Crystal and molecular structures of three [Rh2(O(E)CR)4(C5H5N)2] compounds (ES, RCMe3, Ph; EO, R=Ph)

Mehmet, Nilgun; Tocher, Derek A.

doi:10.1016/s0020-1693(00)80920-2

Cited by 23 publications

(9 citation statements)

References 28 publications

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“…The Rh-S bond distances in ( 4DL + 6H 2 O) (2.255(3) – 2.266(3) Å) are similar to those reported for other dirhodium(II) complexes with S -donor ligands in equatorial positions (2.260 – 2.279 Å), 56, 63-65 but considerably shorter than the average Rh-S axial distances (2.58 ± 0.02 Å) obtained from EXAFS for solution A containing [Rh 2 (AcO) 4 (HMet) 1-2 ] (see Table 2).…”

Section: Resultssupporting

confidence: 80%

Methionine Binding to Dirhodium(II) Tetraacetate

et al. 2018

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The reaction between antitumor active dirhodium(II) tetraacetate and DL-methionine (HMet) was followed in aqueous solution and showed initially mixtures of 1:1 and 1:2 adducts [Rh2(AcO)4(HMet)(H2O)] (AcO− = CH3COO−) and [Rh2(AcO)4(HMet)2] formed at room temperature (RT), as evidenced by UV-vis spectroscopy and electrospray ionization mass spectrometry (ESI-MS). Rh K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy confirmed methionine thioether binding to the axial positions of the Rh2(AcO)4 cage structure. With excess HMet at RT stepwise displacement of the acetate groups was observed after some time using ESI-MS. Heating the solution to 40° for 24 h accelerated the substitution reaction leading to stable dirhodium(II) species with two acetate ligands displaced by two methionine groups. The crystal structure of the purple [RhII2(AcO)2(D-Met)(L-Met)]·6H2O compound obtained from the solution revealed tridentate coordination of the methionine ligands to the Rh(II) ions, with the thioether S atoms in equatorial positions. A minor amount of a light orange monomeric [RhIII(Met)2](AcO) complex also formed in the solution was isolated by size exclusion chromatography, and identified by ESI-MS. Crystals of [RhIII(D-Met)(L-Met)]Cl·3H2O were prepared by reacting RhCl3 and DL-HMet. The crystal structure showed tridentate binding of the methionine ligands to the Rh(III) ion in a trans-S,N,O arrangement.

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Section: Resultssupporting

confidence: 80%

Methionine Binding to Dirhodium(II) Tetraacetate

et al. 2018

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“…1 and Table 1). The values of the RhÐRh, RhÐN31 and mean RhÐO bonds are typical for this kind of compound, and are very close to those found for [Rh 2 (O 2 CPh) 4 (C 5 H 5 N) 2 ] [2.402 (1), 2.247 (4) and 2.041 (3) A Ê , respectively; Mehmet & Tocher, 1991] and [Rh 2 (TTB) 4 -(C 5 H 5 N) 2 ] [2.374 (1), 2.25 (4) and 2.050 (8) A Ê , respectively; Callot et al., 1989]. The distances and angles in (I) are also in the normal range for analogous amine bis-adducts (Cotton & Walton, 1992;Bonar-Law et al, 2000;Kitamura et al, 2000).…”

Section: Commentsupporting

confidence: 83%

“…The pyrazine (Pz) rings have a torsion angle of ca 18.5 around the RhÐN31 bond with respect to the plane of the nearer carboxylate group, and they are non-coplanar with the RhÐRh axis [RhÐRhÐN31 and RhÐN31ÐN32 angles of 174.57 (6) and 175.3 (1) , respectively], as has already been observed for other related compounds (Mehmet & Tocher, 1991;Cotton et al, 1992;Miyasaka et al, 2001), but not seen for Viossat's pyrazine-derivative bis-adduct (Viossat et al, 1993). No comparisons can be made with the [Rh 2 -(TTB) 4 (C 5 H 5 N) 2 ] compound, where the axial pyridines are highly disordered (Callot et al, 1989).…”

Section: Commentmentioning

confidence: 88%

“…Although molecular structures have been reported for many rhodium bis-adducts, they mainly involve aliphatic equatorial carboxylates (Christoph & Koh, 1979;Kitamura et al, 2000). As far as we know, the only published structures of dirhodium tetrabenzoate N-heterocyclic bis-adducts are those of [Rh 2 (O 2 CPh) 4 (C 5 H 5 N) 2 ] (Mehmet & Tocher, 1991) and [Rh 2 (TTB) 4 (C 5 H 5 N) 2 ], where TTB is 2,4,6-tri-p-tolylbenzoate (Callot et al, 1989). Pyrazine bis-adducts of rhodium tetracarboxylates are rare, and only one aliphatic pyrazine derivative, [Rh 2 (O 2 CCH 3 ) 4 {2-(1-pyrrolyl)pyrazine} 2 ], has been published (Viossat et al, 1993).…”

Section: Commentmentioning

confidence: 99%

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A pyrazine bis-adduct of a binuclear rhodium(II) carboxylate containing 3,4,5-triethoxybenzoate as the equatorial ligand

Castro¹,

Chaia²,

Piro³

et al. 2002

Acta Crystallogr C

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The title compound, tetrakis(μ‐3,4,5‐triethoxybenzoato‐κ2O:O′)bis[(pyrazine‐κN)rhodium(II)](Rh—Rh), [Rh2(C13H17O5)4(C4H4N2)2], crystallizes on an inversion centre in the triclinic space group . The equatorial carboxylate ligands bridge the two RhII atoms, giving a binuclear lantern‐like structure. The pyrazine molecules occupy the two axial coordination sites. The phenyl rings are tilted by ca 10° with respect to the attached carboxylate groups. The pyrazine planes have a torsion angle of ca 19° around the Rh—N bond with respect to the plane of the nearer carboxylate group and are not coplanar with the Rh—Rh bond.

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“…1). The Rh1-Rh1(Àx, Ày + 2, Àz) distance is 2.4116 (2) Å , which is comparable to the value of 2.402 (2) Å determined for the corresponding bispyridine complex [Rh 2 (bzt) 4 (py) 2 ] (Mehmet & Tocher, 1991). As a result of the sp 2 -hybridized nitrogen atoms, the rhodium nitrogen distance of 2.246 (4) in the latter molecule is shorter, compared to the value of 2.3083 (13) Å found for the title compound.…”

Section: Structure Descriptionsupporting

confidence: 75%