Bet You Missed It: What Do Spies and Dinosaurs Have in Common?

The tetranuclear [{Pt­(CNC)­(tht)}₃Tl]­(PF₆) (tht = tetrahydrothiophene; SC₄H₈; CNC = <i>C</i>,<i>N</i>,<i>C</i>-2,6-NC₅H₃(C₆H₄-2)₂; <b>2</b>) cluster has been prepared by the reaction of [Pt­(CNC)­(tht)] (<b>1</b>) and TlPF₆ (molar ratio 3:1) and structurally characterized. The Tl^I atom is bonded to three Pt^II centers bearing a perfect trigonal coordination. The Pt^II–Tl^I bonds are unsupported by any bridging ligand and are the shortest of this kind reported so far [2.9086(5) Å]. These intermetallic bonds persist in a CD₂Cl₂ solution, as shown by the ¹⁹⁵Pt­{¹H} NMR spectrum of <b>2</b> at 193 K, in which a Pt–Tl coupling of 8.9 kHz is observed

Synthesis, Characterization, And Computational Study of Complexes Containing Pt···H Hydrogen Bonding Interactions

Complexes [Pt­(C₆F₅)­(bzq)­L] (bzq = 7,8-benzoquinolinate; L = 8-hydroxyquinoline, hqH (<b>1</b>); 2-methyl-8-hydroxyquinoline, hqH′ (<b>2</b>)) have been prepared by replacing the labile acetone ligand in the starting material [Pt­(C₆F₅)­(bzq)­(Me₂CO)]. The ¹H NMR spectra of <b>1</b> and <b>2</b> show that the signals attributable to the hydroxyl proton of the hqH or hqH′ ligands are displaced downfield 2.64 ppm for <b>1</b> and 2.74 ppm for <b>2</b> with respect to the respective free ligands. Moreover, in both complexes the signals present platinum satellites with <i>J</i>(Pt,H) coupling constant of 67.0 Hz for <b>1</b> and 80.6 Hz for <b>2</b>. All these features are indicative of the existence of Pt···H–O hydrogen bonds in solution for these complexes. The structures of complexes <b>1</b> and <b>2</b> have been established by an X-ray diffraction study and allow us to confirm the existence of these interactions in the solid state too. Thus, in both cases the hydroxyl hydrogen atom is pointing toward the metal center, and the measured geometric parameters involving this hydrogen are Pt–H = 2.09(4) Å, O–H = 0.94(4) Å, Pt–H–O 162(4)°, for <b>1</b>, and Pt–H = 2.10(4) Å, O–H = 0.91(4) Å, Pt–H–O 162(4)°, for <b>2</b>, all of which are fully compatible with a hydrogen bond system. Complexes <b>1</b> and <b>2</b> and the analogues [Pt­(C₆F₅)₃(hqH)]⁻ (<b>A</b>) and [Pt­(C₆F₅)₃(hqH′)]⁻ (<b>B</b>), prepared some time ago in our laboratory and also showing Pt···H–O hydrogen bonds, have been the object of theoretical calculations to obtain better insight into the Pt···H interactions. Their density functional theory (DFT) calculated structures show excellent agreement with the X-ray determined ones (<b>1</b>, <b>2</b>, and <b>B</b>). Topological analyses of the electron density function (ρ­(<b>r</b>)) have been performed on the four complexes according to Bader’s <i>Atoms In Molecules</i> theory. These analyses reveal a bond path that relates the platinum atom and the hydroxyl hydrogen atom, as well as the corresponding bond critical points. The values of the Laplacian ∇²ρ­(<b>r</b>) and local energy density <i>H</i>(<b>r</b>) indicate that these are closed shell, electrostatic interactions, but with <i>partial covalence</i>. The deprotonation of the OH fragment in <b>1</b> and <b>2</b> with BuLi leads to the formation of the unexpected trinuclear complexes (NBu₄)­[Li­{Pt­(C₆F₅)­(bzq)­(L)}₂] (L = hq (<b>3</b>), hq′ (<b>4</b>)). The X-ray structures of these have shown a change in the coordination of the deprotonated hq and hq′, which are now bonded to the Pt atoms through their O atoms, and which are bridging the Pt and Li metal atoms

New Dicyano Cyclometalated Compounds Containing Pd(II)–Tl(I) Bonds as Building Blocks in 2D Extended Structures: Synthesis, Structure, and Luminescence Studies

