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Synthesis and Reactivity of Cobalt Complexes with Pendant Nitrogen Functional Groups
Author(s) -
Li Longjin,
Han Shuang,
Li Qiang,
Chen Zhenxia,
Pang Zhen
Publication year - 2007
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.200700447
Subject(s) - chemistry , cyclopentadienyl complex , cobalt , iodide , chelation , reactivity (psychology) , piperidine , side chain , dichloromethane , medicinal chemistry , polymer chemistry , hydrogen bond , stereochemistry , inorganic chemistry , organic chemistry , catalysis , molecule , medicine , polymer , alternative medicine , pathology , solvent
Several derivatives of cyclopentadienylcobalt complexes having a pendant amino‐functionalised side chain (Cp′) are described, the cyclopentadienyl ligands being (2‐aminoethyl)cyclopentadienyl, (2‐piperidinoethyl)cyclopentadienyl,1‐(2‐piperidinoethyl)‐2,3,4,5‐tetraisopropylcyclopentadienyland 2‐picolylcyclopentadienyl. Chelation by the amino‐functionalised side chain occurred when the Cp*‐cobalt(I) dicarbonyl complexes 5 , 6 , 7 and 8 were oxidised by iodine, thereby forming the corresponding Cp*‐cobalt(III) chelates 9 , 10 , 11 and 12 , respectively, through the diiodocarbonyl intermediates 5′ , 6′ , 7′ and 8′ , respectively. The stabilities of the intermediates differ greatly due to the different amino functions in the pendant side chain. Structural studies of 9 , 10 and 12 were carried out and the correlation of the I–Co–I angles and the repulsive forces from the amino‐functionalised groups with the stabilities of the intermediates is discussed. The diiodocarbonyl‐η 5 ‐(2‐piperidinylethyl)cyclopentadienylcobalt(III) intermediate 6′ becomes reduced to 6 by the CO released upon chelation of the former when the concentration of CO reaches about 0.088 mol L −1 . The chelated piperidine group in 10 could be easily replaced by triphenylphosphane to form the diiodotriphenylphosphanyl‐η 5 ‐(2‐piperidinioethyl)cyclopentadienylcobalt(III) iodide dichloromethane solvate 13 in the presence of hydrogen iodide. A strong N–H ··· I hydrogen bond with an N ··· I distance of 3.414(14) Å and a D–H ··· A angle of 164.1° were found in 13 . (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)