N. E. Kolobova

Protonation of metal carbonyl, complexes IV. An infrared study of the cyclopentadienyl complexes of vanadium, niobium and rhenium

Abstract Protonation in acidic media of compounds of the type (π-C 5 H 5 )M(CO) 4 (M = V, Nb) and (π-C 5 H 5 )Re(CO) 3 and their phosphine derivatives has been studied by IR spectroscopy. The results obtained and those from previous studies indicate that for cyclopentadienyl carbonyl complexes of Group V and VII elements with the same ligand L the basicity of the metal atom increases in the series CpMn(CO) 2 L CpV(CO) 3 L 6 H 6 Cr(CO) 2 L 2 L 3 L.

Nuclear quadrupole resonance of Mn55, Re185, Re187 in cyclopentadienylmanganese (Rhenium) tricarbonyls

1. The nuclear quadrupole resonance spectra of Mn55, Re185, Re187, and Cl35 of a number of substituted tricarbonylmanganese (rhenium) cyclopentadienyls were investigated. 2. In the system of tricarbonylmanganesecyclopentadienyls, for the group of substituents considered, the influence transmitted from the substituent in the ring to the metal according to a conjugation mechanism to a greater degree than according to an induction mechanism. 3. Additional coordination interactions arise between the substituents in the ring of the COR type (R=CH3, C6H5, CF3) and the metal; moreover, the coordination ability of the rhenium atom is higher than that of the manganese atom.

Investigation of the nuclear quadrupole resonance spectra of5Mn,185Re,187Re, and127I of derivatives of manganese and rhenium cyclopentadienyltricarbonyls

1. The NQR185Re,187Re,55Mn, and127I spectra of a number of derivatives of manganese and rhenium cyclopentadienyltricarbonyls were investigated. 2. The change in the quadrupole coupling constant on the metal atom is due to a greater degree to conjugation characteristics of the substituents than to induction characteristics; moreover, in rhenium derivatives this sensitivity is approximately an order of magnitude higher than in manganese derivatives. 3. The higher NQR127I frequencies in (CO)3ReC5H4I than in (CO)3MnC6H4I permit us to consider the (CO3)ReC5H4— group as a stronger electron acceptor than (CO)3MnC5H4-.

Comparative study of low-frequency vibrational spectra of cyclopentadienylmanganese tricarbonyl and cyclopentadienylrhenium tricarbonyl derivatives

1. A study was made of the dependence of the frequencies of the completely symmetric metal-ring and metal-carbonyl stretching vibrations in cyclopentadienylmanganese tricarbonyl and cyclopentadienyl-rhenium tricarbonyl derivatives on the character of the substituent in the cyclopentadienyl ring. 2. The different type of frequency shifts for the manganese and rhenium derivatives is explained by the substantially greater role of dative interaction in the formation of the metal-ring bond for the cyclopentadienylmanganese tricarbonyl derivatives.

Comparative study of NMR spectea of monosubstituted (C5H4X)M(CO)3 (M=Mn, Re)

The electron density on theπ-cyclopentadienyl ligand in cyclopentadienylmanganese tricarbonyl derivatives is higher than in the corresponding cyclopentadienylrhenium tricarbonyl derivatives.

Synthesis and study of some properties of triphenylsilicon, triphenylgermanium, triphenyltin and triphenyllead derivatives of manganese and rhenium π-cyclopentadienyltricarbonyls

1. The triphenylsilicon, triphenylgermanium, triphenyltin and triphenyllead derivatives of π-cyclopentadienyltricarbonylmanganese and π-cyclopentadienyltricarbonylrhenium were synthesized. The heterolysis of the CCp-E bond in these compounds was studied. 2. A compound was obtained that contained two different types of manganese carbonyl groupings in the molecule: (CO)3MnC5H4Sn(C6H5) [Mn(CO)5]2.

Action of bromine on cyclopentadienylrheniumtricarbonyl

1. The interaction of cyclopentadienylrheniumtricarbonyl and bromine in carbon tetrachloride and under reaction conditions for electrophilic substitution was investigated. 2. Cyclopentadienylrheniumdicarbonyldibromide was obtained.

Specteoscopic investigation of the comparative properties of cyclopentadienyltricarbonyls of manganese and rhenium

1. The frequencies and force constants of the CO bonds in derivatives of cyclopentadienyltricarbonylrhenium of the type of RC5H4Re(CO)3, where R=NH2, H, HgCl, Br, Cl, I, COCH3, COC6H5, COOH, CN, COC1, SO2C1, COOCH3, C5H4Re(CO)3, are linearly correlated with the parameter of the substituentσp0, which indicates an inductive nature of the transmission of the influence from the substituent R to the carbonyl ligands through the metal atom. The slope of the correlation straight line is evidence that in the case of derivatives C5H4Re(CO)3, the transmission is less effective than for derivatives C5H4Mn(CO)3. 2. For three pairs of compounds RC5H4M(CO)3 (M=Mn, Re; R=H, Br, COCH3) we studied the influence of solvents on the frequencies of the stretching vibrations of CO and measured the summary integral intensities of the bands of the valence vibrations of CO. The data are discussed from the standpoint of the nature of the dative interaction of the metal atom with the carbonyl ligand.

Borono and halo derivatives of tricarbonylcyclopentadienylmanganese and -rhenium

1. By the action of tributyl borate on tricarbonyl(lithiocyclopentadienyl)manganese and -rhenium the corresponding boronic acids were prepared. 2. Some properties of these acids were studied. In an aqueous medium they are readily hydrolyzed with formation, respectively, of tricarbonylcyclopentadienylmanganese (TCM) and tricarbonyicyclopentadienylrhenium (TCR), and under given conditions the rate of hydrolysis of TCR-boronic acid is higher than the rate of hydrolysis of TCM-boronic acid. 3. The chloro and bromo derivatives of TCR and the already-known similar derivatives of TCM were prepared by the action of cupric halides on symmetrical mercury derivatives of TCM and TCR. 4. Bromo derivatives of TCM and TCR are inert in nucleophilic exchange reactions of halogen.

Tricarbonyl(iodocyclopentadienyl)rhenium and ([bicyclopentadienyl]diyl)bis[tricarbonylrhenium]

1. By the action of mercuric chloride on tricarbonyl(lithiocyclopentadienyl)rhenium in tetrahydrofuran (CO)3ReC5H4HgCl and [(CO)3ReC5H4]2Hg were synthesized. 2. Previously unknown (CO)3ReC5H4I and [(CO)3ReC5H4]2 were prepared.