Dithiochelates of the biscyclopentadienylvanadium(IV) moiety. I. Biscyclopentadienylvanadium(IV) xanthates

Casey, A. T.; Thackeray, J. R.

doi:10.1071/ch9722085

Cited by 24 publications

(4 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Both are close to the expected value for a d 1 system (μ eff = 1.72 μ B ). Most chelated complexes of vanadocene(IV) are synthesized via an oxidative pathway with vanadocene(II) and the appropriate organic substrates, ,,− but a few have been prepared through the direct substitution of the ancillary positions of the Cp 2 V IV ion. ,,, Compounds 1 and 2 were prepared using a method similar to that described for the titanium analogues, [Cp 2 Ti(phen)][OTf] 2 ( 3 ) and [Cp 2 Ti(bpy)][OTf] 2 ( 4 ) . Although the reaction to prepare the titanium complexes ( 3 and 4 ) was instantaneous, the reactions to obtain 1 and 2 required more than 12 h for completion.…”

Section: Resultsmentioning

confidence: 99%

“…Investigations into the coordination chemistry of vanadocene(IV) L 2 (L is a monodentate ligand) or vanadocene(IV) (L-L) (L-L is a bidentate ligand) complexes have been for the most part to delineate the electronic structures and bonding properties of these d 1 systems. − Their potential applications as catalysts, especially the use of vanadocene dihalides in olefin polymerization reactions, have been the subject of interest for the past several decades. , There has also been a growing interest in examining the biological effects − of vanadocene complexes and studying their chemistry under physiological conditions. − Recently, interest in the synthesis and characterization of new vanadocene(IV) complexes has grown due to the demonstration of their spermicidal activity and apoptosis-inducing properties. − These spermicidal vanadocene complexes caused depolarization in the mitocondrial membrane without disrupting the human sperm membranes. , These results encouraged us to synthesize new vanadocene(IV) complexes and examine their surface interactions with artificial membranes.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Synthesis and Structure of Bis(π-cyclopentadienyl)vanadium(IV) 1,10-Phenanthroline and 2,2‘-Bipyridine Compounds and Their Interactions with Artificial Membranes

et al. 1999

View full text Add to dashboard Cite

The reaction of in situ generated Cp(2)V(OTf)(2) (Cp = cyclopentadienyl; OTf = O(3)SCF(3)) with excess 1,10-phenanthroline and 2,2'-bipyridine yields the d(1) vanadocene coordination compounds [Cp(2)V(phen)][OTf](2) (1) and [Cp(2)V(bpy)][OTf](2) (2), respectively. The compounds have been characterized by UV-vis and EPR spectroscopy and by cyclic voltammetry. The complexes have relatively low vanadium(IV)-vanadium(III) reduction potentials (-0.62 V vs Cp(2)Fe(+/0) in acetonitrile). Structures of 1 and 2 have been determined by X-ray crystallography. Compound 1 crystallized in a monoclinic system, space group P2(1)/n, with a = 10.2763(5) Å, b = 18.1646(9) Å, c = 13.5741(7) Å, beta = 99.4150(10) degrees, and Z = 4. Refinement of its structure by full-matrix least-squares techniques gave final residuals R = 0.040 and R(w) = 0.096. Compound 2 crystallized in a monoclinic system, space group P2(1)/c, with a = 10.6451(6) Å, b = 18.3863(10) Å, c = 12.6993(7) Å, beta = 98.6220(10) degrees, and Z = 4. Refinement of its structure by full-matrix least-squares techniques gave final residuals R = 0.046 and R(w) = 0.101. The two nitrogen atoms and centroids of the two cyclopentadienyl rings for both compounds occupy a distorted tetrahedral geometry around the vanadium(IV) center. The chelated ring plane is inclined closer to one of the neighboring Cp rings with the tilt more evident in 1 ( approximately 8 degrees ) than 2 ( approximately 4 degrees ). The membrane interactions of these compounds and the titanium analogues, [Cp(2)Ti(phen)][OTf](2) (3) and [Cp(2)Ti(bpy)][OTf](2) (4), have been studied with zwitterionic unilamellar liposomes as artificial membranes. We show that the ability of metallocenes to enhance the permeability of a liposomal membrane depends on the hydrophobicity, as well as the size and planarity of the ancillary chelated ligands, but not the nature of the central metal ion. Also provided is evidence that metallocene-induced permeability changes in artificial membranes are not caused by lipid peroxidation.

