Synthesis and Structure of Bis(-cyclopentadienyl)vanadium(IV) 1,10-Phenanthroline and 2,2'-Bipyridine Compounds and Their Interactions
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- 作者：Phalguni Ghosh ; Ann T. Kotchevar ; Darin D. DuMez ; Sutapa Ghosh ; John Peiterson ; and Fatih M. Uckun
- 刊名：Inorganic Chemistry
- 出版年：1999
- 出版时间：August 9, 1999
- 年：1999
- 卷：38
- 期：16
- 页码：3730 - 3737
- 全文大小：136K
- 年卷期：v.38,no.16(August 9, 1999)
- ISSN：1520-510X
文摘
The reaction of in situ generated Cp2V(OTf)2 (Cp = cyclopentadienyl; OTf = O3SCF3) with excess1,10-phenanthroline and 2,2'-bipyridine yields the d1 vanadocene coordination compounds [Cp2V(phen)][OTf]2(1) and [Cp2V(bpy)][OTf]2 (2), respectively. The compounds have been characterized by UV-vis and EPRspectroscopy and by cyclic voltammetry. The complexes have relatively low vanadium(IV)-vanadium(III) reductionpotentials (-0.62 V vs Cp2Fe+/0 in acetonitrile). Structures of 1 and 2 have been determined by X-raycrystallography. Compound 1 crystallized in a monoclinic system, space group P21/n, with a = 10.2763(5) Å, b= 18.1646(9) Å, c = 13.5741(7) Å, 
= 99.4150(10)
, and Z = 4. Refinement of its structure by full-matrixleast-squares techniques gave final residuals R = 0.040 and Rw = 0.096. Compound 2 crystallized in a monoclinicsystem, space group P21/c, with a = 10.6451(6) Å, b = 18.3863(10) Å, c = 12.6993(7) Å, = 98.6220(10),and Z = 4. Refinement of its structure by full-matrix least-squares techniques gave final residuals R = 0.046 andRw = 0.101. The two nitrogen atoms and centroids of the two cyclopentadienyl rings for both compounds occupya distorted tetrahedral geometry around the vanadium(IV) center. The chelated ring plane is inclined closer toone of the neighboring Cp rings with the tilt more evident in 1 (~8) than 2 (~4). The membrane interactionsof these compounds and the titanium analogues, [Cp2Ti(phen)][OTf]2 (3) and [Cp2Ti(bpy)][OTf]2 (4), have beenstudied with zwitterionic unilamellar liposomes as artificial membranes. We show that the ability of metallocenesto enhance the permeability of a liposomal membrane depends on the hydrophobicity, as well as the size andplanarity of the ancillary chelated ligands, but not the nature of the central metal ion. Also provided is evidencethat metallocene-induced permeability changes in artificial membranes are not caused by lipid peroxidation.
= 99.4150(10), and Z = 4. Refinement of its structure by full-matrixleast-squares techniques gave final residuals R = 0.040 and Rw = 0.096. Compound 2 crystallized in a monoclinicsystem, space group P21/c, with a = 10.6451(6) Å, b = 18.3863(10) Å, c = 12.6993(7) Å, = 98.6220(10),and Z = 4. Refinement of its structure by full-matrix least-squares techniques gave final residuals R = 0.046 andRw = 0.101. The two nitrogen atoms and centroids of the two cyclopentadienyl rings for both compounds occupya distorted tetrahedral geometry around the vanadium(IV) center. The chelated ring plane is inclined closer toone of the neighboring Cp rings with the tilt more evident in 1 (~8) than 2 (~4). The membrane interactionsof these compounds and the titanium analogues, [Cp2Ti(phen)][OTf]2 (3) and [Cp2Ti(bpy)][OTf]2 (4), have beenstudied with zwitterionic unilamellar liposomes as artificial membranes. We show that the ability of metallocenesto enhance the permeability of a liposomal membrane depends on the hydrophobicity, as well as the size andplanarity of the ancillary chelated ligands, but not the nature of the central metal ion. Also provided is evidencethat metallocene-induced permeability changes in artificial membranes are not caused by lipid peroxidation.