G. A. Domrachev

Some peculiarities of structure, stability and reactivity of compounds containing metal—metal bonds

Abstract The complete X-ray analysis of bis(triphenylgermyl)mercury has been carried out. HgGe bond lengths in the well-known structures of bi- and polynuclear organometallic compounds are shown to be covalent and change over a wide range. The influence of screening efficiency of central metal atom in bi- and polyorganometallic compounds upon their reactivity and thermal stability has been treated.

Rydberg series in the near-uv vapour-phase absorption spectra of (η6-arene)2Cr(0) and (η6-arene)2 V(0) complexes

Abstract The vapour-phase electronic absorption spectra of (η 6 -arene) 2 M(0) (arene=benzene (I), toluene (II), ethylbenzene (III), isopropylbenzene (IV), tert-butylbenzene (V), 1,2-dimethylbenzene (VI), 1,3-dimethylbenzene (VII), 1,3,5-trimethylbenzene (VIII); M=Cr, V) have been investigated in the 12500–45000 cm −1 region. In all spectra Rydberg series converging to the ionization limits have been found. The most sharp Rydberg bands are assigned to the 3 d ( a 1g ) → Rnp series. The ionization limits for the I Cr -VIII Cr chromium (0) complexes are 5.45±0.01, 5.29±0.01, 5.25±0.01, 5.21±0.01, 5.18±0.01, 5.15±0.01, 5.14±0.01, 5.01±0.02 eV, respectively, and those for the vanadium(0) I V -VIII V complexes are 6.16±0.02, 5.98±0.02, 5.94±0.02, 5.90±0.02, 5.86±0.02, 5.82±0.03, 5.80±0.03, 5.63±0.03 eV, respectively. These limits correspond to the ionization from the highest occupied orbital 3d(a 1g ) and are in a good agreement with the photoelectron spectroscopy data which are known for some complexes. Rydberg bands in the spectra of (η 6 -arene) 2 Cr(0) and (η 6 -arene) 2 V(0) are characterized by similar values of the quantum defects.

The interaction of nickelocene with bis(triphenylgermyl)cadmium

Abstract The reaction of bis(triphenylgermyl)cadmium with nickelocene proceeds through the displacement of a cyclopentadienyl ring and the formation of an organopolymetallic compound containing nine metal atoms: This is a new type of organometallic compound, containing NiCd bonds.

Rydberg transitions in the near-ultraviolet vapor-phase absorption spectra of 3d metallocenes

Abstract The electronic absorption spectra of Cp 2 M (M = V, Cr, Mn, Fe, Co, Ni; Cp = η 5 -C 5 H 5 ), Cp′ 2 Fe (Cp′ = η 5 -C 5 H 4 Me) and Cp * 2 Mn (Cp * = η 5 -C 5 Me 5 ) in the vapor phase have been investigated. Vapor-phase spectra differ from the solution ones. In the most cases, this is caused by the presence of Rydberg bands in the vapor-phase absorption spectra. These bands disappear on going to the spectra of solutions. The 3d(a 1g ) → R n p Rydberg transitions are revealed most clearly. The bands at 40 700, 41 000, 41 240, 41 570 cm −1 in the spectrum of Cp 2 Fe and the band at 39 650 cm −1 in the spectrum of Cp′ 2 Fe are unambiguously assigned to the 3d(a 1g ) → R4p transition which displays a vibrational structure for ferrocene (0,0 transition at 41 000 cm −1 ). In addition, the vapor-phase spectrum of ferrocene shows bands at 42 490 and 42 800 cm −1 which can be assigned to the second component of the 3d(a 1g ) → R4p transition. The peaks at 39 400 and 46 470 cm −1 in the spectrum of vaporous vanadocene correspond to the two first members of the Rydberg series: 3d(a 1g ) → R4p and 3d(a 1g ) → R5p. Analogous assignment for the bands at 35 000 and 45 000 cm −1 in the vapor-phase spectrum of nickelocene seems to be reasonable. For Cp * 2 Mn, the 3d(a 1g ) → R n p ( n = 4, 5, 6) Rydberg series is observed. The energy of ionization from the 3d(a 1g ) orbital of Cp * 2 Mn (5.4 eV) has been determined as a convergence limit of the series. The shoulder at 48 450 cm −1 in the spectrum of vaporous chromocene may be interpreted as one of the first members of the Rydberg n p series. The intensity of the band at 47 000 cm −1 in the spectrum of cobaltocene changes when going from the vapor phase to solution. This can be explained by the contribution of the 3d(a 1g ) → R4p Rydberg transition.

