V. V. Krivykh

Synthesis and spectral study of chelate alkenylarenedicarbonyl complexes of Cr, Mo and W

Abstract Irradiation of alkenylarene tricarbonyl-chromium, -molybdenum, and -tungsten compounds in which the double bond is separated from the arene moiety by a two- or three-atom bridge results in intramolecular cyclization to give stable chelate alkenylarenedicarbonylmetal complexes. Chelate complexes containing four-atom bridges have low stabilities, and those with monoatomic bridges were not formed at all. Irradiation of styrenetricarbonyl-chromium and -molybdenum leads to dinuclear tricarbonylmetal—dicarbonylmetal complexes. The chelate complexes obtained have been studied by IR, proton NMR, and 13C NMR spectroscopy. The electron density distributions and the stereochemistry of the complexes are discussed. With nonsymmetric arenes, diastereoisomers are formed; the predominant isomers have been isolated in the pure form. According to the proton NMR data the double bond in alkenylarenechromium chelates is parallel of nearly parallel to the arene ring plane.

Cationic Areneallyldicarbonylchromium complexes

Abstract The proton cleavage of chelate dicarbonylchromium complexes in the presence of benzyl and phenyl allyl ethers are shown to result in the formation of the formerly unknown cationic areneallyldicarbonylchromium complexes. We describe the general one step synthesis of these compounds upon ultra-violet irradiation of arenetricarbonylchromium compounds and allyl alcohol and its derivatives in the presence of hydrofluoroboric acid. We obtained the formerly unknown cationic arenedicarbonyl complexes with a π-oxyallyl ligand when we used propargyl alcohol in this reaction.

Mono-, di-, and tricyclic chelate chromium arenedifluorophosphite complexes

Abstract Difluorophosphites are shown to be able to replace all CO groups in arenetricarbonylchromium complexes under UV irradiation. New chromium chelates with polydentate arenedifluorophosphite ligands containing one, two, and three chelate cycles are reported. These are compared with analogous nonchelate phenyldifluorophosphite complexes. The structures of the complexes synthesized are proven by IR and 1 H, 19 F and 31 P NMR spectra and mass-spectrometry.

Chelate arenebis-phosphite carbonylchromium complexes

Abstract UV irradiation of arenetricarbonylchromium complexes containing OP(OR) 2 phosphorus atoms in the δ- or ϵ-positions of two side chains causes complete displacement of two CO ligands to give two-bridge chelate arenebis-phosphite tricarbonylchromium complexes. With phosphorus in the γ-position one-bridge chelate complexes only are formed. Intramolecular coordination of the second phosphorus atom does not occur because of steric hindrance. The reactions leading to the chelate complexes are compared with the similar reactions between mesitylenetricarbonylchromium and triphenylphosphite. The reactions terminate at the replacement of two groups under the conditions used in this work. The structures of the complexes isolated are proved by IR and 1 H and 31 P NMR spectra.

Protonation of triosmium clusters Os3(CO)9(μ−CO)(μ3−2σ,η2−HCCR) and Os3(μ−H)(CO)9(μ3−σ,2η2−CCR) (R = CH2OH, CMe2OH, C(Me) = CH2

Abstract Protonation of Os3(CO)(μ−CO(μ3−2σ,η2−HCCR) (R = CH2OH (1) R = CMe2OH (2) and Os3(μ−H)(CO)9(μ3−σ,2η2−CCR) (R = CH2OH (3), R = CMe2OH (4), R = C(Me) = CH2 (5)) affords cationic complexes with the 5e-and 6e-propargyl ligands [Os3(CO)9(μ−CO)(μ3−3σ,η2−HCCCR′2)]+ (R′ = H (6), R′ = Me ( 7 ) and [Os3(μ−H)(CO)9(μ3−2σ,2η2−CCR′2)+ ( R′ = H ( 8 ) , R′ = Me ( 9 ) respectively. Reactrions of the cationic complexes with PPh3 were studied. The treatment of solutions of complexes 6–9 with triphenylphosphine leads to the phosphonium derivatives of the Os3 clusters Os 3 ( CO ) 9 (μ 2 −2σ,η 2 - HC  CCR ′ 2 P + Ph 3 ) ( R ′ = H , (10); R ′ = Me, ( 11 )) as well as complexes Os 3 (μ- H(CO ) 9 (μ 3 −σ,2η 2 − P + Ph in3 CCCR ′ 2 ) ( R = H ( 12 , R ′ = Me ( 13 )) with the novel phosphonium allenyl ligand. The cluster Os3(CO)8(μ−CO){HC2[C(Me)CH2]COC[C(Me)CH2]CH} (4) synthesized and its X-ray study was carried out (R = 0.0504 for 5510 observed reflections). Crystals of 14 are triclinic, at 20°C: a = 8.591(2), b = 11.437(2), c = 12.642(3) A , α = 93.17(2), β = 104.67(2), γ = 101.83(2)°, V = 1168.6(4) A , d calc = 2.793 g cm −3 , Z = 2 , space group P 1 .