New mixed metal complexes [PdTl­(C^∧N)­(CN)₂] [C^∧N = 7,8-benzoquinolinate (bzq, <b>3</b>); 2-phenylpyridinate (ppy, <b>4</b>)] have been synthesized by reaction of their corresponding precursors (NBu₄)­[Pd­(C^∧N)­(CN)₂] [C^∧N = bzq (<b>1</b>), ppy (<b>2</b>)] with TlPF₆. Compounds <b>3</b> and <b>4</b> were studied by X-ray diffraction, showing the not-so-common Pd^II–Tl^I bonds. Both crystal structures exhibit 2-D extended networks fashioned by organometallic “PdTl­(C^∧N)­(CN)₂” units, each one containing a donor–acceptor Pd­(II)–Tl­(I) bond, which are connected through additional Tl···NC contacts and weak Tl···π (bzq) contacts in the case of <b>3</b>. Solid state emissions are red-shifted compared with those of the precursors and have been assigned to metal–metal′-to-ligand charge transfer (MM′LCT [d/s σ*­(Pd,Tl) → π*­(C^∧N)]) mixed with some intraligand (³IL­[π­(C^∧N) → π*­(C^∧N)]) character. In diluted solution either at room temperature or 77 K, the Pd–Tl bond is no longer retained as confirmed by mass spectrometry, NMR, and UV–vis spectroscopic techniques

N‑Assisted C_Ph–H Activation in 3,8-Dinitro-6-phenylphenanthridine. New C,N-Cyclometalated Compounds of Platinum(II): Synthesis, Structure, and Luminescence Studies

The activation of a C_Ph–H bond in the phenyl ring of 3,8-dinitro-6-phenylphenanthridine (HC^∧N) can be achieved by refluxing the intermediate [PtCl­(η³-2-Me-C₃H₄)­(HC^∧N-κ<i>N</i>)] (<b>1</b>) (η³-2-Me-C₃H₄ = η³-2-methylallyl) in 2-methoxyethanol to render the new cyclometalated complex [{Pt­(μ-Cl)­(C^∧N)}₂] (<b>2</b>). The cleavage of the bridging system in <b>2</b> by the neutral ligands L rendered the mononuclear complexes [PtCl­(C^∧N)­L] (L = tht <b>3</b>, PPh₃ <b>4</b>, CN^<i>t</i>Bu <b>5</b>) with the geometry (<i>trans</i> C, Cl).The air- and temperature-stable cationic compound [Pt­(C^∧N)­(CNXyl)₂]­ClO₄ (<b>6</b>) could be prepared from <b>2</b> by addition of CNXyl (1:4 molar ratio) after the Cl abstraction with AgClO₄. Compound [Pt­(C^∧N-κ<i>C</i>)­(tht)₃]­ClO₄ (<b>7</b>) was prepared similarly to <b>6</b> but using a significant excess of tht, which produces the N-dissociation of the C^∧N ligand. The photophysical properties of compounds <b>3</b>–<b>6</b> have been studied with the help of time-dependent density functional theory (TD-DFT) calculations. In 2-Me-THF at low temperature (77 K) the green emission of the HC^∧N ligand turns to red phosphorescence in compounds <b>3</b>–<b>6</b>, which was assigned to a mixed metal-to-ligand charge transfer/intraligand/ligand-to-ligand charge transfer [³MLCT/³IL/³L′LCT] excited state. In the solid state at low temperature (77 K) the emissive behaviors are quite similar to that observed in glassy solutions with some contribution of excimeric π–π* emissions in the neutral chloro derivatives. Compounds <b>4</b>–<b>6</b> are also emissive in the solid state at room temperature with photoluminescence quantum yields (Φ) between 0.032 and 0.05

Pt₂Tl Building Blocks for Two-Dimensional Extended Solids: Synthesis, Crystal Structures, and Luminescence

