Exhaustive oxidation of a nickel dithiolate complex: some mechanistic insights en route to sulfate formationElectronic supplementary information (ESI) available: ESI-MS spectra of 1, 3, 7, and 8. ESI-MS spectra of a sample taken during the oxygenation of 3, and a sample taken during the peroxidation of 1 with four equivalents of H2O2. Tables of crystallographic data and CIF files for 3, 7, and 8. CCDC reference numbers 828723828725. For ESI and crystallographic data in CIF or other electronic fo
A study of the step-wise oxidation of a Ni( ii ) diaminodithiolate complex through the formation of sulfate, the ultimate sulfur oxygenate, is reported. Controlled oxygenations or peroxidations of a neutral, planar, tetracoordinate, low-spin Ni( ii ) complex of a N 2 S 2 -donor ligand, ( N , N -dime...
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| Main Authors | , , , |
|---|---|
| Format | Journal Article |
| Language | English |
| Published |
22.12.2011
|
| Online Access | Get full text |
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| Summary: | A study of the step-wise oxidation of a Ni(
ii
) diaminodithiolate complex through the formation of sulfate, the ultimate sulfur oxygenate, is reported. Controlled oxygenations or peroxidations of a neutral, planar, tetracoordinate, low-spin Ni(
ii
) complex of a N
2
S
2
-donor ligand, (
N
,
N
-dimethyl-
N-N
-bis(2-mecaptoethyl)-1,3-propanediaminato) nickel(
ii
) (
1
), led to a series of sulfur oxygenates that have been isolated and characterized by ESI-MS and single-crystal X-ray diffraction. A monosulfenate complex (
2
) was detected by ESI-MS as a product of oxidation with one equivalent of H
2
O
2
. However, this complex proved too unstable to isolate. Reaction of the dithiolate (
1
) with two equivalents of H
2
O
2
or one O
2
molecule leads to the formation of a monosulfinate complex (
3
), which was isolated and fully characterized by crystallography. The oxidation product of the monosulfinate (
3
) produced with either O
2
or H
2
O
2
is an interesting dimeric complex containing both sulfonate and thiolate ligands (
4
), this complex was fully characterized by crystallography, details of which were reported earlier by us. A disulfonate complex (
7
) is produced by reaction of
1
in the presence of O
2
or by reaction with exactly six equivalents of H
2
O
2
. This complex was isolated and also fully characterized by crystallography. Possible intermediates in the conversion of the monosulfinate complex (
3
) to the disulfonate complex (
7
) include complexes with mixed sulfonate/sulfenate (
5
) or sulfonate/sulfinate (
6
) ligands. Complex
5
, a four-oxygen adduct of
1
, was not detected, but the sulfonate/sulfinate complex (
6
) was isolated and characterized. The oxidation chemistry of
1
is very different from that reported for other planar
cis
-N
2
S
2
Ni(
ii
) complexes including N,N-dimethyl-
N-N
-bis(2-mecaptoethyl)-1,3-ethylenediaminato) nickel(
ii
), (
8
), and N,N'-bis(mercaptoethyl)-1,5-diazacyclooctane nickel(
ii
). To address the structural aspects of the reactivity differences, the crystal structure of
8
was also determined. A comparison of the structures of planar Ni(
ii
) complexes containing
cis
-dithiolate ligands, strongly suggests that the differences in reactivity are determined in part by the degree of flexibility that is allowed by the NN' chelate ring.
The oxygenation or peroxidation of a square planar Ni(
ii
)
cis
-dithiolate complex occurs in a step-wise process, preferentially at one of the thiolates before the other, and ultimately leading to ligand decomposition and the formation of a sulfate salt. |
|---|---|
| Bibliography: | Tables of crystallographic data and CIF files for 10.1039/c1dt11032b ESI-MS spectra of a sample taken during the oxygenation of , CCDC reference numbers O 1 For ESI and crystallographic data in CIF or other electronic format see DOI 2 with four equivalents of H 3 and 7 828723828725 8 and a sample taken during the peroxidation of Electronic supplementary information (ESI) available: ESI-MS spectra of |
| ISSN: | 1477-9226 1477-9234 |
| DOI: | 10.1039/c1dt11032b |