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A structurally precise hydride‐containing Pt‐doped Cu‐rich nanocluster [PtH2Cu14{S2P(OiPr)2}6(CCPh)6] (1) has been synthesized. It consists of a bicapped icosahedral Cu14 cage that encapsulates a linear PtH2 unit. Upon the addition of two equivalents of CF3COOH to 1, two hydrido clusters are isolated. These clusters are [PtHCu11{S2P(OiPr)2}6(CCPh)4] (2), which is a vertex‐missing Cu11 cuboctahedron encaging a PtH moiety, and [PtH2Cu11{S2P(OiPr)2}6(CCPh)3] (3), a distorted 3,3,4,4,4‐pentacapped trigonal prismatic Cu11 cage enclosing a PtH2 unit. The electronic structure of 2, analyzed by Density Functional Theory, is a 2e superatom. The electrocatalytic activities of 1–3 for hydrogen evolution reaction (HER) were compared. Notably, Cluster 2 exhibited an exceptionally excellent HER activity within metal nanoclusters, with an onset potential of −0.03 V (at 10 mA cm−2), a Tafel slope of 39 mV dec−1, and consistent HER activity throughout 3000 cycles in 0.5 M H2SO4. Our study suggests that the accessible central Pt site plays a crucial role in the remarkable HER activity and may provide valuable insights for establishing correlations between catalyst structure and HER activity. [ABSTRACT FROM AUTHOR]

Carbonylmetallates [m]−, such as [MoCp(CO)3]−, [Mn(CO)5]−, [Co(CO)4]−, have long been successfully used in the preparation of hundreds of metal‐metal bonded carbonyl complexes and clusters, in particular of the heterometallic type. We focus here on situations where [m]− can be viewed as a terminal, doubly or even triply bridging metalloligand, developing metal‐metal interactions with one, two or three metal centers M, respectively. With metals M from the Groups 10–12, it is not straightforward or even impossible to rationalize the structure of the resulting clusters by applying the well‐known Wade‐Mingos rules. A very simple but global approach is presented to rationalize structures not obeying usual electron‐counting rules by considering the anionic building blocks [m]− as metalloligands behaving formally as potential 2‐, 4‐ or 6‐electron donors, similarly to what is typically encountered with for example halido ligands. Qualitative and theoretical arguments by using DFT calculations highlight similarities between seemingly unrelated metal complexes and clusters and also entail a predicting power with high synthetic potential. [ABSTRACT FROM AUTHOR]

Atomically precise thiolate-protected coinage metal nanoclusters and their alloys are far more numerous than their selenium congeners, the synthesis of which remains extremely challenging. Herein, we report the synthesis of a series of atomically defined dithiophosph(in)ate protected eight-electron superatomic palladium silver nanoalloys [PdAg20{S2PR2}12], 2a–c (where R = OiPr, a; OiBu, b; Ph, c) via ligand exchange and/or co-reduction methods. The ligand exchange reaction on [PdAg20{S2P(OnPr)2}12], 1, with [NH4{Se2PR2}12] (where R = OiPr, or OnPr) leads to the formation of [PdAg20{Se2P(OiPr)2}12] (3) and [PdAg20{Se2P(OnPr)2}12] (4), respectively. Solid state structures of 2a, 2b, 3 and 4 unravel different PdAg20 metal frameworks from their parent cluster, originating from the different distributions of the eight-capping silver(I) atoms around a Pd@Ag12 centered icosahedron with C2,D3,Th and Th symmetries, respectively. Surprisingly ambient temperature crystallization of the reaction product 3 obtained by the ligand exchange reaction on 1 has resulted in the co-crystallization of two isomers in the unit cell with overall T (3a) and C3 (3b) symmetries, respectively. To our knowledge, this is the first ever characterized isomeric pair among the selenolate-protected NCs. Density functional theory (DFT) studies further rationalize the preferred geometrical isomerism of the PdAg20 core. Atomically and structurally precise silver nanoclusters hold great potential for catalytic and optoelectronic applications. Here, the authors synthesize and characterize a series of atomically defined dithio- and diselenophosphate-protected eight-electron superatomic palladium-doped silver nanoclusters, including an unprecedented pair of selenolate-protected isomers. [ABSTRACT FROM AUTHOR]

