The tri-μ-amido-bis[triammineplatinum(IV)] cation; preparation, structure and acidity

Frank, Walter; Heck, Ludwig; Müller‐Becker, Stefan; Raber, Thomas

doi:10.1016/s0020-1693(97)05635-1

Cited by 11 publications

(10 citation statements)

References 7 publications

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“…106–109 In platinum(IV) complexes, the protons of these groups resonate farther downfield, between 4.5 and 5.5 ppm. 110,111 Based on the chemical shifts observed for the µ-NH 2 ligands in [ 4 ] 4+ , it appears that the metal-metal bonded diplatinum(III) centers produce deshielding similar that in the more electron-deficient platinum(IV) centers. The CH 3 resonances of the two inequivalent bridging acetate ligands appear at 2.58 and 2.30 ppm.…”

Section: Resultsmentioning

confidence: 99%

Acetate-Bridged Platinum(III) Complexes Derived from Cisplatin

Wilson

Lippard

2012

Inorg. Chem.

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Oxidation of the acetate-bridged half-lantern platinum(II) complex, cis-[PtII(NH3)2(µ-OAc)2PtII(NH3)2](NO3)2, [1](NO3)2, with iodobenzene dichloride or bromine generates the halide-capped platinum(III) species, cis-[XPtIII(NH3)2(µ-OAc)2PtIII(NH3)2X](NO3)2, where X is Cl in [2](NO3)2, or Br in [3](NO3)2, respectively. These three complexes, characterized structurally by X-ray crystallography, feature short (≈ 2.6 Å) Pt–Pt separations, consistent with formation of a formal metal-metal bond upon oxidation. Elongated axial Pt–X distances occur, reflecting the strong trans influence of the metal-metal bond. The three structures are compared to those of other known dinuclear platinum complexes. A combination of 1H, 13C, 14N, and 195Pt NMR spectroscopy was used to characterize [1]2+–[3]2+ in solution. All resonances shift downfield upon oxidation of [1]2+ to [2]2+ and [3]2+. For the platinum(III) complexes, the 14N and 195Pt resonances exhibit decreased linewidths by comparison to those of [1]2+. Density functional theory (DFT) calculations suggest that the decrease in 14N linewidth arises from a diminished electric field gradient (EFG) at the 14N nuclei in the higher valent compounds. The oxidation of [1](NO3)2 with the alternative oxidizing agent, bis(trifluoroacetoxy) iodobenzene, affords the novel tetranuclear complex, cis-[(O2CCF3)PtIII(NH3)2(µ-OAc)2PtIII(NH3)(µ-NH2)]2(NO3)4, [4](NO3)4, also characterized structurally by X-ray crystallography. In solution, this complex exists as a mixture of species, the identities of which are proposed.

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Section: Resultsmentioning

confidence: 99%

Acetate-Bridged Platinum(III) Complexes Derived from Cisplatin

Wilson

Lippard

2012

Inorg. Chem.

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“…The remaining two resonances occur downfield of where the ammine signals from carboplatin appear, consistent with terminal ammines or bridging amides bound to a Pt(IV) center. 48,49 The integrated intensities of these downfield resonances indicate that they arise from three and two protons, respectively, when compared to the integrated intensities of those arising from the cyclobutane fragment of the CBDCA ligand. Moreover, the yellow color of the product differed significantly from the red or purple hue that would be expected for the desired diiodide compound.…”

Section: Oxidative Halogenation Of Carboplatinmentioning

confidence: 99%

“…There are examples of amido-bridged complexes of platinum(II), [69][70][71][72] platinum(III), 39,73 and platinum(IV) 48,49 that have been characterized spectroscopically and crystallographically. In these systems, crystallographic characterization often requires careful consideration.…”

Section: Crystal Structure Of 7•3dmf•et 2 Omentioning

confidence: 99%

Oxidative halogenation of cisplatin and carboplatin: synthesis, spectroscopy, and crystal and molecular structures of Pt(iv) prodrugs

et al. 2015

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A series of Pt(IV) prodrugs has been obtained by oxidative halogenation of either cisplatin or carboplatin. Iodobenzene dichloride is a general reagent that cleanly provides prodrugs bearing axial chlorides without the need to prepare intervening Pt(IV) intermediates or handle chlorine gas. Elemental bromine and iodine afford Pt(IV) compounds as well, although in the case of the iodine-mediated oxidation of carboplatin, an amido-bridged Pt(IV) side product also formed. A detailed analysis of the changes in spectroscopic and structural parameters induced by varying the axial halide is presented. A number of recurring motifs are observed in the solid state structures of these compounds.

