Axial ligand anation and aquation reactions in diplatinum(III) complexes. Comparison of aquation rates between hexachloroplatinate(IV) anion and diplatinum(III) chloro complexes having .mu.-phosphato or .mu.-pyrophosphito ligands

Elmehdawi, Ramadan Mohamed; Bryan, Samuel A.; Roundhill, D. Max

doi:10.1021/ja00308a020

Cited by 24 publications

(30 citation statements)

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“…The ''unconditional'' K 1 X and K 2 X values determined here are very different from the conditional ones reported before [47]. The formation constants of the reaction with thiocyanate ion, however, could not be determined because the complex(es) decomposed [32].…”

Section: Consecutive Formation Constants Of the Monohalo And Dihalo Ccontrasting

confidence: 91%

“…2À was not determined in the earlier studies [47,48]. In our study, the acid dissociation constant of the complex was determined in acidic aqueous solution as well as the formation constants (independent of pH) of the monohalo and dihalo complexes.…”

Section: Equilibrium Analysesmentioning

confidence: 64%

“…67% of the complex exsists as aquahydroxo-complex under the experimental conditions (pH ¼ 3) in the earlier research [47]. In the report, only the conditional formation constants of the monohalo and dihalo complexes were determined.…”

Section: Acid Dissociation Constant Of the Diaqua Complexmentioning

confidence: 89%

“…3. Equilibrium and kinetic studies on the axial water ligand substitution reaction of a hydrogenphosphato-bridged lantern-type platinum(III) binuclear complex with halide ions in acidic aqueous solution Historically, two kinetic and mechanistic studies on the ligand substitution reactions with halide ions were carried out for a lantern-type complex with hydrogenphosphate bridging ligands in 1986 [47], and in 2003 [48]. Their results (mechanisms) are, however, inconsistent with each other for the same reaction system.…”

Section: Kinetics For the Formation Of The Dihalo Complexesmentioning

confidence: 99%

“…2À with halide ions and pseudo-halide ion (Eq. (14)) in acidic aqueous solution under the conditions of C X À bC Pt [47,48],…”

Section: Consecutive Formation Constants Of the Monohalo And Dihalo Cmentioning

confidence: 99%

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Kinetics and mechanisms of the axial ligand substitution reactions of platinum(III) binuclear complexes with halide ions

Iwatsuki

Ishihara

Matsumoto

2006

Science and Technology of Advanced Materials

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The axial water ligand substitution reaction on the head-to-head (HH) and head-to-tail (HT) amidato-bridged cis-diammineplatinum(III) binuclear complexes, HH-and HT-[Pt 2 (NH 3 ) 4 (m-amidato) 2 (OH 2 ) 2 ] 4+ (amidato ¼ a-pyridonato, a-pyrrolidonato, or pivalamidato), with halide ions (X À ¼ Cl À , Br À ) in acidic aqueous solution reveals a consecutive 2-step kinetics under the pseudo first-order conditions of a large excess concentration of halide ion relative to that of the complex ðC X À bC Pt Þ, corresponding to formation of the monohalo (step 1) and the dihalo complexes (step 2). The first substitution step of all the HH and HT diaqua dimers consists of two parallel reaction pathways: one is the simple substituion path of one of the coordinated aqua ligands with X À , and the other is the replacement in the aquahydroxo complex which is the conjugate base of the diaqua dimer. In step 2, there are three reaction pathway patterns: the direct substitution path, the path via a coordinatively unsaturated intermediate, and the unusual path of OH À replacement.Step 2 proceeds via either one or two paths of the three depending on the nature of the halide ion as well as the bridging ligand. On the other hand, the substitution reaction of the hydrogenphosphato-bridged lantern-type complex, [Pt 2 (m-HPO 4 ) 4 (OH 2 ) 2 ] 2À proceeds in 1-step at C X À bC Pt , in which the first aqua ligand substitution to form the monohalo species is rate-determining and the monohalo species is in rapid equilibrium with the dihalo complex. The rate-determining step consists of parallel pathways similar to step 1 in the amidato-bridged complex systems. r