The paramagnetic cluster [Cu43Al12](Cp*)12 was obtained from the reaction of [CuMes]5 and [AlCp*]4 (Cp*=η5‐C5Me5; Mes=mesityl). This all‐hydrocarbon ligand‐stabilized M55 magic atom‐number cluster features a Mackay‐type nested icosahedral structure. Its open‐shell 67‐electron superatom configuration is unique. Three unpaired electrons occupy weakly antibonding jellium states. The situation prefigures the formation of a conduction band, which is in line with the measured temperature‐independent magnetism. Steric protection by twelve Cp* ligands suppresses the intrinsic polyradicalar reactivity of the Cu43Al12 core. Superatomic: The reaction of [AlCp*]4 and [CuMes]5 yields the Mackay 55‐metal atom two‐shell icosahedral cluster [Cu43Al12](Cp*)12. The intermetalloid cluster has a unique 67‐electron open‐shell superatomic [Cu43Al12]12+ core, embedded inside an all‐hydrocarbon shell of twelve Cp*− ligands. Its electronic structure comprises a set of entangled HOMO und low‐lying LUMOs, prefiguring the formation of a conduction band. [ABSTRACT FROM AUTHOR]

Abstract: A templated galvanic exchange performed on [Ag20{Se2P(OiPr)2}12] of C3 symmetry with three equiv AuI yields a mixture of [Au1+xAg20−x{Se2P(OiPr)2}12]+ (x=0–2) from which [Au@Ag20{Se2P(OiPr)2}12]+ and [Au@Au2Ag18{Se2P(OiPr)2}12]+ are successfully characterized to have T and C1 symmetry, respectively. Crystal structural analyses combined with DFT calculations on the model compounds explicitly demonstrate that the central Ag0 of Ag20 being oxidized by AuI migrates to the protecting atomic shell as a new capping AgI, and both second and third Au dopants prefer occupying non‐adjacent icosahedron vertices. The differences in symmetry, T and C1, are manifested in the spatial orientation of their protecting atomic shell composed of eight capping Ag atoms as well as re‐construction upon the replacement of Ag atoms on the vertices of AuAg12 icosahedral core with second and third Au dopants. As a result, a unique pathway for substitutional‐doped clusters with increased nuclearity is proposed. [ABSTRACT FROM AUTHOR]

Herein we report a crystal structure of [Au0.5Ag0.5@Ag20{S2P(OiPr)2}12](PF6) [Cl@Ag8{S2P(OiPr)2}6](PF6) (1), which compositions were supported by positive-mode electrospray ionization mass spectrometry. The structural elucidation indicates that the encapsulated atom of an Ag13 the entered icosahedron can be replaced by a gold atom. Surprisingly, the capping Ag atoms on the surface of an icosahedron in 1 reveal a different arrangement from the previously reported [Ag21{S2P(OiPr)2}12](PF6) of C3 symmetry. Besides, the preference for the central silver atom being oxidized by Au(I) is rationalized by the DFT calculations on three different computed [AuAg20{S2PH2}12]+ models having C1, C3, and T symmetry, respectively. [ABSTRACT FROM AUTHOR]

DFT calculations were carried out at the BP86/LANL2DZ level of theory to probe the structures and relative stabilities of small and medium size ligated palladium clusters. Results show that optimized geometries satisfactorily mimic experimental structural data. Observed cluster electron counts generally deviate from the expected Wade-Mingos electron counts because of the presence of several non-conical T-shaped $${\hbox {ML}}_{3}$$ fragments in the clusters. These species are thermodynamically stable with substantial HOMO-LUMO gaps. [ABSTRACT FROM AUTHOR]

