Publications by authors named "Bobby Ramdhanie"

The structural and physicochemical properties of the manganese-corrolazine (Cz) complexes (TBP8Cz)Mn(V)O (1) and (TBP8Cz)Mn(III) (2) (TBP = p-tert-butylphenyl) have been determined. Recrystallization of 2 from toluene/MeOH resulted in the crystal structure of (TBP8Cz)Mn(III)(CH3OH) (2 x MeOH). The packing diagram of 2 x MeOH reveals hydrogen bonds between MeOH axial ligands and meso N atoms of adjacent molecules.

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As part of our efforts to develop the transition metal chemistry of corrolazines, which are ring-contracted porphyrinoid species most closely related to corroles, the vanadium and copper complexes (TBP)(8)Cz(H)V(IV)O (1) and (TBP)(8)CzCu(III) (2) of the ligand octakis(para-tert-butylphenyl)corrolazine [(TBP)(8)Cz] have been synthesized. The coordination behavior, preferred oxidation states, and general redox properties of metallocorrolazines are of particular interest. The corrolazine ligand in 1 was shown to contain a labile proton by acid/base titration and IR spectroscopy, serving as a -2 ligand rather than as the usual -3 donor.

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The novel cobalt corrolazine (Cz) complexes (TBP)(8)CzCoCN (1) and (TBP)(8)CzCo(CCSiPh(3)) (2) have been synthesized and examined in light of the recent intense interest regarding the role of corrole ligands in stabilizing high oxidation states. In the case of 2, the molecular structure has been determined by X-ray crystallography, revealing a short Co[bond]C distance of 1.831(4) A and an intermolecular pi-stacking interaction between Cz ring planes, and this structure has been analyzed in regards to the electronic configuration.

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The reaction between (TBP)8(Cz)Mn(III) (1) and the oxygen atom donors iodosylbenzene (PhIO) or p-cyanodimethylaniline-N-oxide (CDMANO) leads to the manganese(V)-oxo complex (TBP)8(Cz)Mn(V)O (2), which has been isolated and characterized previously. Under catalytic conditions with 1 as added catalyst and PhIO as oxidant, both sulfoxidation of PhSMe and epoxidation of cis-stilbene is observed, whereas with CDMANO no sulfoxidation takes place, suggesting that 2 is not the active oxidant. Examination of the independent reactivity of isolated 2 toward PhSMe and cis-stilbene supports this conclusion.

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The synthesis and characterization of an oxomanganese(V) corrolazine, (TBP)8(Cz)Mn(V)O (2), are reported. This remarkably stable high-valent complex is obtained from the stoichiometric reaction of (TBP)8(Cz)Mn(III) (1) with m-CPBA and is easily purified by standard chromatographic methods on silica gel at room temperature. Complex 2 exhibits a diamagnetic 1H NMR spectrum indicative of a low-spin d2 Mn(V)O species.

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The syntheses of the first transition metal corrolazine complexes, in which the meso carbon atoms of a corrole framework have been replaced by N atoms, are reported. Metalation of the corrolazine [(TBP)(8)CzH(3)] (TBP = 4-tert-butylphenyl) (1) with Co(acac)(2) gives [(TBP)(8)CzCo(III)] (2) in good yield. Addition of PPh(3) to 2 in pyridine results in the formation of [(TBP)(8)CzCo(III)(PPh(3))] (3), which was characterized by X-ray crystallography.

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