Synthesis of Pt(dpk)Cl₄ and the Reversible Hydration to Pt(dpk-O-OH)Cl₃·H-phenCl:  X-ray, Spectroscopic, and Electrochemical Characterization

Abstract

We report on the synthesis of a platinum(IV) compound containing a di-2-pyridyl ketone (dpk) ligand that is stable both in its anhydrous form [Pt(dpk)Cl(4)] (1) and in its hydrated form [Pt(dpk-O-OH)Cl(3)].H-phenCl (2). The crystal structure of the hydrated form shows that one of the hydroxide groups from the resulting gem-diol has undergone a cyclometalation/condensation reaction resulting in an oxygen atom directly coordinated to the Pt(IV) center and the formation of H-phenCl. We correlate our physical data with predictions made by molecular modeling, and we propose an explanation for the unusual activity found for this dpk ketone. Spectroscopic and solubility studies are presented here, as well. Electrochemical studies of 1 indicate that it undergoes a highly irreversible reduction at a potential of about -0.45 V vs Ag(+)/Ag in CH(3)CN and that the irreversibility is likely due to an EC mechanism, the nature of which is currently under further investigation. Another distinct redox pair, apparently reversible, appears at a potential of about -1.1 V vs Ag(+)/Ag.

The Effect of Monodentate Co-Ligands on the Properties of Pt(II) Complexes Bearing a Tridentate C^N*N-Luminophore

“…The irreversible reduction wave of [PtNO 2 (L)] at −2.430 V (located on the edge of the solvent's window) can be attributed to a nitrito-centered reduction, according to previous reports [69,70]. For [PtCO(L)], two smaller yet irreversible reduction peaks were observed at −1.260 V and −1.670 V. In the case of [PtCl 3 (L)], one irreversible wave was detected at −1.087 V, which can be assigned to the reduction of the Pt(IV) center [71,72].…”

The Effect of Monodentate Co-Ligands on the Properties of Pt(II) Complexes Bearing a Tridentate C^N*N-Luminophore

“…The irreversible reduction wave of [PtNO 2 (L)] at −2.430 V (located on the edge of the solvent's window) can be attributed to a nitrito-centered reduction, according to previous reports [69,70]. For [PtCO(L)], two smaller yet irreversible reduction peaks were observed at −1.260 V and −1.670 V. In the case of [PtCl 3 (L)], one irreversible wave was detected at −1.087 V, which can be assigned to the reduction of the Pt(IV) center [71,72].…”

Nucleophilic addition of water to 1-isoquinolinyl phenyl ketone. The synthesis, spectroscopic investigation, crystal and molecular structure and DFT calculations of [ReOBr2(iquinpk-OH)(PPh3)]

“…The elemental analysis of the complex is in good agreement with its postulated molecular formula [15]. The medium intensity band at 3410 cm À1 assignable to m(OH) vibrations and absence of the strong band in the region expected for m(C@O) vibrations confirms the monoanionic gem-diol form of iquinpk in the coordination sphere of the prepared complex [16]. The characteristic bands of the C@C and C@N stretching modes are observed in the range 1630-1550 cm À1 [21].…”

Hydridodimethylplatinum(IV) Complexes with Bis(pyridine) Ligands: Effect of Chelate Ring Size on Reactivity

“…We have independently studied the effect of increasing the chelate ring size by using the ligands di-2-pyridylamine (DPA) and di-2-pyridyl ketone (DPK). These both form six-membered chelate rings, and previous studies have shown that the ligands are similarly bowed rather than planar in their platinum complexes. − The electronic effects of the bridging NH group in DPA 18 or CO group in DPK 19,20 are different, thus making it possible to distinguish between geometrical and electronic effects on the reactivity of complexes [PtMe 2 (DPA)] ( 1 ) and [PtMe 2 (DPK)] ( 2 ) in comparison with [PtMe 2 (bipy)]. This article shows that the ligands DPA and DPK both give more stable hydridoplatinum(IV) complexes and easier H−D exchange reactions in comparison with 2,2‘-bipyridine ligands 1,4 and reports the first structure determination of a hydridomethylplatinum(IV) complex of the type [PtHXMe 2 (LL)], with an easily dissociated halide ligand.…”

The Effect of Monodentate Co-Ligands on the Properties of Pt(II) Complexes Bearing a Tridentate C^N*N-Luminophore