Two luminescent, monoanionic chalcogenide-centered nonanuclear silver clusters stabilized by dichalcogenophosphates were synthesized and fully characterized by various spectroscopies including multinuclear NMR and ESI-mass. Single crystal X-ray diffraction studies on both cluster anions, [Ag(S){SP(OEt)}], 1, and [Ag(Se){SeP(OEt)}], 2, reveal that the nine silver atoms form an extremely distorted tricapped trigonal prism, which has an encapsulating chalcogenide. The coordination geometry of the central chalcogenide appears to be monocapped trigonal prismatic, which was analyzed by DFT calculations. The origin of the yellow emission is assigned by TDDFT calculations to originate from a chalcogen (ligand + encapsulated) → silver charge transfer. [ABSTRACT FROM AUTHOR]

The first structurally characterized copper cluster with a Cu13 centered cuboctahedral arrangement, a model of the bulk copper fcc structure, was observed in [Cu13(S2CN nBu2)6(C≡CR)4](PF6) (R=C(O)OMe, C6H4F) nanoclusters. Four of the eight triangular faces of the cuboctahedron are capped by acetylide groups in μ3 fashion, and each of the six square faces is bridged by a dithiolate ligand in μ2,μ2 fashion, which leads to a truncated tetrahedron of twelve sulfur atoms. DFT calculations are fully consistent with the description of these Cu13 clusters as two-electron superatoms, that is, a [Cu13]11+ core passivated by ten monoanionic ligands, with an a1 HOMO containing two 1S jellium electrons. [ABSTRACT FROM AUTHOR]

We report the synthesis, characterization, crystal structures, nonlinear-optical (NLO) properties, and density functional theory (DFT) calculations of nickel(ii) and copper(ii) complex based ONO tridentate Schiff base ligands: two mononuclear compounds, [Ni(An-ONO)(NC5H5)] (5) and [Cu(An-ONO)(4-NC5H4C(CH3)3)] (6), and two heterobimetallic species, [M(Fc-ONO)(NC5H5)] (M = Ni, 7; Cu, 8), where An-ONOH2 (3) and Fc-ONOH2 (4) are the 1 : 1 condensation products of 2-aminophenol and p-anisoylacetone and ferrocenoylacetone, respectively. These compounds were characterised by microanalysis, FT-IR and X-ray crystallography in the solid state and in solution by UV-vis and 1H and 13C NMR spectroscopy. The crystal structures of 3–5, 7 and 8 have been determined and show for Schiff base complexes 5, 7 and 8 a four-coordinated square-planar environment for nickel and copper ions. The electrochemical behavior of all derivatives 3–8 was investigated by cyclic voltammetry in dichloromethane, and discussed on the basis of DFT-computed electronic structures of the neutral and oxidized forms of the compounds. The second-order NLO responses of 3–8 have been determined by harmonic light scattering measurements using a 10−2 M solution of dichloromethane and working with a 1.91 μm incident wavelength, giving rather high β1.91 values of 350 and 290 × 10−30 esu for the mononuclear species 5 and 6, respectively. The assignment and the nature of the electronic transitions observed in the UV-vis spectra were analyzed using time-dependent (TD) DFT calculations. They are dominated by LMCT, MLCT and π–π* transitions. [ABSTRACT FROM AUTHOR]

The range of molybdenum hydride complexes that are sought to participate in the important catalytic hydrodenitrogenation process (HDN) of nitrogen containing polycyclic aromatic hydrocarbons were evaluated by DFT studies. The previously synthesized stable (η6-quinoline)Mo(PMe3)3 complex 1N, in which molybdenum is bonded to the heterocyclic ring, was chosen as a model. The hydrogenation of the quinone heterocycle, which was postulated as the initial step in the overall HDN reaction, is found to occur via three consecutive steps of the oxidative addition of dihydrogen to Mo in 1N. Successive transfer of hydrogen atoms from the metal to the heterocycle leads to the ultimate formation of the tetrahydrido molybdenum intermediate Mo(PMe3)4H413 and 2,2,3,3-tetrahydroquinoline C9H11N 14. All the involved intermediates and transition states have been fully characterized by DFT. This computational modeling of the hydrogenation of quinoline, as a part of extended HDN catalytic processes, provides a fundamental understanding of such mechanisms. [ABSTRACT FROM AUTHOR]

