D. N. Kravtsov

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.

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 crystal structure of bis(triphenylphosphine)gold tricyanomethanide, [(PPh3)2Au]+ [C(CN)3]−

Abstract A new unusual transformation of tetracyanoethylene (TCE) into a tri-cyanomethanide anion [C(CN)3]− has been found. This transformation occurs as a result of action of tris(triphenylphosphinegold)oxonium tetrafluoroborate [O(AuPPh3)3]+BF4− on TCE or its donor-acceptor complexes with toluene and 2.4-dihydro-1.3-diphenylcyclopenta(b)indene, to give [(PPh32Au]+[C(CN)3]− (I). The X-ray diffraction study of I (20°, λMo-Ka, 1569 reflections, space group C2/c, Z = 4, R = 0.0296) has revealed that the cations [Au(PPh3)2]+ occupy specific positions in the inversion centres and the anions [C(CN)3− are located on the ‘2’ axes. No. Au…N interaction in I has been found. Complex I has been characterized by 1H and 31P NMR and IR spectroscopy. The conductivity of I in CH3OH-CH3CN solutions has been measured.

Characteristic structural features of cyclopentadienyl derivatives of post-transition metals: III. Synthesis and structure of fluorenyl (triphenylphosphine) gold(I)☆

Abstract The fluorenyl gold derivative C 13 H 9 AuPPh 3 (I) was obtained by fluorene auration with the complex [(AuPPh 3 ) 3 O] + BF 4 − or interaction of C 13 H 9 Li or C 13 H 9 Na with ClAuPPh 3 . An X-ray structure study of I (−120°C, λ Mo, 8192 reflections, space group P 2 1 / c , Z = 12, R = 0.024) shows that the Au atom in I has η 1 coordination. Moreover, the structure of three geometrically different, crystallographically independent molecules of I in crystal indicates limited structural nonrigidity, i.e. pendular motion” of the AuPPh 3 group at the sp 3 -hydridized carbon atom of the fluorenyl ligand. The PMR spectral characteristics of I are typical of stereochemically rigid σ-organic gold(I) derivatives.

Study of redox reactions of bis(arene) chromium complexes by the rotating disk electrode technique. IV: Electrochemical oxidation and ionization potentials of bis(arene) chromium complexes

Abstract The reversible electrochemical oxidation of a series of bis(arene)chromium com-plexes has been studied by use of the rotating disk electrode technique The half-wave potentials E 1/2 show an excellent correlation with the meta -substituent constants. The E 1/2 values were found to correlate well with the vertical ionization potentials ( IP ) of the same complexes in the gas phase determined from their He(I) photoelectronic spectra.

Electronic structure of bis-arene-chromium complexes

Abstract Dibenzenechromium derivatives of the type (C 6 H 5 R 1 )Cr(C 6 R 5 R 2 ) have been studied by He-I photoelectron spectroscopy. Substituent parameters have been found which allow the first and second ionization potentials of the bis-arene-chromium complexes to be determined using a very precise additive scheme. It has been shown that the change in the energy of the highest occupied MOs of the molecules is determined by the electrostatic field of ligands. The molecular electrostatic potentials of a number of species (C 6 H 5 R 1 )(C 6 H 5 R 2 ) have been calculated and the equation relating IP to ϕ( R ) has been found. A scheme for constructing the energy level diagram for dibenzenechromium and its derivatives is suggested.

Indenyl and fluorenyl transition metal complexes: XIV. Synthesis and reactions of chromium tricarbonyl complexes of 5,10-dihydroindeno[2,1-α]indene

Abstract 1-4,4a,10b-η 6 -5,10-dihydroindeno[2,1-α]indene chromium tricarbonyl (III) has been obtained by Rauschs method. Deprotonation of III by t-BuOK in THF solution, by potassium solution in HMPTA or by KH in THF at −65°C yields an η 6 -anion IV, which is irreversibly rearranged into η 5 -anion V at 20°C. Action of n-BuLi/t-BuOK mixture in THF at −65°C results in the formation of η 6 -dianion VI, which is irreversibly converted into η 5 -dianion VII above 0°C. Alkylation of IV with benzyl iodide yields 5- exo -benzyl(III). Reaction of V with benzyl iodide leads to the σ-benzyl derivative, which is isomerized into 5- endo -benzyl(III). The reaction of V with N -nitroso- N -methyltosylamide yields the η 5 -nitrosodicarbonyl complex of chromium (XI).

X-ray structure and fluxional behaviour of N,N′-di-p-fluorophenyltriazenido complex of nickel(II)

The Ni(II) triazenide complex, trans -( o -Tol)Ni(PEt 3 ) 2 N 3 Ar 2 (Ar= p -FC 6 H 4 ) ( 1 ), was synthesized by the reaction of trans -( o -Tol)Ni(PEt 3 ) 2 Br with Ar 2 N 3 Na. The crystal structure as well as the 1 H-, 19 F- and 31 P-NMR spectra in toluene- d 8 at different temperatures are reported. It was found that the triazenido group acts as a monodentate ligand. Complex 1 in solid state has a S - cis -structure with NiN(3) σ-bond and exists as a 3:1 mixture of two isomers with cisoid or transoid orientation of the Me group of the o -tolyl ligand relative to the N(1)N(2) bond. It was established that the N , N ′-migration of ( o -Tol)Ni(PEt 3 ) 2 group occurs in a solution of 1 . The migration rate increases with the temperature increase in the range from −104 to −45°C. However, a further increase in the temperature slows down the process.

Indenyl and fluorenyl transition metal complexes: XV.Reactions of 1,1-dimethylindene, spirocyclopropane-1,1-indene, and spirocyclopropane-9,9-fluorene with L3M(CO)3 (L = NH3, Py; M = Cr, Mo, W)☆

Abstract Reaction of indene, 1,1-dimethylindene, spirocyclopropane-1,1-indene, and spirocyclopropane-9,9-fluorene with Py 3 M(CO) 3 /BF 3 · OEt 2 (M = Cr, Mo, W) involves two competing processes: (i) the formation of the 6 -arene complexes (A) and (ii) the oxidative addition at the C(1)R and C(9)R bonds (R = alkyl) with the formation of chelated σ,π-complex ( B ). The reaction pathway ( A or B ) is determined both by the metal and the ligand.

NOVEL OLEFIN NICKEL(0) COMPLEXES OF THE METHYL-DERIVATIVES OF METHYLENECYCLOPROPANE AND CYCLOPROPENE

The interaction of phosphine nickel complexes Ni(PPh3)3 and Ni(PPh3)2(η2-C2H4) with methyl derivatives of methylenecyclopropane and cyclopropene has been studied. The novel olefin complexes: (η2-2,2-dimethyl-1-methylenecyclopropane)bis(triphenylphosphine)nickel, (η2-1,3,3-trimethylcyclopropene)bis(triphenylphosphine)nickel and (η2-tetramethylcyclopropene)bis(triphenylphosphine)nickel have been prepared. The structure of the compounds obtained is discussed on the basis of the 1H and 31P{1H} NMR spectra. Comparative studies of the reactivities of the resulting complexes in the substitution reactions of η2-olefin ligands are described.