of a molybdenum binuclear complex with a bridging 1,4-diphenylbutadiyne ligand [η- C5H5)(CO)2Mo]2(μ-1,2-η-C6H5CCCCC6H5)

Abstract Thermolysis of C5H5(CO)3MoCCC6H5 (I) in octane at 110–115°C results in the formation of [(η-C5H5)(CO)2Mo]2(μ-1,2-η-C6H5CCCCC6H5) (II). The structure of II was determined by X-ray analysis. The reaction scheme is discussed.

Indenyl and flourenyl transition metal complexes : III. Some new reactions of flourenyl- and indenyl-metal tricarbonyl anions

Abstract Deprotonation of η 6 -flourenechromium tricarbonyl (III) with excess t-BuOK in THF at70°C yields [η 6 -C 13 H 9 Cr(CO) 3 ] − K + (Ia), which isomerizes to η 5 -C 13 H 9 Cr(CO) 3 Cr − K + (II) at temperatures above −20°C. [η 6 -C 13 H 9 Cr(CO) 3 ] − Li + (Ib) may be obtained in the solid state by treatment of III with BuLi in absolute ether followed by precipitation with n-hexane. Methylation of Ib and II with methyl iodide goes stereospecifically to give η 6 - exo - (IX) and η 6 -(9- endo -methylfuorene)chromium tricarbonyl (XII) from Ib and II, respectively. Acylation of Ia with CH 3 COCl yields the acetate of 9-acetylfluorenechromium tricarbonyl (VII) in its enol form. Treatment of III with excess t-BuOK and CH 3 I in THF at −30°C leads to the derivative (XI), which is fully methylated at C(9). Phenyldiazonium borofluoride, diphenyliodonium iodide, ferrocenium borofluoride, trimethylchlorostannane and triethylbromogermane react with η 5 -C 9 H 7 (CO) 3 M − K + in THF to give compounds of the η 5 -series: η 5 -C 9 H 7 (CO) 2 MN 2 C 6 H 5 (M  Cr, Mo, W), η 5 -C 9 H 7 (CO) 3 WC 6 H 5 , [η 5 -C 9 H 7 (CO) 3 M] 2 (M  Mo, W), η 5 -C 9 H 7 (CO) 3 MSnMe 3 (M  Cr, Mo, W) and η 5 -C 9 H 7 (CO) 3 MGeEt 3 (M  Cr, Mo, W), respectively.

Synthesis and structure of a series of new haloaryl imido complexes of molybdenum

Abstract The synthesis of a series of mono- and bis-haloarylimido molybdenum(VI) complexes is described. Two methods of introducing the electron poor imido functionality are employed, first the condensation of substituted anilines with Na2MoO4 in the presence of Me3SiCl/NEt3, secondly the sulfinyl amine metathesis with [Mo(O)2Cl2(dme)] (1). The latter method works even in cases, when the first one does not work. Crystal structures of three complexes [Mo(NC6F5)(O)Cl2(dme)] (2a), [Mo(N-2,6-Cl2C6H3)2Cl2(dme)] (3b) and [Mo(N-2,4,6-Br3C6H2)2Cl2(dme)] (4) are reported. The unusually small MoNC(Ar) angle of 149.1(5)° has been found in the structure of 4.

Reduction of ruthenium arenecyclopentadienyl complexes reactions induced by electron transfer

Abstract Ruthenium arenecyclopentadienyl complexes [Ru(η5-C5R5)(η6-arene)]+ (1, R = H, arene = C6H6; 2, R = Me, arene = C6H6; 3, R = H; arene = C6H3Me3; 4, R = Me, arene = C6H3Me3; 5, R = H, arene = C6Me6; 6, R = Me, arene = C6Me6; 7, R = Me, arene = C10H8) and [Ru(η5-C9H7)(η6-C6H6)]+ (8) have been studied by cyclic voltammetry; the complexes are capable of both reduction and oxidation. The reduction peak potential values for 1–6 become more negative by about 31 mV for each Me-group at the arene ring and 61 mV for each Me-group at the cyclopentadienyl ring. Reduction of naphthalene complex 7 proceeds by two one-electron processes; the first one is reversible and the second one is irreversible. Two reversible reduction peaks were observed for indenyl complex 8. The following reactions occur on reduction of benzene complexes 1, 2 and 8 with sodium amalgam in tetrahydrofuran (THF): hydrogen atom addition to and decoordination of benzene ligand as well as dimerization of ligand-to-ligand type. Mesitylene compounds 3 and 4 form dimers [(η5-C5R5)Ru(μ-η5:η5-Me3H3C6C6H3Me3)Ru(η5-C5R5)] (14, R = H; 15, R = Me) in both chemical and electrochemical reduction processes. Reaction of [Ru(η5-C5H5)(η6-C6Me6)]+ (5) with sodium amalgam in THF leads to the dimer [(η5-C5H5)Ru(μ-η5:η5-Me6C6C6Me6)Ru(η5-C5H5)] (16) as the major product; products of H-atom addition to both hexamethylbenzene and cyclopentadienyl ligands, [Ru(η5-C5H5)(η5-C6Me6H)] (17) and [Ru(η4-C5H6)(η6-C6Me6)] (18), are also formed in low yields. In the case of permethylated 6 only H-atom addition to hexamethylbenzene was observed and the mixture of endo-H and exo-H isomers [Ru(η5-C5H5)(η5-C6Me6H)] (19a,b) was isolated. Reduction of 7 gives [Ru(η5-C5Me5)(η5-C10H9)] (20). The modes of reaction of 19-electron radicals formed by reduction of 1–8 depend on electronic and steric properties of ligands.

Inter-ring η6⇄η6 haptotropic rearrangements in naphthalenetricarbonylchromium complexes

Abstract Two methods for the controlled introduction of substituents in the coordinated and non-coordinated ring of η 6 -naphthalenetricarbonylchromium are proposed. When the selectively substituted naphthalenetricarbonylchromium complexes are heated the tricarbonylchromium groups are redistributed between the substituted and the unsubstituted rings because of inter-ring haptotropic rearrangements. The rate constants of these isomerizations were measured. During rearrangement of individual isomers of (1-methylacenaphthene)tricarbonylchromium the configuration of the methyl group does not change, thus testifying to intramolecular rearrangements.

Synthesis and molecular structure of the binuclear complex of chromium with a bridging bis-carbyne ligand

Abstract The binuclear bis-carbyne-chromium complex (η-C 5 H 5 )(CO) 2 CrCC(Ph)C(Ph)CCr(CO) 2 (η-C 5 H 5 ) has been obtained from (η-C 5 H 5 )(CO) 3 CrCCC 6 H 5 via a multi-stage redox cycle. The structure of this complex has been determined by an X-ray study.