An air- and moisture-stable nanoscale polyhydrido copper cluster [Cu32(H)20{S2P(O iPr)2}12] ( 1H) was synthesized and structurally characterized. The molecular structure of 1H exhibits a hexacapped pseudo-rhombohedral core of 14 Cu atoms sandwiched between two nestlike triangular cupola fragments of (2×9) Cu atoms in an elongated triangular gyrobicupola polyhedron. The discrete Cu32 cluster is stabilized by 12 dithiophosphate ligands and a record number of 20 hydride ligands, which were found by high-resolution neutron diffraction to exhibit tri-, tetra-, and pentacoordinated hydrides in capping and interstitial modes. This result was further supported by a density functional theory investigation on the simplified model [Cu32(H)20(S2PH2)12]. [ABSTRACT FROM AUTHOR]

The structures, electronic properties, stabilities, mechanisms, and activation barriers of the intramolecular inter-ring haptotropic rearrangements (η6,η6-IRHRs) of chromium tricarbonyl and chromium benzene complexes of graphene were modeled by DFT calculations. All of the above calculated characteristics are in good agreement with the experimental data for related complexes with ultralarge, large, and medium-sized polyaromatic ligands (PALs). Generally η6,η6-IRHRs between isomer complexes with organometallic groups (OMGs) in different positions in graphene ligand proceeds via η3-transition states with activation barriers considerably lower (<25 kcal/mol) than those of the corresponding rearrangements in medium-sized PALs (>30 kcal/mol). This could be explained by the reduction of electron density and the increase of electron mobility inside graphene molecules, which weaken metal-ligand bonds and facilitate rearrangements. [ABSTRACT FROM AUTHOR]

We have recently reported a series of neutral square planar tridentate Schiff base (L) complexes of the general formula [(L)M(py)], showing relatively high first-order hyperpolarizabilities and NLO redox switching behavior. In the present study, new members of this family of compounds have been prepared with the objective to investigate their potential as building blocks in the on-demand construction of D-π-A push–pull systems. Namely, ternary nickel(II) building blocks of general formula [(LA/D)Ni(4-pyX)] (4–7), where LA/D stands for an electron accepting or donating dianionic O,N,O-tridentate Schiff base ligand resulting from the monocondensation of 2-aminophenol or its 4-substituted nitro derivative and β-diketones R-C(=O)CH2C(=O)CH3 (R = methyl, anisyl, ferrocenyl), and 4-pyX is 4-iodopyridine or 4-ethynylpyridine, were synthesized and isolated in 60–78% yields. Unexpectedly, the Sonogashira cross-coupling reaction between the 4-iodopyridine derivative 6 and 4-ethynylpyridine led to the formation of the bis(4-pyridyl) acetylene bridged centrosymmetric dimer [{(LD)Ni}2(µ2-py-C≡C-py)] (8). Complexes 4–8 were characterized by elemental analysis, FT-IR and NMR spectroscopy, single crystal X-ray diffraction and computational methods. In each compound, the four-coordinate Ni(II) metal ion adopts a square planar geometry with two nitrogen and two oxygen atoms as donors occupying trans positions. In 8, the Ni...Ni separation is of 13.62(14) Å. Experimental results were proved and explained theoretically exploiting Density Functional Theory calculations. [ABSTRACT FROM AUTHOR]

