Synthesis, characterization and catalytic/antibacterial activity studies of ɳ⁵₋ cyclopentadienyl dicarbonyl ruthenium(II) amine complexes.
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Date
2015
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Abstract
The reaction of (η⁵-C₅H₅)Ru(CO)₂I and AgBF₄ in the ratio of 1:1 in methylene chloride afforded the iodo-bridged ruthenium complex, [(η⁵-C₅H₅)Ru(CO)₂]₂I. Two polymorphs, I and II, of the complex [(η⁵-C₅H₅)Ru(CO)₂]₂I were isolated. Polymorph I crystallized in the monoclinic P2/c space group with a = 12.0982(5) Å, b = 9.7923(4) Å, c = 15.5321(6) Å, β = 102.9880(10)°, while polymorph II crystallized in the monoclinic P2₁/c with a = 7.00560(10) Å, b = 14.1446(3) Å, c = 18.2226(3) Å, β = 96.2390(10)°. The reaction of (η⁵-C₅H₅)Ru(CO)₂I and a slight excess of AgBF₄ in methylene chloride afforded the Lewis acid, [CpRu(CO)₂]⁺BF₄, which was subsequently reacted with slight excesses of 1-alkanamines, RNH₂, in dry dichloromethane affording the new water-soluble 1-alkanaminedicarbonyl(η⁵-cyclopentadienyl)ruthenium(II) tetrafluoroborate complexes, [CpRu(CO)₂NH₂R]⁺BF₄⁻ (Cp = η⁵-C₅H₅; R = CH₃, C₂H₅, C₃H₇, C₄H₉, C₅H₁₁ and C₆H₁₃). Complexes of the type, [CpRu(CO)₂L]⁺BF₄⁻, (L = C₆H₁₁NH₂, C₆H₅CH₂NH₂, C₆H₅CH(CH₃)NH₂, (CH₃)₂CHNH₂, CH₂CHCH₂NH₂, NH₂CH₂(C₆H₄)OCH₃, NH₂CH₂C₆H₄CN, NH₂(CH₃)₃C₆H₂) were also synthesized by the reaction of the Lewis acid, [CpRu(CO)₂]⁺BF₄, with the ligands, L.
The reaction of (η⁵-C₅(CH₃)₅)Ru(CO)₂I and a slight excess of AgBF₄ in methylene chloride afforded the Lewis acid, [Cp*Ru(CO)₂]⁺BF₄ (Cp* = η⁵-C₅(CH₃)₅), which was subsequently reacted with slight excesses of 1-alkanamine, RNH₂ (R = CH₃, C₂H₅, C₃H₇, C₄H₉, C₅H₁₁), in dry dichloromethane affording the new water-soluble complex salts, [Cp*Ru(CO)₂NH₂R]⁺BF₄⁻
The α,αʹ-diaminoalkane-bridged diruthenium complex salts [Rp₂NH₂(CH₂))nNH₂]Y₂ (Rp = CpRu(CO)₂, where Cp =η⁵-C₅H₅; n = 2, 3, 4 and 6; Y = BF₄ or SO₃CF₃) were synthesized by the reaction of the acetonitrile complexes, [RpNCCH₃]Y and NH₂(CH₂)nNH₂ (n = 2, 3,4 and 6) in the ratio of 2:1.
All the complexes synthesized in this study are new and were fully characterized by IR, NMR, elemental analysis and melting point. The crystal structures of 12 complexes were determined; they all feature a “pseudo-octahedral three-legged piano stool” structure in which the ruthenium centre was coordinated through a sigma bond to the amine N atom and two carbonyl ligands at the base of the stool and the cyclopentadienyl ring as the apex of the stool. Antimicrobial susceptibility tests were done for the α,αʹ-diaminoalkane-bridged diruthenium compounds, and some mononuclear complexes, [CpRu(CO)₂L]⁺BF₄⁻. Good antimicrobial activity against Gram-positive and Gram-negative bacteria, as well as mycobacterium, was
achieved. Furthermore, the complexes synthesized showed excellent catalytic activity in the oxidation of styrene to form benzaldehyde in very good yield.
Description
Ph. D. University of KwaZulu-Natal, Durban 2015.
Keywords
Ruthenium., Metal catalysts., Organometallic chemistry., Complex compounds., Theses--Chemistry., Ruthenium(II) amine complexes.