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Influence of nitrosyl coordination on the binding mode of quinaldate in selective ruthenium frameworks. Electronic structure and reactivity aspects

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Title Influence of nitrosyl coordination on the binding mode of quinaldate in selective ruthenium frameworks. Electronic structure and reactivity aspects
 
Creator CHOWDHURY, AD
DE, P
MOBIN, SM
LAHIRI, GK
 
Subject NO-CENTER-DOT
DENSITY-FUNCTIONAL THEORY
NITRIC-OXIDE DIOXYGENASE
REVERSIBLE BINDING
PHOTODYNAMIC THERAPY
ANCILLARY LIGANDS
CRYSTAL-STRUCTURE
IRON PORPHYRIN
PHOTOLABILE RUTHENIUM
SUPEROXIDE-DISMUTASE
 
Description The nitrosyl complexes, [Ru-II(trpy)(L)(NO+)Cl]BF4, [1] BF4, and [Ru-II(trpy)(L)(NO+)](BF4)(2), [2](BF4)(2), (trpy = 2,2':6',2 ''-terpyridine, L- = deprotonated form of unsymmetrical quinaldic acid) have been synthesized. Single crystal X-ray structures of [1]BF4 and [2](BF4)(2) reveal that in the former L- binds to the ruthenium ion selectively in a monodentate fashion through the O- donor whereas the usual bidentate mode of L- (O-, N donors) has been retained in [2](BF4)(2) with the same meridional configuration of trpy being seen in both. The Ru-NO group in [1] BF4 or [2](BF4)(2), exhibits almost linear (sp-hybridized form of NO+) geometry. The difference in bonding mode of the unsymmetrical quinaldate in [1]BF4 and [2](BF4)(2) has been reflected in their corresponding nu(NO)/nu(C-O) frequencies as well as in their NO based two-step reduction processes, {Ru-II-NO+} -> {Ru-II-NO center dot} and {Ru-II-NO center dot}->{Ru-II-NO-}. The close to bent geometry (sp(2)-hybridized form of NO center dot) of the one-electron reduced 1 or [2](+) is been reflected in their DFT optimized structures. The spin density plot of the reduced species reveals that NO is the primary spin-bearing center with slight delocalization onto the metal ion which has been reflected in its radical EPR spectrum. [1]+ and [2](2+) undergo facile photorelease of NO with significantly different k(NO) (s(-1)) and t(1/2) (s) values which eventually lead to the concomitant formation of the corresponding solvent species. The photoreleased NO center dot can be trapped as an Mb-NO adduct. The reduced species 1 selectively reacts with the molecular oxygen (O-2) at pH similar to 1 to yield the corresponding nitro species, [Ru-II(trpy)(L)(NO2)Cl](-).
 
Publisher ROYAL SOC CHEMISTRY
 
Date 2014-10-16T15:16:34Z
2014-10-16T15:16:34Z
2012
 
Type Article
 
Identifier RSC ADVANCES, 2(8)3437-3446
http://dx.doi.org/10.1039/c2ra00953f
http://dspace.library.iitb.ac.in/jspui/handle/100/15880
 
Language en