Density functional theory (DFT) calculations were carried out on a series of clusters made of a centered tetrahedral 16‐atom superatomic cage having 20 or 18 jellium electrons (je) and structurally related to [Au20], namely [X@M16] (M = group 11; X = group 2, 4, 12, 14 element). Such species provide further information of how two different electron counts offer a more preferred endohedral situation for specific group elements. Calculations show that the encapsulated atom provides supplementary orbitals to stabilize the bonding M16 MO's. Different favored electron counts are found depending on the nature of the encapsulated atom, as observed by the formation of 20‐je species when encapsulating a group 14 element and 18‐je species when encapsulating a group 2 element. In addition, the capabilities to enable reactive sites along the cage structure are found via the formation of σ holes at the coinage‐metal edges, as shown by their electrostatic potential surface. Such naked species, which constitute an interesting addition to libraries of examples as small models for doped M(111) surfaces of fcc metals, reveal that different superatomic electronic configurations can favor the encapsulation of certain group elements. These results can guide further design of endohedral species. [ABSTRACT FROM AUTHOR]

Attempts to expand the versatility of well defined clusters are a relevant issue in the design of building blocks for functional nanostructures. Here, we investigate the plausible formation of related structures from the emblematic highly symmetrical 18‐e [W@Au12] cluster. The calculated [W@Au12Ptn] series, with n = 0, 1, 2, 3, and 4, show cohesion energies, HOMO‐LUMO gap, adiabatic electron affinities (AEAs) and adiabatic ionization potentials (AIPs), indicating a relative stability to the parent cluster [W@Au12] experimentally characterized, where clusters with n = 1 and n = 4 are suggested as the most stable with respect to oxidation. The resulting symmetry lowering away from the high icosahedral symmetry upon adding Pt atoms induces a sizable splitting of the frontiers shells, which in turn effectively modify the properties of the calculated clusters, as observed from calculated optical properties. The estimated absorption spectra show an interesting broadening effect of the absorption peaks, which appears as a useful approach for further design of broad black absorbers, which are able to absorb light in a wider range, with potential capabilities to enhance the efficiency of thin film solar cells and photocatalysis processes, among other applications. Cage doping induces structural modifications along the isoelectronic series given by W@Au12Ptn (n = 0‐4) superatomic clusters, highlight the role of symmetry changes in optical and energetic properties. Such changes are related to interesting broadening effect of the absorption peaks, which can be taken into account in the design of improved broad black‐absorbers. [ABSTRACT FROM AUTHOR]

DFT calculations have been performed on a series of heterobimetallic compounds of the type [MCp][M′Cp](Ind), [M(CO)3][M′(CO)3](Ind) and [M(CO)2][M′(CO)3](Ind) (Ind = Indenyl). The flexibility of the indenyl ligand favors the possibility of the existence of several isomers. The structure and electronic structure of this large family of compounds were analyzed with respect to their total number of electrons (TNE) and the nature of the ancillary ligands. The structures with electron counts lower than 34-TNE adopt the syn configuration to compensate the electronic deficiency. [ABSTRACT FROM AUTHOR]

Unsubstituted bis-indenylchromium has been shown to be a dimer, Cr 2 (Ind) 4 , whereas the monomeric sandwich-type structure, Cr(Ind) 2 , has been only observed for substituted relatives. DFT calculations indicate that dimerization allows the building of a quadruple Cr-Cr bond whereas it can still participate in five formal 2-electron metal-ligand bonds. Despite of this apparently favorable situation with respect to dimer stability, the energetic balance in favor of the dimer is computed not to be very large. Calculations on a series of related Cr, Mn, Fe and Co relatives indicate that Cr 2 (Ind) 4 appears unique in terms of its stability relatively to its monomer. However, dimeric species such as Cr 2 (Cp) 2 (Ind) 2 , Cr 2 (Cp) 4 or Mn 2 (Ind) 4 appear to be not that much unstable relatively to their monomer for being observed under some specific circumstances. [ABSTRACT FROM AUTHOR]

