Anation Reactions of Cobalt(III) complexes

Ghosh, Manik C.; Bhattacharya, Prabir; Banerjee, Pradyot

doi:10.1016/0010-8545(88)80012-2

Cited by 11 publications

(2 citation statements)

References 109 publications

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“…While the hexaamminecobalt(III) cation is exceptionally robust toward ligand exchange, the ammonia ligands of the isoelectronic pentaamminemethylcobalt(III) cation are readily exchanged with other simple inorganic ligands. This originates presumably from the well-established trans effect of an alkyl group . It is evident from the X-ray crystal structures of the title compounds ( vide infra ) that the significant trans influence also is reflected in the bond lengths.…”

Section: Resultsmentioning

confidence: 98%

NMR Spectroscopic Characterization of Methylcobalt(III) Compounds with Classical Ligands. Crystal Structures of [Co(NH₃)₅(CH₃)]S₂O₆,trans-[Co(en)₂(NH₃)(CH₃)]S₂O₆(en = 1,2-Ethanediamine), and [Co(NH₃)₆]-mer,trans-[Co(NO₂)₃(NH₃)₂(CH₃)]₂-trans- [Co(NO₂)₄(NH₃
Kofod
¹
,
Harris
²
,
Larsen
³

1997
Inorg. Chem.
46
6
15
0
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A series of methylcobalt(III) compounds with solely classical ligands such as NH(3), H(2)O, NO(2)(-), CN(-), and 1,2-ethanediamine (en) has been prepared by ligand substitution of the pentaamminemethylcobalt(III) cation. The new compounds have been characterized by (1)H, (13)C, and (59)Co nuclear magnetic resonance spectroscopy and by absorption spectroscopy. Single-crystal X-ray structure determinations at 122.0(5) K were performed on [Co(NH(3))(5)(CH(3))]S(2)O(6) (1), trans-[Co(en)(2)(NH(3))(CH(3))]S(2)O(6) (2), and [Co(NH(3))(6)]-mer,trans-[Co(NO(2))(3)(NH(3))(2)(CH(3))](2)-trans-[Co(NO(2))(4)(NH(3))(2)] (3). Compound 1 is monoclinic, P2(1)/n, with cell dimensions a = 6.4856(9) Å, b = 18.0720(11) Å, c = 9.7854(14) Å, and beta = 98.280(13) degrees. Compound 2 is orthorhombic, P2(1)2(1)2, with cell dimensions a = 12.211(3) Å, b = 10.107(3) Å, and c = 11.514(3) Å. Compound 3 is monoclinic, P2(1)/n, with cell dimensions a = 8.390(2) Å, b = 8.970(3) Å, c = 20.650(9) Å, and beta = 91.29(2) degrees. Virtually identical Co-C distances in the range 1.980-1.984 Å are found in the three compounds. The methyl group exerts a strong trans influence. The largest relative elongation of the bond to the trans ligand is 0.170 Å in the trans-[Co(en)(2)(NH(3))(CH(3))](2+) cation. The structural trans influence appears to decrease with the overall charge of the coordination compound. Estimates of the scalar one-bond cobalt-carbon coupling constants, (1)J(Co)(-)(C), in the pentacyanomethylcobalt(III) anion was obtained by line shape analysis, yielding values of 127, 95, and 62 Hz for the cis cyano groups, the trans cyano group, and the methyl group, respectively.

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Section: Resultsmentioning

confidence: 98%

NMR Spectroscopic Characterization of Methylcobalt(III) Compounds with Classical Ligands. Crystal Structures of [Co(NH₃)₅(CH₃)]S₂O₆,trans-[Co(en)₂(NH₃)(CH₃)]S₂O₆(en = 1,2-Ethanediamine), and [Co(NH₃)₆]-mer,trans-[Co(NO₂)₃(NH₃)₂(CH₃)]₂-trans- [Co(NO₂)₄(NH₃
Kofod
¹
,
Harris
²
,
Larsen
³

1997
Inorg. Chem.
46
6
15
0
View full text Add to dashboard Cite

show abstract

“…The mechanisms of substitution processes in inorganic transition-metal complexes are well established (1,2); many inorganic chemistry textbooks include a chapter about the subject (3,4). Given the quantity of information available on Co(III)-pentaammine complexes (5)(6)(7), as well as the inertness derived from their t 2g 6 electronic configuration, most of the information given to undergraduate students is based on their dissociatively activated substitution reactivity (8,9). A special emphasis is usually given to the distinction between spontaneous and accelerated substitution processes; the description of the stoichiometry, composition, and bond distribution of the different transition states is generally comprehensive.…”

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confidence: 99%