Koordinativ ungesättigte Platin(IV)-Verbindungen: von postulierten Intermediaten zu den ersten strukturell charakterisierten Komplexen

Puddephatt, Richard J.

doi:10.1002/1521-3757(20020118)114:2<271::aid-ange271>3.0.co;2-q

Cited by 10 publications

(2 citation statements)

References 63 publications

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“…It must be admitted that the spectroscopic features (Table 4) and most aspects of the chemical behavior of 16 would, in principle, also be in keeping with the solvent‐free, five‐coordinate species [Pt(C 6 F 5 ) 4 Br] − . Although they have often been suggested as key intermediates in reductive‐elimination processes,30 unsaturated (16‐electron) five‐coordinate Pt IV derivatives have only recently been isolated and structurally characterized 31. The assumption of a five‐coordinate structure for intermediate 16 does not explain why the Br − ion manages to enter the Pt coordination sphere in CH 2 Cl 2 at −80 °C, but fails in CHCl 3 at −55 °C.…”

Section: Resultsmentioning

confidence: 99%

Oxidative Addition of Halogens to Homoleptic Perfluoromethyl or Perfluorophenyl Derivatives of Platinum(II): A Comparative Study

Menjón¹,

Martínez-Salvador²,

Gómez‐Saso³

et al. 2009

Chemistry A European J

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Chlorocarbon solvents (solv=CH(2)Cl(2), CHCl(3)) are suggested to play an active role in the oxidative addition of halogens, X(2) (X=Cl, Br, I), to homoleptic d(8) perfluoromethyl and -phenyl platinum(II) species [Pt(R(F))(4)](2-) (R(F)=CF(3), C(6)F(5)). The perfluoromethyl group, CF(3), has been found to be considerably less prone to undergo reductive elimination processes, and is, therefore, more suitable for stabilizing organoplatinum(IV) derivatives (see scheme).The equilibrium geometries of the homoleptic perfluorinated organoplatinate(II) anions [Pt(CF(3))(4)](2-) and [Pt(C(6)F(5))(4)](2-) have been computed at the B3P86/LANL2DZ level of theory. Remarkably good agreement with the experimentally determined structures has been obtained by X-ray diffraction methods. The reactivity of [NBu(4)](2)[Pt(CF(3))(4)] (1) towards halogens (Cl(2), Br(2), and I(2)) has been investigated by using a combined experimental and theoretical approach. The perfluoromethyl derivative 1 has been found to undergo clean oxidative addition of the three halogens under investigation, giving rise to [NBu(4)](2)[trans-Pt(CF(3))(4)X(2)] (X=Cl (7), Br (10), I (13)) in a quantitative and stereoselective way. In the low-temperature reaction of the perfluorophenyl derivative [NBu(4)](2)[Pt(C(6)F(5))(4)] (3) with Cl(2) or Br(2), the corresponding oxidative-addition products [NBu(4)](2)[trans-Pt(C(6)F(5))(4)X(2)] (X=Cl (14), Br (15)) can also be obtained. In the case in which X=Br and working in CHCl(3) at -55 degrees C, it has been possible to detect the formation of an intermediate species to which we assign the formula [trans-Pt(C(6)F(5))(4)Br(ClCHCl(2))](-) (16). The solvento complex 16 is thermally unstable and prone to undergo reductive elimination of C(6)F(5)--C(6)F(5). In the presence of PhCN, complex [NBu(4)][trans-Pt(C(6)F(5))(4)Br(NCPh)] (17) was isolated and structurally characterized. The reaction of 3 with I(2) gave no organoplatinum(IV) compound. Our comparative study reveals that the CF(3) group is especially suited to stabilize organometallic compounds in high oxidation states. This ability can be attributed to a combination of factors: its hardness, its high group electronegativity, its small size, and its reluctance to undergo reductive elimination processes.