Ultraviolet vapour-phase absorption spectra of d6 metallocenes

Abstract The electronic absorption spectra of vaporous Cp*2M (Cp = η5-C5H5, Cp*= η5-C5Me5; M = Fe, Ru, Os) and CpRuCp* have been investigated and compared with those of complexes in pentane solution. Vapour-phase spectra differ strongly from those measured in solution. This is due to the presence of Rydberg excitations in the spectra of vaporous metallocenes. The CP2M spectra show two sharp absorption bands which disappear on going from the vapour phase to the solution phase. They have been unambiguously assigned to the symmetry allowed nd(a1g → R(n + 1)p(e1u) and nd(a1g) → R(n + 1)p(a2u Rydberg transitions (n = 3, 4, 5 for M = Fe, Ru, Os, respectively). One peak in the vapour-phase spectra of Cp*2M corresponds to these promotions. Two Rydberg bands have been found in the spectrum of vaporous CpRuCp*. The excitations from the 4d(a1) nonboding orbital to the R5s and R5p Rydberg orbitals are responsible for these bands. The electronic absorption spectra of d6 metallocenes in the vapour phase, in contrast to those in solution, appear to be sensitive to the changes in molecular symmetry.

The electronic absorption spectra of the alkyl-substituted derivatives of bis(benzene)chromium(0) in the vapour phase

Abstract The UV and visible absorption spectra of (arene) 2 chromium(0) (arene = benzene (I), toluene (II), ethylbenzene (III), cumene (IV), tert-butylbenzene (V), mesitylene (VI) in the vapour phase have been investigated. Four band systems A,B,C and D are revealed in the spectra. The bands of the system with the shortest wavelengths, D, represent the Rydberg series. The first ionisation potentials IP a 1 g , 5.18 and 5.01 eV respectively. The Rydberg bands correspond to the allowed electrodipole transitions from the highest occupied molecular orbital (MO) a 1 g to the vacant MO of either the a 2 u or e 1 u type. System C corresponds to the intense band of the solution spectra. The electronic transition e 2 g → e ★ 2 g obviously makes a great contribution to this system. System B is assigned to the transition from a 1 g to vacant a 2 u or e 1 u MO, which can be Rydberg orbitals. System A can be assigned to the a 1 g → e ★ 2 u transition or to the Rydberg transition, which is forbidden in the D 6 h point group but becomes allowed upon reduction of symmetry.

Synthesis and structures of the six-coordinate donor-acceptor complexes R3(C6H4O2)Sb…L (R=Ph, L=OSMe2 or ONC5H5; R=Me, L=ONC5H5 or NC5H5) and R3(C2H4O2)Sb…L (R=Ph, L=ONC5H5; R=Cl or C6F5, L=OPPh3)

One-pot oxidation of R3Sb (R=Ph, Me, Cl, or C6F5) withtert-butyl hydroperoxide in the presence of 1,2-diols and monodentate donor compounds was studied. The structures of the resulting neutral organic donor-acceptor SbV complexes, Ph3(C6H4O2)Sb…OSMe2, Ph3(C6H4O2)Sb…ONC5H5, Me3(C6H4O2)Sb…ONC5H5, Me3(C6H4O2)Sb…NC5H5, Ph3(C2H4O2)Sb…ONC5H5, and Cl(C6F5)2(C2H4O2)Sb…OPPh3, were established by X-ray diffraction analysis. In these complexes, the coordination environment about the Sb atoms is a distorted octahedron. The Sb−O(N) distances and the Sb−O−E angles (E=S, N, or P) vary over wide ranges.