The β-diketonate compounds of Pt­(II), [Pt­(R-C^C*)­(acac)] (acacH = acetylacetone, R-CH^C* = 1-(4-cyanophenyl)-3-methyl-1<i>H</i>-imidazol-2-ylidene (NC–CH^C*) <b>1A</b>, 1-(4-(ethoxycarbonyl)­phenyl)-3-methyl-1<i>H</i>-imidazol-2-ylidene (CO₂Et-CH^C*) <b>1B</b>, 1-(3,5-dichlorophenyl)-3-methyl-1<i>H</i>-imidazol-2-ylidene (Cl-CH^C*) <b>1C</b>) containing cyclometalated N-heterocyclic carbenes were synthesized from compounds [{Pt­(μ-Cl)­(R-C^C*)}₂] (R = CN <b>A</b>, CO₂Et <b>B</b>, Cl <b>C</b>). Compound <b>C</b> was prepared for the first time following a step-by-step protocol used to synthesize <b>A</b> and <b>B</b>. The X-ray structures of complexes <b>1B</b> and <b>1C</b> show that only in <b>1B</b> the molecules stack in pairs through intermolecular Pt···Pt (3.370 Å) and π–π (∼3.43 Å) interactions between the NHC ligand and the acac. The reaction of compounds <b>1A</b>–<b>1C</b> with TlPF₆ (2:1 molar ratio) leads to the clusters [{Pt­(R-C^C*)­(acac)}₂Tl]⁺ (R = CN <b>2A</b>, CO₂Et <b>2B</b>, Cl <b>2C</b>), which exhibit a “Pt₂Tl” sandwich structure, where two slightly distorted square planar “Pt­(R-C^C*)­(acac)” subunits are bonded to a Tl­(I) center through donor–acceptor Pt–Tl bonds. Compounds <b>2A</b> and <b>2B</b> show an extended two-dimensional lattice in the solid state through intermolecular Pt··Pt and Tl–E (E = N, O) interactions; meanwhile <b>2C</b> forms discrete molecules without any kind of intermolecular interaction among them. The effects of the R substituent and the Pt–Tl interactions on the crystal structures and the photophysical properties have been investigated

Solvent-Driven P–S vs P–C Bond Formation from a Diplatinum(III) Complex and Sulfur-Based Anions

The outcome of the reaction of the Pt­(III),Pt­(III) complex [(C₆F₅)₂Pt^III(μ-PPh₂)₂Pt^III(C₆F₅)₂]­(<i>Pt–Pt</i>) (<b>1</b>) with the S-based anions thiophenoxide (PhS^–), ethyl xanthogenate (EtOCS₂^–), 2-mercaptopyrimidinate (pymS^–), and 2-mercaptopyridinate (pyS^–) was found to be dependent on the reaction solvent. The reactions carried out in acetone led to the formation of [NⁿBu₄]­[(R_F)₂Pt^II(μ-PhS-PPh₂)­(μ-PPh₂)­Pt^II(R_F)₂] (<b>2</b>), [NⁿBu₄]­[(R_F)₂Pt^II(μ-EtOCS₂-PPh₂)­(μ-PPh₂)­Pt^II(R_F)₂] (<b>3</b>), [NⁿBu₄]­[(R_F)₂Pt^II(μ-pymS-PPh₂)­(μ-PPh₂)­Pt^II(R_F)₂] (<b>4</b>), and [NⁿBu₄]­[(R_F)₂Pt^II(μ-pyS–PPh₂)­(μ-PPh₂)­Pt^II(R_F)₂] (<b>5</b>), respectively (R_F = C₆F₅). Complexes <b>2</b>–<b>5</b> display new Ph₂P­(SL) ligands exhibiting a κ²-<i>P</i>,<i>S</i> bridging coordination mode, which is derived from a reductive elimination of a PPh₂ group and the S-based anion. Carrying out the reaction in dichloromethane afforded, in the cases of EtOCS₂^– and pymS^–, the monobridged complexes [NⁿBu₄]­[(PPh₂R_F)­(R_F)₂Pt^II(μ-PPh₂)­Pt^II(EtOCS₂)­(R_F)] (<b>6</b>) and [NⁿBu₄]­[(PPh₂R_F)­(R_F)₂Pt^II(μ-PPh₂)­Pt^II(pymS)­(R_F)] (<b>7</b>), respectively, which are derived from reductive elimination of a PPh₂ group with a pentafluorophenyl ring. The reaction of <b>1</b> with EtOCS₂K in acetonitrile yielded a mixture of <b>3</b> and <b>6</b> as a consequence of the concurrence of two processes: (a) the formation of <b>3</b> by a reaction that parallels the formation of <b>3</b> by <b>1</b> plus EtOCS₂K in acetone and (b) the transformation of <b>1</b> into the neutral complex [(PPh₂R_F)­(CH₃CN)­(R_F)­Pt^II(μ-PPh₂)­Pt^II(R_F)₂(CH₃CN)] (<b>8</b>), which, in turn, reacts with EtOCS₂K to give <b>6</b>. The <b>1</b> to <b>8</b> transformation was found to be fully reversible. In fact, dissolving <b>8</b> in acetone or dichloromethane afforded pure <b>1</b> after solvent evaporation or crystallization with <i>n</i>-hexane. The XRD structures of <b>2</b>–<b>4</b> and <b>6</b>–<b>8</b> were determined, and the behavior in solution of the new complexes is discussed