Investigation of the stereochemistry of transition metal allyl cationic complexes

Abstract Stereochemistry of transition metal-allyl cationic complexes synthesized by reaction of the corresponding metal carbonyls with allyl alcohol or a conjugated diene in the presence of a strong protonic acid has been investigated by means of NMR and IR spectroscopy. The number of isomers, as well as the position of substituents in the allyl ligands of complexes of the group 6 and 7 metals and iron, is determined by the formation of η2-diene complexes in the transoid conformation in which the diene is coordinated via a substituted or non-substituted double bond. The protonation products formed in the initial stage of the reactions of CpM(CO)2 (where M = Co, Rh, Ir) with acids lead to the mixtures of syn- and anti-crotyl isomers in their subsequent reactions with butadiene, the anti-isomers being transformed into syn-complexes on heating. The study of conformational isomerism of the half-sandwich allyl complexes has shown that the Cr, Mo, W, Mn and Re compounds of [LM(CO)2(allyl)]+ BF4− (where L = arene, cyclopentadienyl) exist in the form of equilibrium mixtures of exo- and endo-conformers, the endo-conformer prevailing in the case of Mo, W and Re; for [CpM(CO)(allyl)]+ BF4− (where M = Co, Rh, Ir), disappearance of the endo-isomer on heating has been observed.

Electrochemical substitution of a carbonyl group by a phosphorus ligand in arenechromium tricarbonyl complexes

Abstract Electrochemical oxidation of (η-1,3,5-Me3C6H3)Cr(CO)3 in the presence of P(OEt)3 with subsequent electrochemical reduction results in the formation of a (η-1,3,5-Me3C6H3)Cr(CO)2[P(OEt)3] and (η-1,3,5-Me3C6H3)Cr(CO)[P(OEt)3]2 mixture. Under similar conditions (η6-arene)Cr(CO)3, where arene = 3,5-Me2C6H3(CH2)2OPR2 (R = OEt,OPh,F), yields the corresponding arenephosphite chelate complexes.

Molecular structure of the chelate chromium complex with hexadentate 1,3,5-(F2POCH2CH2)3C6H3 ligand

Abstract The new tri-bridged chromium complex 1,3,5-(F2POCH2CH2)3C6H3Cr has been synthesized and its structure has been established by X-ray analysis.

Molecular structure of an areneolefindicarbonyl-chromium chelate complex with (2,5-dimethylbenzyl)-allyl ether as the chelate ligand

Abstract (2,5-Dimethylbenzyl)allyl ether produces two diastereomeric pairs of enantiomers with η 8 coordination of the Cr(CO) 2 group; the structure of the principal enantiomeric pair is established by complete X-ray analysis.

Molecular structure of the chelate complex (3,5-dimethylbenzyl)diphenylphosphitodicarbonyl-chromium

Abstract The chelate phosphitoalkylarenedicarbonylchromium complex has been studied by single-crystal X-ray diffraction. The presence of the short bridge (CH2O) leads to noticeable distortions of the molecular geometry which may be the reason why complexes of this type containing one more chelate cycle of the same size could not be isolated. The CrP bond in the complex 2.201 A, is the shortest CrP bond reported thus far.