Abstract: Thirteen novel dipolar and V-shaped chromophores with pyranylidene electron-donating part, diazine electron-withdrawing part and various π-linkers were synthesized. The extent of intramolecular charge transfer, structure-property relationships and optical properties were further investigated by UV/Vis absorption, electrochemistry, and DFT calculations. [Copyright &y& Elsevier]

In this paper we describe the synthesis, the electrochemical behaviour as well as the linear and nonlinear optical (NLO) properties of two push-pull derivatives bearing pyranylidene electron donating fragment, pyrimidine/methyl pyrimidinium electron withdrawing moiety and a ferrocene part in the π-conjugated bridge. The properties of these two compounds were compared to their analogues without ferrocene or pyranylidene fragments. Experimental results were completed with DFT calculations to gain further insight into the intramolecular charge transfer (ICT). All the results indicate a significant charge transfer through the ferrocene unit. The ICT is however more limited than in all organic analogues. [ABSTRACT FROM AUTHOR]

The structural peculiarities (C1-C6 distances, bending of the ligand, conformation of organometallic group relative to the ligand, etc.), the isomerism and the mechanisms of inter-ring haptotropic rearrangements (IRHR) in Cr(CO) 3 and CoCp complexes of 1,6-methano[10]annulene were investigated by DFT. An activation barrier of 28.0 kcal/mol, lower than that corresponding to naphthalene, was computed for the η 6 , η 6 -IRHR in the mononuclear chromium complex. In the case of the mononuclear cobalt species, activations barrier of 33.8 and 31.3 kcal/mol were computed for the η 4 , η 4 -IRHR in the trans and cis isomers, respectively. [ABSTRACT FROM AUTHOR]

In this work, we present the synthesis of the unsymmetrical β-diketone 1-(2-thienyl)-3-(4-fluorophenyl)-propane-1,3-dione ( HL) and its corresponding Co(II), Ni(II) and Cu(II) bis (β-diketonato) complexes 1 – 3 , respectively. The four new compounds were isolated in good yields (65–70%), and characterized by mass spectrometry, elemental analysis, FT-IR and UV–Vis spectroscopy and, in the case of HL, by 1 H, 13 C and 19 F NMR spectroscopy. In addition, the molecular identities and the geometries of the β-diketone HL and complex 3 were confirmed by X-ray diffraction analysis. The dicarbonyl derivative HL does exist as the diketo tautomeric form in DMSO solution and as its keto-enol tautomer in the solid-state with the OH group adjacent to the 4-fluorophenyl unit. The keto-enol isomer was computed to be more stable by 8.2 kcal/mol in free energy at room temperature. In 3 , the Cu(II) center adopts a perfect square-planar geometry. Two reduction processes were observed in the cyclovoltammogram of 3 at −1.30 and −1.80 V vs. Fc/Fc + , with copper deposit on the surface of the electrode. DFT and TD-DFT calculations on HL and complex 3 allow rationalizing their stability, bonding and properties. [ABSTRACT FROM AUTHOR]

Inter-ring haptotropic rearrangements (IRHRs) are well-known phenomena in fluxional ogranometallic chemistry. They are mainly observed for transition metal complexes with polyaromatic ligands (PALs), but are usually limited to PALs without heteroatoms. Here, we report DFT studies of recent experimentally observed IRHRs in heterocyclic complexes of Mo. Four different ligands (quinoline, isoquinoline, quinoxaline, and indolyl) have been investigated. Overall, structural and energetic trends agree well with available experimental data. In addition, mechanistic trends and heteroatom participation are discussed and elucidated to further understanding of IRHRs in heterocyclic polyaromatic complexes in particular, and haptotropic processes in general. [ABSTRACT FROM AUTHOR]

Ferrocenyl-chalcones and their bichalcone analogues were characterized by IR and NMR spectroscopy, as well as electrochemically. Their UV–visible spectra were recorded, and the electronic transitions were assigned by time-dependent DFT calculations. The single-crystal X-ray structures were determined for two ferrocenyl bichalcones. [ABSTRACT FROM AUTHOR]