An Extended Chain and Trinuclear Complexes Based on Pt(II)–M (M = Tl(I), Pb(II)) Bonds: Contrasting Photophysical Behavior

The syntheses and structural characterizations of a Pt–Tl chain [{Pt­(bzq)­(C₆F₅)₂}­Tl­(Me₂CO)]_<i>n</i> <b>1</b> and two trinuclear Pt₂M clusters (NBu₄)­[{Pt­(bzq)­(C₆F₅)₂}₂Tl] <b>2</b> and [{Pt­(bzq)­(C₆F₅)₂}₂Pb] <b>3</b> (bzq = 7,8-benzoquinolinyl), stabilized by donor–acceptor Pt → M bonds, are reported. The one-dimensional heterometallic chain <b>1</b> is formed by alternate “Pt­(bzq)­(C₆F₅)₂” and “Tl­(Me₂CO)” fragments, with Pt–Tl bond separations in the range of 2.961(1)–3.067(1) Å. The isoelectronic trinuclear complexes <b>2</b> (which crystallizes in three forms, namely, <b>2a</b>, <b>2b</b>, and <b>2c</b>) and <b>3</b> present a sandwich structure in which the Tl­(I) or Pb­(II) is located between two “Pt­(bzq)­(C₆F₅)₂” subunits. NMR studies suggest equilibria in solution implying cleavage and reformation of Pt–M bonds. The lowest-lying absorption band in the UV–vis spectra in CH₂Cl₂ and tetrahydrofuran (THF) of <b>1</b>, associated with ¹MLCT/¹L′LCT ¹[5d_π(Pt) → π*­(bzq)]/¹[(C₆F₅) → bzq], displays a blue shift in relation to the precursor, suggesting the cleavage of the chain maintaining bimetallic Pt–Tl fragments in solution, also supported by NMR spectroscopy. In <b>2</b> and <b>3</b>, it shows a blue shift in THF and a red shift in CH₂Cl₂, supporting a more extensive cleavage of the Pt–M bonds in THF solutions than in CH₂Cl₂, where the trinuclear entities are predominant. The Pt–Tl chain <b>1</b> displays in solid state a bright orange-red emission ascribed to ³MM′CT (M′ = Tl). It exhibits remarkable and fast reversible vapochromic and vapoluminescent response to donor vapors (THF and Et₂O), related to the coordination/decoordination of the guest molecule to the Tl­(I) ion, and mechanochromic behavior, associated with the shortening of the intermetallic Pt–Tl separations in the chain induced by grinding. In frozen solutions (THF, acetone, and CH₂Cl₂) <b>1</b> shows interesting luminescence thermochromism with emissions strongly dependent on the solvent, concentration, and excitation wavelengths. The Pt₂Tl complex <b>2</b> shows an emission close to <b>1</b>, ascribed to charge transfer from the platinum fragment to the thallium [³(L+L′)­MM′CT]. <b>2</b> also shows vapoluminescent behavior in the presence of vapors of Me₂CO, THF, and Et₂O, although smaller and slower than those of <b>1</b>. The trinuclear neutral complex Pt₂Pb <b>3</b> displays a blue-shift emission band, tentatively assigned to admixture of ³MM′CT ³[Pt­(d) → Pb­(sp)] with some metal-mediated intraligand (³ππ/³ILCT) contribution. In contrast to <b>1</b> and <b>2</b>, <b>3</b> does not show vapoluminescent behavior

Synthesis and Characterization of the Double Salts [Pt(bzq)(CNR)₂][Pt(bzq)(CN)₂] with Significant Pt···Pt and π···π Interactions. Mechanistic Insights into the Ligand Exchange Process from Joint Experimental and DFT Study