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Section: Consecutive Formation Constants Of the Monohalo And Dihalo Ccontrasting

confidence: 91%

Section: Equilibrium Analysesmentioning

confidence: 64%

Section: Acid Dissociation Constant Of the Diaqua Complexmentioning

confidence: 89%

Section: Kinetics For the Formation Of The Dihalo Complexesmentioning

confidence: 99%

“…2À with halide ions and pseudo-halide ion (Eq. (14)) in acidic aqueous solution under the conditions of C X À bC Pt [47,48],…”

Section: Consecutive Formation Constants Of the Monohalo And Dihalo Cmentioning

confidence: 99%

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Kinetics and mechanisms of the axial ligand substitution reactions of platinum(III) binuclear complexes with halide ions

Iwatsuki

Ishihara

Matsumoto

2006

Science and Technology of Advanced Materials

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Kinetic and Equilibrium Study on the Axial-Ligand Substitution Reaction of the Head-to-Tail α-Pyridonate-Bridgedcis-Diammineplatinum(III) Dinuclear Complex:trans Effect of the Axial Ligand through the Pt−Pt Bond to the Opposite Axial Ligand

Saeki

Hirano

Sasamoto

et al. 2001

Eur. J. Inorg. Chem.

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Acid dissociation constant of the axial aqua ligand in the Head-to-Tail (HT) α-pyridonate-bridged cis-diammineplatinum(III) dimer complex {[(H 2 O)Pt(NH 3 ) 2 (µ-C 5 H 4 NO) 2 Pt-(NH 3 ) 2 (H 2 O)] 4+ } was determined spectrophotometrically to be −log(K h1 /M) = 1.98±0.01 at 25°C and I = 2.00 M. Successive substitution reaction of the HT dimer with halide ions X − (X − = Cl − and Br − ) at the two axial sites to give monohalo and dihalo complexes was studied kinetically:Formation constants of the monohalo and dihalo complexes were determined spectrophotometrically to be log(K 1 Cl /M −1 ) = [a] 5.27±0.02 and log(K 2 Cl /M −1 ) = 3.83±0.01 for the reaction with Cl − , and log(K 1 Br /M −1 ) = 5.33±0.03 and log(K 2 Br /M −1 ) = 4.44±0.02 for the reaction with Br − . In the HT dimer having two equivalent platinum atoms, the deprotonation occurs to the water molecule on one of the two Pt atoms, whereas the first nucleophilic substitution with X − occurs to the other Pt atom. Substitution of the second water ligand with Cl − proceeds by a simple substitution path, whereas the second substitution with Br − proceeds by two parallel paths: one includes the dissociation of the axially coordinated water molecule followed by the Br − coordination, and the other is the simple one-step substitution path. The difference of the reaction paths is reasonably explained by the different trans effect of the halide ions exerted through the Pt−Pt bond to the other terminal Pt atom in the monohalo complexes.

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ChemInform Abstract: Axial Ligand Anation and Aquation Reactions in Diplatinum(III) Complexes.

Elmehdawi¹,

Bryan²,

Roundhill³

1986

Chemischer Informationsdienst

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Axial ligand anation and aquation reactions in diplatinum(III) complexes. Comparison of aquation rates between hexachloroplatinate(IV) anion and diplatinum(III) chloro complexes having .mu.-phosphato or .mu.-pyrophosphito ligands

Cited by 24 publications

References 1 publication

Kinetics and mechanisms of the axial ligand substitution reactions of platinum(III) binuclear complexes with halide ions

Kinetics and mechanisms of the axial ligand substitution reactions of platinum(III) binuclear complexes with halide ions

Kinetic and Equilibrium Study on the Axial-Ligand Substitution Reaction of the Head-to-Tail α-Pyridonate-Bridgedcis-Diammineplatinum(III) Dinuclear Complex:trans Effect of the Axial Ligand through the Pt−Pt Bond to the Opposite Axial Ligand

ChemInform Abstract: Axial Ligand Anation and Aquation Reactions in Diplatinum(III) Complexes.

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