show abstract

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synthesis and Structure of Bis(π-cyclopentadienyl)vanadium(IV) 1,10-Phenanthroline and 2,2‘-Bipyridine Compounds and Their Interactions with Artificial Membranes

et al. 1999

View full text Add to dashboard Cite

show abstract

“…All chemicals used were of reagent grade purity. Some compounds (see Tables III and IV) were prepared as described in the literature (33)(34)(35). Working electrodes used include the DME, the hanging mercury drop (HMDE, Metrohm BM-503), platinum, wax impregnated graphite, and glassy carbon electrodes.…”

mentioning

confidence: 99%

Direct measurement of Er1/2 with reversible and EC [electrochemical] electrode processes by second harmonic alternating current polarography and voltammetry

Bond¹,

Smith²

1974

Anal. Chem.

View full text Add to dashboard Cite

“…Experimental evidence herein indicates that this is not the case. In addition, based on the cyclic voltammetric measurements as well as from the characteristic sharp eight line spectral features in the EPR of the complexes, all of the vanadocene-chelated complexes studied retain their pseudotetrahedral-like structure in the liposomal matrices with respect to the central metal V(IV) ion …”

Section: Discussionmentioning

confidence: 94%

Interactions of Vanadocene(IV)-Chelated Complexes with Artificial Membranes

1998

View full text Add to dashboard Cite

The membrane interactions of five vanadocene(IV)-chelated complexes, which are very effective spermicidal agents, have been studied using zwitterionic and negative unilamellar liposomes. In permeability studies, bis(cyclopentadienyl)vanadium(IV) (2,2‘-bipyridine)trifluoromethanesulfonate (1) and bis(cyclopentadienyl)vanadium(IV) (phenyl benzohydroxamato)trifluoromethanesulfonate (2) cause the release of about 35% and 20% encapsulated carboxyfluorescein, respectively, in both types of liposomes, whereas the congeneric vanadocene derivatives of diethyl dithiocarbamate (3), acetyl acetonate (4), and catecholate (5) have little or no effect on the permeability. Of the five compounds, only 4 and 1 initiate peroxidation of the lipids. None of the vanadocene-chelated complexes cause appreciable liposome aggregation, fusion, or changes in packing order of the liposomes as observed from UV/vis spectroscopy, fluorescence energy resonance transfer, and fluorescence polarization studies. The ability of the two vanadocene derivatives (1 and 2) to cause the liposomes to become permeable is therefore not related to the extent of peroxidation of the lipids or to complete disruption of the membrane. We propose that these vanadocene-chelated complexes have unique configurational preferences which alter the membrane by intercalation, creating “leaky patches” in the liposomal membrane.

show abstract

Dithiochelates of the biscyclopentadienylvanadium(IV) moiety. I. Biscyclopentadienylvanadium(IV) xanthates

Cited by 24 publications

References 0 publications

Synthesis and Structure of Bis(π-cyclopentadienyl)vanadium(IV) 1,10-Phenanthroline and 2,2‘-Bipyridine Compounds and Their Interactions with Artificial Membranes

Synthesis and Structure of Bis(π-cyclopentadienyl)vanadium(IV) 1,10-Phenanthroline and 2,2‘-Bipyridine Compounds and Their Interactions with Artificial Membranes

Direct measurement of Er1/2 with reversible and EC [electrochemical] electrode processes by second harmonic alternating current polarography and voltammetry

Interactions of Vanadocene(IV)-Chelated Complexes with Artificial Membranes

Contact Info

Product

Resources

About