Crystal and Molecular Structure of a New Linear Chain Compound: Bis(diphenylglyoximato)platinum(III)perchlorate

Several complexes of “PtL2” composition containing two cyanoxime anions – 2-oximino-2-cyano-N-piperidineacetamide (PiPCO−) and 2-oximino-2-cyano-N-morpholylacetamide (MCO−) have been obtained and characterized both in solutions and in solid state. Complexes exist as two distinct polymorphs: monomeric yellow complexes, and dark-green [PtL2]n 1D polymers, while for the MCO− anion a red, solvent containing dimeric [Pt(MCO)2xDMSO]2 complex also has been isolated. The interconversion of polymorphs was investigated. The monomeric PtL2 units are arranged into the anisotropic extended solid [PtL2]n polymers with the help of Pt—Pt metallophilic interactions. Crystal structures of monomeric PtL2 (L= PiPCO−, MCO−) and red dimeric [Pt(MCO)2xDMSO]2 complexes were determined and revealed the cis-arrangement of cyanoxime anions. The Pt-Pt distance in the “head-to-tail” red dimer was found to be 3.133 Å. The structure of polymeric [Pt(PiPCO)2]n compound was elucidated using the EXAFS method and evidenced the formation of the Pt-wire with ~3.15 Å intermetallic separations. The EPR spectra of both 1D polymers at variable temperatures indicate the absence of Pt(III) species. Both pure dark-green [PtL2]n polymers showed considerable room temperature electrical conductivity of 20–30 S/cm, which evidences the formation of mixed valence Pt(II)/Pt(IV) system. We discovered that these 1D polymeric [PtL2]n complexes show an intense NIR fluorescence beyond 1000 nm, while yellow monomeric PtL2 complexes are not emissive at all. The room temperature excitation spectra of 1D polymeric [PtL2]n complexes demonstrated their strong emission beyond 1000 nm regardless of the used excitation wavelength between 350 and 800 nm, which is typical of systems with delocalized charge carriers. For the first time the formation of mixed valence “metal wire” assembled by metallophilic interactions is directly linked both with an intense fluorescence in the NIR region of spectrum and the electrical conductivity. The effect of concentration of [PtL2]n complexes dispersed in the dielectric salt matrix on the photoluminescence wavelength and intensity was investigated. Both polymers show a remarkably high for this region of spectrum quantum yield reaching ~2%. Variable temperature emission of polymeric [PtL2]n in the −190 - +60°C range was studied as well.

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“…The same situation was well documented for classic mixed valence MX and KCP/POCP 1D solids (ESI 1) in the past. 5, 10, 13, 66 …”

Section: Resultsmentioning

confidence: 99%

Shortwave infrared luminescent Pt-nanowires: a mechanistic study of emission in solution and in the solid state

et al. 2017

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“…Despite the traditional coordination mode of the oxime ligands, these two complexes are the first example of structurally characterized derivatives of platinum(IV) with vic -dioximes. Previously only complexes of both platinum(II) − and platinum(III) , that contain dioximes were subject of crystallographic studies.…”

Section: Resultsmentioning

confidence: 99%

Iminoacylation. 3. Formation of Platinum(IV)-Based Metallaligands Due to Facile One-End Addition of vic-Dioximes to Coordinated Organonitriles^1-3

et al. 2000

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The reaction of vic-dioximes with the organonitrile platinum(IV) complexes trans-[PtCl4(RCN)2] (R = Me, CH2Ph, Ph, vic-dioxime = dimethylglyoxime; R = Me, vic-dioxime = cyclohexa-, cyclohepta-, and cyclooctanedione dioximes) proceeds rapidly under relatively mild conditions and affords products of one-end addition of the dioximes to the nitrile carbon, i.e. [PtC4(NH=C(R)ON=[spacer]=NOH)2] (1-6) (R = Me, CH2Ph, Ph, spacer = C(Me)C-(Me) for dimethylglyoxime; R = Me, spacer = C[C4H8]C, C[C5H10]C, C[C6H12]C for the other dioximes), giving a novel type of metallaligand. All addition compounds were characterized by elemental analyses (C, H, N, C1, Pt), FAB mass spectrometry, and IR and 1H, 13C[1H], and 195Pt NMR spectroscopy. X-ray structure determination of the dimethylformamide bis-solvate [PtCl4(NH=C(Me)ON=C(Me)C(Me)=NOH)2] x 2DMF (la) disclosed its overall trans geometry with the dimethylglyoxime part in anti configuration and the amidine one-end (rather than N,N-bidentate) coordination mode of the N-donor ligands. When a mixture of cis- and trans-[PtC4(MeCN)2] in MeCN was treated with dimethylglyoxime, the formation of, correspondingly, cis- and trans-[PtCl4(NH=C(Me)ON=C(Me)C(Me)=NOH)2] (1) was observed and cis-to-trans isomerization in DMSO-d6 solution was monitored by 1H, 2D [1H,15N] HMQC, and 195Pt NMR spectroscopies. Although performed ab initio calculations give evidence that the trans geometry is the favorable one for the iminoacylated species [PtCl4-(ligand)2], the platinum(IV) complex [PtCl4(NH=C(Me)ON=C[C4Hs]C=NOH)2] (4) was isolated exclusively in cis configuration with the two metallaligand "arms" held together by intramolecular hydrogen bonding between the two peripheral OH groups, as it was proved by single-crystal X-ray diffractometry. The classic substitution products, e.g. [PtC12(N,N-dioximato)2] (12-15), are formed in the addition reaction as only byproducts in minor yield; two of them, [PtCl2(C7H11N2O2)2] (14) and [PtCl2(C8H13N2O2)2] (15), were structurally characterized. Complexes (12-15) were also prepared by reaction of the vic-dioximes with [PtCl4L(Me2SO)] (L = Me2SO, MeCN), but monoximes (Me2C=NOH, [C4H8]C=NOH, [C5H10]C=NOH, PhC(H)=NOH, (OH)C6H4C(H)= NOH) react differently adding to [PtCl4(MeCN)(Me2SO)] to give the corresponding iminoacylated products [PtCl4(NH=C(Me)ON=CRR')(Me2SO)](7-11).