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Section: Resultsmentioning

confidence: 99%

Oxidative Addition of Halogens to Homoleptic Perfluoromethyl or Perfluorophenyl Derivatives of Platinum(II): A Comparative Study

Menjón¹,

Martínez-Salvador²,

Gómez‐Saso³

et al. 2009

Chemistry A European J

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“…When the solutions containing either 5 or 6 are gently heated (40 °C) under Ar for a few minutes, the equilibrium completely shifts to the left as a result of the deprotonation of an agostic o ‐methyl group and associated H 2 extrusion. In the reversible PtC hydrogenolysis, H 2 probably replaces the agostic o‐ methyl group, which leads to a transient cationic dihydrogen‐cyclometalated platinum( II ) complex that may be in equilibrium with the 16‐electron platinum( IV ) dihydrido species 1j. 19 Interestingly, Milstein and co‐workers have recently reported the opening of a platinum( II ) metallacycle complex by reaction with dihydrogen, but under harsher conditions 20…”

Section: Methodsmentioning

confidence: 99%

Novel T‐Shaped 14‐Electron Platinum(II) Complexes Stabilized by One Agostic Interaction

et al. 2003

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The stereoelectronic properties of the PR2(2,6‐Me2C6H3) (R=Ph, Cy) ligand can be used to stabilize an unprecedented class of 14‐electron platinum(II) complexes. The X‐ray analysis of the cyclometalated cyclohexyl derivative reveals an agostic interaction between the Pt center and an o‐methyl moiety (see picture). The fast and reversible formation of three‐coordinate platinum–hydrido complexes occurs by reaction with H2, and is achieved through the cleavage of a platinum–carbon bond.

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A Pseudotetrahedral, High‐Oxidation‐State Organonickel Compound: Synthesis and Structure of Bromotris(1‐norbornyl)nickel(IV)

Dimitrov

Linden

2003

Angewandte Chemie

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The organometallic chemistry of late transition metals in high oxidation states has been of considerable interest because of its relevance to certain catalytic reactions. [1][2][3][4] Organonickel compounds in the formal oxidation state + 4 have been obtained by the oxidation of decamethylnickelocene [5] and in a trinickelacarborane complex.[6] The first examples of octahedral diorganonickel(iv) compounds containing sbonded methyl and acylphenolato ligands were reported only recently.[7] The occurrence of tetracoordinate organonickel(iv) intermediates has been proposed in some cases, [8] but there are no previous reports of the isolation of a tetrahedral nickel(iv) compound containing s-bonded organic ligands. Herein we report the preparation of a tris(1-norbornyl)nickelate(ii) complex and its oxidation, which results in the formation of a diamagnetic pseudotetrahedral triorganonickel(iv) compound. The tetrakis(1-norbornyl) compounds of the first-row metals, with the exception of nickel, are rare examples of high oxidation state homoleptic transition-metal alkyl complexes with extraordinarily high stability.[9]Previously, we prepared several 1-norbonyl complexes of Ni II , which include the nickelate(ii) salt Li[CpNi(1-nor) 2 ] (Cp = C 5 H 5 ), starting from nickelocene.[10] For the preparation of the tris(1-norbornyl)nickel(ii) complex anion we now started from the pale blue compound [nBu 4 N] 2 [Ni IIBr 4 ] (1). The reaction of 1 with three equivalents of 1-norbornyllithium (2) in THF at À60 8C gave a blue-green solution of the anionic complex 3 (Scheme 1). The reaction with four equivalents of 2 also produced 3 and not the tetrakis(1-norbonyl)nickel(ii) complex, as was demonstrated by a subsequent transformation. Note that all previously reported nickel complexes of the type Li 2 [Ni II

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Koordinativ ungesättigte Platin(IV)-Verbindungen: von postulierten Intermediaten zu den ersten strukturell charakterisierten Komplexen

Cited by 10 publications

References 63 publications

Oxidative Addition of Halogens to Homoleptic Perfluoromethyl or Perfluorophenyl Derivatives of Platinum(II): A Comparative Study

Oxidative Addition of Halogens to Homoleptic Perfluoromethyl or Perfluorophenyl Derivatives of Platinum(II): A Comparative Study

Novel T‐Shaped 14‐Electron Platinum(II) Complexes Stabilized by One Agostic Interaction

A Pseudotetrahedral, High‐Oxidation‐State Organonickel Compound: Synthesis and Structure of Bromotris(1‐norbornyl)nickel(IV)

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