Double complex salts (DCSs) of stoichiometry [Pt­(bzq)­(CNR)₂]­[Pt­(bzq)­(CN)₂] (bzq = 7,8-benzoquinolinate; R = <i>tert</i>-butyl (<b>1</b>), 2,6-dimethylphenyl (<b>2</b>), 2-naphtyl (<b>3</b>)) have been prepared by a metathesis reaction between [Pt­(bzq)­(CNR)₂]­ClO₄ and [K­(H₂O)]­[Pt­(bzq)­(CN)₂] in a 1:1 molar ratio under controlled temperature conditions (range: −10 to 0 °C). Compounds <b>1</b>–<b>3</b> have been isolated as air-stable and strongly colored solids [purple (<b>1</b>), orange (<b>2</b>), red-purple (<b>3</b>)]. The X-ray structure of <b>2</b> shows that it consists of ionic pairs in which the cationic and anionic square-planar Pt­(II) complexes are almost parallel to each other and are connected by Pt–Pt (3.1557(4) Å) and π···π (3.41–3.79 Å) interactions. Energy decomposition analysis calculations on DCSs <b>1</b>–<b>3</b> showed relatively strong ionic-pair interactions (estimated interaction energies of −99.1, −110.0, and −108.6 kcal/mol), which are dominated by electrostatic interactions with small contributions from dispersion (π···π) and covalent (Pt···Pt) bonding interactions involving the 5d and 6p atomic orbitals of the Pt centers. Compounds <b>1</b>–<b>3</b> undergo a thermal (165 °C, 24 h) irreversible ligand rearrangement process in the solid state and also in solution at temperatures above 0 °C to give the neutral complexes [Pt­(bzq)­(CN)­(CNR)] as a mixture of two possible isomers (SP-4-2 and SP-4-3). The mechanism of this process has been thoroughly explored by combined NMR and DFT studies. DFT calculations on <b>1</b>–<b>3</b> show that the existing Pt···Pt interactions block the associative attack of the Pt­(II) centers by the coordinated cyanide and/or isocyanide ligands. Moreover, they support a significant transfer of electron density from the anionic to the cationic component (0.20–0.32 |e|), which renders the isocyanide ligand dissociation more feasible than that in the “free-standing” cationic [Pt­(bzq)­(CNR)₂]⁺ components as well as the dissociation of the CN^– in <i>trans</i> position to the C_bzq in the anionic [Pt­(bzq)­(CN)₂]⁻ component. Therefore, the first step in the ligand rearrangement pathway is the dissociation of the isocyanide in <i>trans</i> position to the C_bzq, yielding the [(RNC)­(bzq)­(μ₂-η¹,η¹-CN)­Pt···Pt­(bzq)­(CN)] intermediates. The rate-limiting step corresponds to the transformation of these intermediates to the neutral [Pt­(bzq)­(CN)­(CNR)] complexes following a synchronous mechanism involving rupture of the Pt–Pt and formation of the Pt–CN bonds through transition states formulated as [(RNC)­(bzq)­Pt­(μ₂-η¹,η¹-CN)­Pt­(bzq)­(CN)]

Synthesis and Characterization of the Double Salts [Pt(bzq)(CNR)₂][Pt(bzq)(CN)₂] with Significant Pt···Pt and π···π Interactions. Mechanistic Insights into the Ligand Exchange Process from Joint Experimental and DFT Study