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“…Monomeric Pt III has an unpaired electron and only a few complexes of this type have been reported 5a,b [Pt(diphenylgliossimato) 2 ] + ,5c [Pt(1,8-diamino-3,6,10,13,16,19-hexaazabicyclo[6,6,6]icosane)] 3+ ,5d and [Pt(1,4,7-trithiacyclononane) 2 ] 3+ 5e…”

Section: Introductionmentioning

confidence: 99%

Synthesis and X-ray Structural Characterization of Two Unbridged Diplatinum(III) Compounds: cis- and trans-Bis[bis(1-imino-1-methoxyethane)trichloroplatinum(III)]. Transient Species in the Oxidation of Platinum(II) to Platinum(IV)

et al. 1997

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Unbridged PtIII dimers, cis- and trans-[PtCl3L2]2 (L = (E)-HNC(OMe)Me, cis- 2 and trans-2), are formed, as transient species, in the oxidation with excess chlorine of the PtII compounds cis- and trans-[PtCl2L2] (cis- 1 and trans-1) to the corresponding PtIV species, cis- and trans-[PtCl4L2] (cis- 3 and trans-3). Complexes cis- 2 and trans-2 are rather stable at low temperature (<0 and −20 °C for cis- 2 and trans-2, respectively), while at higher temperature (20 °C) they readily oxidize to PtIV (τ1/2 = 80 and 5 min for cis- 2 and trans-2, respectively). The structures of the PtIII species have been solved by single-crystal X-ray diffraction. The compounds are neutral dimers composed of two square-planar PtCl2L2 units perpendicularly connected by a Pt−Pt bond and capped by axially coordinated chloride ligands. Bond distances and angles within the equatorial PtCl2L2 units are normal. The axial Pt−Cl bond lengths are ca. 0.14 Å longer than the equatorial ones, indicating a strong trans influence of the intermetallic bond. The intermetallic bond distances are typical of either unbridged or pyrophosphite four-bridged PtIII dimers, while they are much longer than those found in other PtIII complexes with either two (>0.10 Å) or four bridging ligands (>0.20 Å). In cis-2, the iminoether ligands are in equivalent pairs, and a 90° rotation of one platinum subunit with respect to the other about the Pt−Pt vector interchanges the ligand positions and converts the complex into its enantiomeric form. Both enantiomers are found in the crystal and in solution, where a ΔG* of 16.9 ± 0.2 kcal mol-1 was calculated for the interconversion process (1H NMR). The formation of intermediate PtIII dimers appears to be a relatively common, although overlooked, feature of platinum chemistry. The oxidation of PtII to PtIV requires the removal of two electrons by the oxidant (an acid), assisted by a ligand (a base) entering the coordination sphere from the opposite side. A second PtII unit can act as a base contributing two d z 2 electrons and binding face-to-face from the axial direction. The resulting dimer completes the coordination sphere of the adjoined platinum unit by binding an extra ligand.

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Crystal and Molecular Structure of a New Linear Chain Compound: Bis(diphenylglyoximato)platinum(III)perchlorate

Cited by 14 publications

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Shortwave infrared luminescent Pt-nanowires: a mechanistic study of emission in solution and in the solid state

Shortwave infrared luminescent Pt-nanowires: a mechanistic study of emission in solution and in the solid state

Iminoacylation. 3. Formation of Platinum(IV)-Based Metallaligands Due to Facile One-End Addition of vic-Dioximes to Coordinated Organonitriles^1-3

Synthesis and X-ray Structural Characterization of Two Unbridged Diplatinum(III) Compounds: cis- and trans-Bis[bis(1-imino-1-methoxyethane)trichloroplatinum(III)]. Transient Species in the Oxidation of Platinum(II) to Platinum(IV)

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Crystal and Molecular Structure of a New Linear Chain Compound: Bis(diphenylglyoximato)platinum(III)perchlorate

Cited by 14 publications

References 0 publications

Shortwave infrared luminescent Pt-nanowires: a mechanistic study of emission in solution and in the solid state

Shortwave infrared luminescent Pt-nanowires: a mechanistic study of emission in solution and in the solid state

Iminoacylation. 3. Formation of Platinum(IV)-Based Metallaligands Due to Facile One-End Addition of vic-Dioximes to Coordinated Organonitriles1-3

Synthesis and X-ray Structural Characterization of Two Unbridged Diplatinum(III) Compounds: cis- and trans-Bis[bis(1-imino-1-methoxyethane)trichloroplatinum(III)]. Transient Species in the Oxidation of Platinum(II) to Platinum(IV)

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Iminoacylation. 3. Formation of Platinum(IV)-Based Metallaligands Due to Facile One-End Addition of vic-Dioximes to Coordinated Organonitriles^1-3