“…The irreversible reduction wave of [PtNO 2 (L)] at −2.430 V (located on the edge of the solvent's window) can be attributed to a nitrito-centered reduction, according to previous reports [69,70]. For [PtCO(L)], two smaller yet irreversible reduction peaks were observed at −1.260 V and −1.670 V. In the case of [PtCl 3 (L)], one irreversible wave was detected at −1.087 V, which can be assigned to the reduction of the Pt(IV) center [71,72].…”

Nucleophilic addition of water to 1-isoquinolinyl phenyl ketone. The synthesis, spectroscopic investigation, crystal and molecular structure and DFT calculations of [ReOBr2(iquinpk-OH)(PPh3)]

“…The elemental analysis of the complex is in good agreement with its postulated molecular formula [15]. The medium intensity band at 3410 cm À1 assignable to m(OH) vibrations and absence of the strong band in the region expected for m(C@O) vibrations confirms the monoanionic gem-diol form of iquinpk in the coordination sphere of the prepared complex [16]. The characteristic bands of the C@C and C@N stretching modes are observed in the range 1630-1550 cm À1 [21].…”

Hydridodimethylplatinum(IV) Complexes with Bis(pyridine) Ligands: Effect of Chelate Ring Size on Reactivity

“…We have independently studied the effect of increasing the chelate ring size by using the ligands di-2-pyridylamine (DPA) and di-2-pyridyl ketone (DPK). These both form six-membered chelate rings, and previous studies have shown that the ligands are similarly bowed rather than planar in their platinum complexes. − The electronic effects of the bridging NH group in DPA 18 or CO group in DPK 19,20 are different, thus making it possible to distinguish between geometrical and electronic effects on the reactivity of complexes [PtMe 2 (DPA)] ( 1 ) and [PtMe 2 (DPK)] ( 2 ) in comparison with [PtMe 2 (bipy)]. This article shows that the ligands DPA and DPK both give more stable hydridoplatinum(IV) complexes and easier H−D exchange reactions in comparison with 2,2‘-bipyridine ligands 1,4 and reports the first structure determination of a hydridomethylplatinum(IV) complex of the type [PtHXMe 2 (LL)], with an easily dissociated halide ligand.…”

The Effect of Monodentate Co-Ligands on the Properties of Pt(II) Complexes Bearing a Tridentate C^N*N-Luminophore

“…The irreversible reduction wave of [PtNO 2 (L)] at −2.430 V (located on the edge of the solvent's window) can be attributed to a nitrito-centered reduction, according to previous reports [69,70]. For [PtCO(L)], two smaller yet irreversible reduction peaks were observed at −1.260 V and −1.670 V. In the case of [PtCl 3 (L)], one irreversible wave was detected at −1.087 V, which can be assigned to the reduction of the Pt(IV) center [71,72].…”

Nucleophilic addition of water to 1-isoquinolinyl phenyl ketone. The synthesis, spectroscopic investigation, crystal and molecular structure and DFT calculations of [ReOBr2(iquinpk-OH)(PPh3)]

“…The elemental analysis of the complex is in good agreement with its postulated molecular formula [15]. The medium intensity band at 3410 cm À1 assignable to m(OH) vibrations and absence of the strong band in the region expected for m(C@O) vibrations confirms the monoanionic gem-diol form of iquinpk in the coordination sphere of the prepared complex [16]. The characteristic bands of the C@C and C@N stretching modes are observed in the range 1630-1550 cm À1 [21].…”

Hydridodimethylplatinum(IV) Complexes with Bis(pyridine) Ligands: Effect of Chelate Ring Size on Reactivity

“…We have independently studied the effect of increasing the chelate ring size by using the ligands di-2-pyridylamine (DPA) and di-2-pyridyl ketone (DPK). These both form six-membered chelate rings, and previous studies have shown that the ligands are similarly bowed rather than planar in their platinum complexes. − The electronic effects of the bridging NH group in DPA 18 or CO group in DPK 19,20 are different, thus making it possible to distinguish between geometrical and electronic effects on the reactivity of complexes [PtMe 2 (DPA)] ( 1 ) and [PtMe 2 (DPK)] ( 2 ) in comparison with [PtMe 2 (bipy)]. This article shows that the ligands DPA and DPK both give more stable hydridoplatinum(IV) complexes and easier H−D exchange reactions in comparison with 2,2‘-bipyridine ligands 1,4 and reports the first structure determination of a hydridomethylplatinum(IV) complex of the type [PtHXMe 2 (LL)], with an easily dissociated halide ligand.…”