Double complex salts (DCSs) of stoichiometry [Pt­(bzq)­(CNR)₂]­[Pt­(bzq)­(CN)₂] (bzq = 7,8-benzoquinolinate; R = <i>tert</i>-butyl (<b>1</b>), 2,6-dimethylphenyl (<b>2</b>), 2-naphtyl (<b>3</b>)) have been prepared by a metathesis reaction between [Pt­(bzq)­(CNR)₂]­ClO₄ and [K­(H₂O)]­[Pt­(bzq)­(CN)₂] in a 1:1 molar ratio under controlled temperature conditions (range: −10 to 0 °C). Compounds <b>1</b>–<b>3</b> have been isolated as air-stable and strongly colored solids [purple (<b>1</b>), orange (<b>2</b>), red-purple (<b>3</b>)]. The X-ray structure of <b>2</b> shows that it consists of ionic pairs in which the cationic and anionic square-planar Pt­(II) complexes are almost parallel to each other and are connected by Pt–Pt (3.1557(4) Å) and π···π (3.41–3.79 Å) interactions. Energy decomposition analysis calculations on DCSs <b>1</b>–<b>3</b> showed relatively strong ionic-pair interactions (estimated interaction energies of −99.1, −110.0, and −108.6 kcal/mol), which are dominated by electrostatic interactions with small contributions from dispersion (π···π) and covalent (Pt···Pt) bonding interactions involving the 5d and 6p atomic orbitals of the Pt centers. Compounds <b>1</b>–<b>3</b> undergo a thermal (165 °C, 24 h) irreversible ligand rearrangement process in the solid state and also in solution at temperatures above 0 °C to give the neutral complexes [Pt­(bzq)­(CN)­(CNR)] as a mixture of two possible isomers (SP-4-2 and SP-4-3). The mechanism of this process has been thoroughly explored by combined NMR and DFT studies. DFT calculations on <b>1</b>–<b>3</b> show that the existing Pt···Pt interactions block the associative attack of the Pt­(II) centers by the coordinated cyanide and/or isocyanide ligands. Moreover, they support a significant transfer of electron density from the anionic to the cationic component (0.20–0.32 |e|), which renders the isocyanide ligand dissociation more feasible than that in the “free-standing” cationic [Pt­(bzq)­(CNR)₂]⁺ components as well as the dissociation of the CN^– in <i>trans</i> position to the C_bzq in the anionic [Pt­(bzq)­(CN)₂]⁻ component. Therefore, the first step in the ligand rearrangement pathway is the dissociation of the isocyanide in <i>trans</i> position to the C_bzq, yielding the [(RNC)­(bzq)­(μ₂-η¹,η¹-CN)­Pt···Pt­(bzq)­(CN)] intermediates. The rate-limiting step corresponds to the transformation of these intermediates to the neutral [Pt­(bzq)­(CN)­(CNR)] complexes following a synchronous mechanism involving rupture of the Pt–Pt and formation of the Pt–CN bonds through transition states formulated as [(RNC)­(bzq)­Pt­(μ₂-η¹,η¹-CN)­Pt­(bzq)­(CN)]

Synthesis and Reactivity of the Unsaturated Trinuclear Phosphanido Complex [(C₆F₅)₂Pt(μ-PPh₂)₂Pt(μ-PPh₂)₂Pt(PPh₃)]

The reaction of [NBu₄]­[(C₆F₅)₂Pt­(μ-PPh₂)₂Pt­(μ-PPh₂)₂Pt­(<i>O</i>,<i>O</i>-acac)] (48 VEC) with [HPPh₃]­[ClO₄] gives the 46 VEC unsaturated [(C₆F₅)₂Pt¹(μ-PPh₂)₂Pt²(μ-PPh₂)₂Pt³(PPh₃)]­(Pt²–Pt³) (<b>1</b>), a trinuclear compound endowed with a Pt–Pt bond. This compound displays amphiphilic behavior and reacts easily with nucleophiles L, yielding the saturated complexes [(C₆F₅)₂Pt^II(μ-PPh₂)₂Pt^II(μ-PPh₂)₂Pt^II(PPh₃)­L] [L = PPh₃ (<b>2</b>), py (<b>3</b>)]. The reaction with the electrophile [Ag­(OClO₃)­PPh₃] affords the adduct <b>1</b>·AgPPh₃, which evolves, even at low temperature, to a mixture in which [(C₆F₅)₂Pt^III(μ-PPh₂)₂Pt^III(μ-PPh₂)₂Pt^II(PPh₃)₂]²⁺(Pt^III–Pt^III) and <b>2</b> (plus silver metal) are present. The nucleophilic nature of <b>1</b> is also demonstrated through its reaction with <i>cis</i>-[Pt­(C₆F₅)₂(THF)₂], which results in the formation of [Pt₄(μ-PPh₂)₄(C₆F₅)₄(PPh₃)] (<b>4</b>). The structure and NMR features indicate that <b>1</b> can be better considered as a Pt^II–Pt^III–Pt^I complex instead of a Pt^II–Pt^II–Pt^II derivative. Theoretical calculations (density functional theory) on similar model compounds are in agreement with the assigned oxidation states of the metal centers. The strong intermetallic interactions resulting in a Pt²–Pt³ metal–metal bond and the respective bonding mechanism were verified by employing a multitude of computational techniques (natural bond order analysis, the Laplacian of the electron density, and localized orbital locator profiles)