Structural Conversion of Sulfur-Bridged Polynuclear Complexes by Metal Replacement Reaction
| Project/Area Number |
07640736
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Inorganic chemistry
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| Research Institution | University of Tsukuba |
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Principal Investigator |
KONNO Takumi University of Tsukuba, Chemistry, Assistant Professor, 化学系, 講師 (50201497)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1996: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 1995: ¥1,400,000 (Direct Cost: ¥1,400,000)
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| Keywords | S-Bridged Polynuclear Complex / Strcutural Conversiton / Trigonal-bipyramidal Structure / Thiolate Ligand / Cadmium (II) Ion / Cobalt (III) Complex / Molecular Aggregation / Single-Crystal X-ray Analysis / 平面性金属イオン / 異常結合 / 配位子転移 / 自然分晶 / 絶対配置 / 結晶構造 |
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| Research Abstract |
Coordinated thiolato S atoms in mononuclear Co (III) complexes have been recognized to bind with other metal ions to form S-bridged polynuclear complexes. In fact, considerable progress has been made in the chemistry of S-bridged polynuclear complexes containing [Co (aet) (en) _2] ^<2+> or fac (S) - [Co (aet) _3] units (aet=2-aminoethanethiolate, en=ethylenediamine). On the other hand, no S-bridged polynuclear complexes containing [Co (aet) _2 (en)] ^+ units have long been studied, because of the difficulty in preparation of [Co (aet) _2 (en)] ^+ used as a starting mononuclear complex. We have recently found that the facile reaction of [Ni (aet) _2] with [CoCl_2 (en) _2] ^+ gives an S-bridged CO^<III>Ni^<II>Co^<III> trinuclear complex, [Ni {Co (aet) _2 (en)} _2] ^<4+> (1), in which the central Ni^<II> atom is coordinated by four Satoms from two C_2-cis (S) - [Co (aet) _2 (en)] ^+ units. In order to better understand the chemistry of S-bridged polynuclear complexes composed of octahedra
… More
l thiolato units, it is desirable to investigate other S-bridged polynuclear complexes composed of [Co (aet) _2 (en)] ^+ units.
In the present study, it was found that the replacement of the Ni^<II> atom in [Ni {Co (aet) _2 (en)} _2] Cl_4 is achieved by the reaction with excess CdCl_2 in water. However, the reaction product was not a corresponding S-bridged Co^<III>Cd^<II>Co^<III> trinuclear complex [Cd {Co (aet) _2 (en)} _2] ^<4+>, but a neutral dinuclear complex [CdCl_3 {Co (aet) _2 (en)}] (2), in which the Cd atom is situated in a trigonal-bipyramidal environment. When 2 was treated with a large amount of NaNO_3 in water, a cationic Co^<III>_4Cd^<II>_2 hexanuclear complex [Cd_2Cl {Co (aet) _2 (en)} _4] ^<7+> (3) was produced. In 3 each Cd^<II> atom also adopts a trigonal-bipyramidal geometry, coordinated by a bridging Cl atom besides four S atoms from the two C_2-cis (S)- [Co (aet) _2 (en)] ^+ units. Attempts to remove the bridging Cl atom from 3 by treating with a large amount of NaNO_3 in water were unsuccessful. Accordingly, it is reasonable to assume that the Co^<III>Cd^<II> polynuclear structures composed of C_2-cis (S) - [Co (aet) _2 (en)] ^+ units are stabilized by the preference of Cd (II) for the trigonal-bipyramidal geometry. The large covalent radius of the Cd^<II> atom and the small S-Cd-S bite angle restricted by the C_2-cis (S) - [Co (aet) _2 (en)] ^+ metalloligand seem to be responsible for this geometrical preference. Less
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Report
(3 results)
Research Products
(9 results)