Electronic absorption spectra of molybdenum(0) bisarene complexes, (η6-Arene)2Mo0

Abstract The UV and visible absorption spectra of (η 6 -Arene) 2 Mo 0 (Arene = benzene (I), toluene (II), m -xylene (III), mesitylene (IV)) in the vapor phase and in the pentane solution have been investigated. Rydberg series converging to the ionization limit have been found in the spectra of vaporous complexes. The sharpest Rydberg bands correspond to the transitions 4 d ( a 1 g ) → Rnp ( e 1 u ) and 4 d ( a 1 g ) → Rnp ( a 2 u ). The band arising from the 4 d ( a 1 g ) → R 5 s ( a 1 g ) Rydberg transition has been found in the vapor-phase spectra of the II and III complexes. Some weak bands in the vapor-phase spectra have been tentatively assigned to the 4 d ( a 1 g ) → Rnd transitions. Rydberg bands disappeared from the spectra on going from vapor phase to pentane solution. The ionization limits for I–IV are 5.525 ± 0.010, 5.375 ± 0.010, 5.250 ± 0.010, 5.137 ± 0.010 eV, respectively. These limits correspond to the ionization from the highest occupied molecular orbital 4 d ( a 1 g ) and are consistent with the first ionization potentials determined by photoelectron spectroscopy for the complexes I, II, and IV.

Structures of Rydberg transitions in the absorption spectra of methyl-substituted derivatives of bis(η6-benzene)chromium

The effect of methylation of ligands in bis(η6-benzene)chromium (1) on the structure of Rydberg transitions in absorption spectra has been studied. A detailed analysis and interpretation of all Rydberg elements of the vapor-phase spectra of bis(η6-benzene)chromium (2), bis(η6-o-xylene)chromium (3), bis(η6-m-xylene)chromium (4), and bis(η6-mesitylene)chromium (5) was carried out. The vapor-phase electronic absorption spectrum of bis(η6-p-xylene)chromium (6) was measured, and the assignment of the Rydberg bands was made for the first time. The first ionization potentials of complexes 2–5 were refined. The energy of detachment of the 3dz2 electron and the parameters of the Rydberg excitations for molecule 6 were determined. The vibronic components of the 3dz2→R4px,y transition in the spectra of complexes 2 and 6 were assigned. The differences in the Rydberg structure of the spectra of compounds 2–6 were analyzed in terms of the selection rules for optical transitions in the corresponding symmetry groups. The vapor-phase spectra correspond to conformers with the symmetry groupsC2v andC2 for complexes 2–4, with the symmetry groupsD3h andD3 for compound 5, and with the symmetry groupD2d for complex 6.

Stoichiometric synthesis of fullerene compounds with lithium and sodium and analysis of their IR and EPR spectra

A modified method is proposed for preparing fullerene compounds with alkali metals in a solution. The compounds synthesized have the general formula MenC60(THF)x, where Me = Li or Na; n=1–4, 6, 8, or 12; and THF = tetrahydrofuran. The use of preliminarily synthesized additives MeC10H8 makes it possible to prepare fullerene compounds with an exact stoichiometric ratio between C60n− and Me+. The IR and EPR spectra of the compounds prepared are analyzed and compared with the spectra of their analogs available in the literature. The intramolecular modes Tu(1)-Tu(4) for the C60n− anion are assigned. The splitting of the Tu(1) mode into a doublet at room temperature for MenC60(THF)x (n=1, 2, 4) compounds indicates that the fullerene anion has a distorted structure. An increase in the intensity of the Tu(2) mode, a noticeable shift of the Tu(4) mode toward the long-wavelength range, and an anomalous increase in the intensity of the latter mode for the Li3C60(THF)x complex suggest that, in the fullerene anion, the coupling of vibrational modes occurs through the charge-phonon mechanism. The measured EPR spectra of lithium-and sodium-containing fullerene compounds are characteristic of C60− anions. The g factors for these compounds are almost identical and do not depend on temperature. The g factor for the C60n− anion depends on the nature of the metal and differs from the g factor for the C60− anion.