The isomerization reactions of Fe(C 8 H 6 ) 2 and Fe(C 10 H 8 ) 2 have been investigated by the means of DFT calculations. Several low-energy isomers having a C–C bond linking the two ligands exist in both cases, in addition to an isomer in which the two ligands are not connected. Calculation show that, apart one exception in the bis(azulenyl)iron case, all the isomerization reactions are formal intramolecular redox processes. These reactions are under symmetry control and related to the nodal properties of the non-coupled bis(pentalene) iron LUMO and bis(azulene)iron HOMO, respectively. Although most of the isomer interconversion are symmetry-forbidden, the intramolecular racemization of the experimentally characterized isomers of bis(pentalenyl)iron and bis(azulenyl)iron are allowed and should be observed. [ABSTRACT FROM AUTHOR]

Abstract: Ruthenaborane clusters have been modelled by performing density functional theory calculations using the B3LYP functional. The calculations gain insights into hydrogen storage and the H–H bond activation by ruthenaboranes. To study the nature of the chemical bond of H2 molecules attached to ruthenaboranes, we carried out structural optimizations for different ruthenaborane clusters and determined transition state structures for their hydrogenation addition/elimination reactions. Calculations of the reaction pathways yielded different transition-state structures involving molecular hydrogen bonded to the cluster or formation of metal hydrides. The H–H bond of H2 seems to be activated by the ruthenaborane clusters as activation energies of 24–42 kcal/mol were calculated for the H2 addition reaction. The calculated Gibbs free energy for the H2 addition reaction is 14–27 kcal/mol. The calculated activation energies and the molecular structures of the [(C5Me5)Ru2B10H16], [(C5Me5)Ru2B8H14] and [(C5Me5)Ru2B8H12] clusters with different degree of hydrogenation are compared. The mechanisms of the H2 addition and elimination reactions of the studied clusters suggest that they might be useful as hydrogen storage materials due to their ability to activate the H–H bond. They also serve as an example of the ability of hypoelectronic metallaboranes to reversibly or irreversibly bind hydrogen. [Copyright &y& Elsevier]

A series of luminescent chloro- and alkynyl-platinum (II) complexes containing various tridentate cyclometalated ligands derived from phenyl-pyridin-2-ylpyrimidine and alkynyl ligands has been successfully synthesized and characterized. Their electrochemical, electronic absorption and luminescence properties have been experimentally investigated and supported by (Time-Dependent) Density Functional Theory ((TD)-DFT) calculations. Electrochemical studies show the presence of a ligand-centered reduction originating from the cyclometalating N^N^C ligands, as well as a major ligand-centered oxidation process (N^N^C or alkynyl) with minor contributions of the metal. Most of the complexes exhibits yellow-to-red luminescence at room-temperature in diluted solutions, in frozen matrices and in the solid state. Electron-withdrawing groups on the alkynyl-ligand induce a red shift of the emission band with increased quantum yield in solution. The emission is also sensitive to the position of the pyridyl fragment on the pyrimidine core: complexes with electron-poorer 4-pyridin-2-ylpyrimidine ligands exhibit red-shifted emission and decreased quantum yield compared to their 2-pyridin-4yl analogues. In solid state, chloro-platinum complexes without t Bu bulky group exhibit red-shifted excimer emission. [Display omitted] • Chloro- and alkynyl-platinum(II) complexes based on phenyl-pyridin-2-ylpyrimidine ligand were synthesized and characterized. • Yellow-to-red emission was observed for most of the complexes in solution and in solid state. • The position of the pyridyl group on the pyrimidine ligand plays a significant role in the properties of complexes. • Electron-withdrawing groups on the alkynyl-ligand induce a red shift of the emission band with increased quantum yield in solution. [ABSTRACT FROM AUTHOR]