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“…Identification X-Ray diffraction, 13 C-{ 1 H} NMR and electrospray mass spectrometry (ESMS, a very useful technique for the characterization of bridged, multiply charged complexes 19 ) have been the primary means of identification of the three complexes 1, 2 and 3 isolated as perchlorates after treatment of [Co(tacn)(O 3 SCF 3 ) 3 ] with KNH 2 (mol fraction 1 : 1.4) in liquid ammonia at 100 °C for three days. In the following we describe these compounds in more detail including the behaviour of the amido-bridged complexes 2 and 3 in perchloric acid.…”

Section: Resultsmentioning

confidence: 99%

“…8,9 In case of the diamido-bridged species this is a result of studies by Ludwig Heck and co-workers in the 1980s and 1990s on the formation of amido bridges for a series of metal ammines, first of all those of chromium(III), 10 cobalt(III), 11,12 rhodium(III) 12 and platinum(IV). 13 Another result of their work was the synthesis and structural characterization of the first triply amido-bridged metal complex, [(NH 3 ) 3 Co(-NH 2 ) 3 Co(NH 3 ) 3 ] 3+ [from Co(NH 3 ) 6 3+ and KNH 2 in NH 3 (l)]. 11 In water this complex is remarkably robust, and the first bridge cleavage was investigated at [H + ] 0.005-0.5 M, where the observed rate constant increases linearly with [H + ] (k obs ≈ 0.45[H + ] s −1 at 35 °C in 1 M (Na,H)NO 3 (extrapolated)).…”

Section: Introductionmentioning

confidence: 99%

Dinuclear 1,4,7-triazacyclononane (tacn) complexes of cobalt(iii) with amido and tacn bridges. Synthesis, characterization and reversible acid-accelerated bridge cleavage

et al. 2004

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Amido-bridged dinuclear cobalt(III) complexes with 1,4,7-triazacyclononane (tacn) were synthesized from [Co(tacn)(O3SCF3)3] by treatment with potassium amide in liquid ammonia at 100 degrees C. Two isomeric triply bridged complexes, [(tacn)Co(mu-NH2)3Co(tacn)]3+ and [(tacn)Co(mu-NH2)2[mu-tacn(-H)]Co(NH3)]3+, were isolated as perchlorates, and the crystal structure of the perrhenate of the latter complex was determined by X-ray diffraction. In this compound a nitrogen atom (deprotonated) from one of the tacn ligands forms a third bridge together with two amido bridges. In 1.0 M (Na,H)ClO4 ([H+] 0.1-1.0 M) the two isomers undergo acid-accelerated amido bridge cleavage, as earlier found for chromium(III) analogues, in spite of the fact that such bridges are co-ordinatively saturated. The triamido-bridged isomer is in this acid medium in equilibrium with [(H2O)(tacn)Co(mu-NH2)2Co(tacn)(NH3)]4+. An isolated perchlorate of this complex appeared to be the salt of the trans-ammineaqua isomer as determined by X-ray diffraction. Equilibration from both sides fits the first-order rate constant dependence k(obs)=6.2(3) x 10(-5)[H+] + 2.1(2) x 10(-5)(s(-1)) at 40 degrees C. Prolonged treatment of the two triply bridged isomers in 1.0 M HClO4 at elevated temperature produces primarily triply bridged dinuclear species where one or two amido bridges have been replaced by hydroxo bridges.

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The tri-μ-amido-bis[triammineplatinum(IV)] cation; preparation, structure and acidity

Cited by 11 publications

References 7 publications

Acetate-Bridged Platinum(III) Complexes Derived from Cisplatin

Acetate-Bridged Platinum(III) Complexes Derived from Cisplatin

Oxidative halogenation of cisplatin and carboplatin: synthesis, spectroscopy, and crystal and molecular structures of Pt(iv) prodrugs

Dinuclear 1,4,7-triazacyclononane (tacn) complexes of cobalt(iii) with amido and tacn bridges. Synthesis, characterization and reversible acid-accelerated bridge cleavage

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