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1.
Chem Commun (Camb) ; 2020 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-32666980

RESUMO

Two mixed-metal hydride clusters, corresponding to x = 3 and 4, were structurally characterized from a set of atomically precise heptanuclear clusters, CuxAg7-x(H){S2P(OiPr)2}6 (x = 1-6). An interstitial hydride lying at the center of a tricapped tetrahedral cage was located and refined anisotropically by using X-ray data, and its presence acertained by multinuclear NMR spectroscopy and DFT calculations.

2.
Inorg Chem ; 2020 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-32578989

RESUMO

Reaction of the Cu(I) sources, [Cu5](Mes)5 and [(iDipp)CuOtBu] (Mes = mesityl; iDipp = 1,3-bis(2,6-diisopropylphenyl)-1H-imidazol-2-ylidene) with the Zn(I) complex [Zn2](Cp*)2 leads to a mixture of intermetallic Cu/Zn clusters with a distribution of species that is dependent on the stoichiometric ratio of the reactants, the reaction time, as well as the temperature. Systematic and careful investigation of the product mixtures rendered the isolation of two new clusters possible, i.e., the Zn-rich, red cluster 1, [CuZn10](Cp*)7 = [Cu(ZnZnCp*)3(ZnCp*)4], as well as the Cu-rich, dark-green cluster 2 [Cu10Zn2](Mes)6(Cp*)2. Structure and bonding of these two species was rationalized with the help of density functional theory calculations. Whereas 1 can be viewed as an 18-electron Cu center coordinated to four ZnCp* and three ZnZnCp* one-electron ligands (with some interligand bonding interaction), compound 2 is better to be described as a six-electron superatom cluster. This unusual electron count is associated with a prolate distortion from a spherical superatom structure. This unexpected situation is likely to be associated with the ZnCp* capping units that offer the possibility to strongly bind to the top and the bottom of the cluster in addition to the bridging mesityl ligands stabilizing the Cu core of the cluster.

3.
Chemistry ; 2020 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-32378767

RESUMO

Although atomically precise polyhydrido copper nanoclusters are of prime interest for a variety of applications, they have so far remained scarce. Herein, this work describes the synthesis of a dithiophosphate-protected copper(I) hydride-rich nanocluster (NC), [Cu30 H18 {S2 P(OnPr)2 }12 ] (1H ), fully characterized by various spectroscopic methods and single-crystal X-ray diffraction. The X-ray structure of 1H reveals an unprecedented central Cu12 hollow icosahedron. Six faces of this icosahedron are capped by Cu3 triangles, the whole Cu30 core being wrapped by twelve dithiophosphate ligands and the whole cluster has ideal S6 symmetry. The locations of the 18 hydrides in 1H were ascertained by a single-crystal neutron diffraction study. They are composed of three types: capping µ3 -H, interstitial µ4 -H (seesaw) and µ5 -H ligands (square pyramidal), in good agreement with the DFT simulations. The numbers of hydrides and ligand resonances in the 1 H NMR spectrum of 1H are in line with their coordination environment in the solid state, retaining the S6 symmetry in solution. Furthermore, two new Se-protected polyhydrido copper nanoclusters, [Cu30 H18 {Se2 P(OR)2 }12 ] (2H : R=iPr 3H : R=iBu) were synthesized from their sulfur relative 1H via ligand displacement reaction and their X-ray structures feature the exceptional case where both the NC shape and size are fully conserved during the course of ligand exchange. DFT and TD-DFT calculations allow understanding the bonding and optical properties of clusters 1H -3H . In addition, the reaction of 1H with [Pd(PPh3 )2 Cl2 ] in the presence of terminal alkynes led to the formation of new bimetallic Cu-Pd alloy clusters [PdCu14 H2 {S2 P(OnPr)2 }6 (C≡CR)6 ] (4: R=Ph; 5: R=C6 H4 F).

4.
Chemistry ; 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-32045497

RESUMO

The electronic structure of the spherical Mackay icosahedral nanosized cluster Pd55 (PiPr3 )12 (µ3 -CO)20 is analyzed by using DFT calculations. Results reveal that it can be considered as a regular superatom with a "magic" electron count of 20, characterized by a 1S2 1P6 1D10 2S2 jellium configuration. Its open shell nature is associated with partial occupation of non-jellium, 4d-type, levels located on the interior of the Pd55 kernel. This shows that the superatom model can be used to rationalize the bonding and stability of spherical ligated group 10 clusters, despite their apparent 0-electron count.

5.
Artigo em Inglês | MEDLINE | ID: mdl-32091662

RESUMO

Reported here is a readily available bis(imino)carbazole-based proligand that constitutes a convenient entry point into the challenging synthetic molecular chemistry of barium. It enables the preparation of rare or even, up to now, unknown, solution-stable heteroleptic barium complexes. The syntheses and structural features for the first molecular barium fluoride and the first barium stannylide, with an unsupported Ba-Sn bond, are described, along with other carbazolate barium species: an amide (both a remarkably stable starting material and an excellent hydrophosphination precatalyst), iodide, and silanylide. DFT analysis of bonding patterns in the barium stannylide and barium silanylide highlights a prevailingly ionic barium-tetrelide bond with a small covalent contribution.

6.
Inorg Chem ; 59(3): 1917-1927, 2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-31934757

RESUMO

Irradiation of [Re2(CO)10] in the presence of BH3·thf resulted in the formation of several rhenium diborane(6) species, for example, [{(OC)4Re}{Re(CO)3}2(µ3-η2:η2:η2-B2H6)(µ-H)], 1; [{(OC)4Re}2{Re(CO)3}(µ3-η2:η2:η1-B2H6)(µ-H)], 2; and [{(OC)4Re}2(µ-η2:η2-B2H6)], 3, comprising diverse coordination modes of the [B2H6]2- ligand. Compound 1 contains a tris(bidentate) [B2H6]2- unit, whereas 2 consists of an unsymmetrically bound [µ3-η2:η2:η1-B2H6]2- ligand. In contrast, the irradiation of [Mn2(CO)10] with BH3·thf yielded only the Mn analogue of 1, [{(OC)4Mn}{Mn(CO)3}2(µ3-η2:η2:η2-B2H6)(µ-H)], 1'. In an attempt to generate the bimetallic Mn-diborane(6), we have carried out the reaction of 1' with PCy3 under photolytic conditions. The reaction led to the formation of two single base stabilized unsymmetrical diborane(5) species, [{Mn(CO)3}{Mn(CO)2PCy3}(µ-η2:η2-B2H5·PCy3)(µ-H)], 4, and [{Mn(CO)2PCy3}(η3-B2H5·PCy3)], 5. As [B2H6]2- and [B2H5·PCy3]- are isoelectronic, the bondings in 4 and 5 are analogous to that of diborane(6) species 1-3. All the new species have been characterized spectroscopically, and their structures were further confirmed by single-crystal X-ray diffraction studies. DFT-type quantum chemical calculations were carried out that provided insight into the bonding interaction of [B2H6]2- and [B2H5·PCy3]- with the M(CO)n fragments.

7.
Inorg Chem ; 2020 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-31977197

RESUMO

Structurally precise copper hydrides [Cu11H2{S2P(OiPr)2}6(C≡CR)3], R = Ph (1), C6H4F (2), and C6H4OMe (3), were first synthesized from the polyhydrido copper cluster [Cu20H11{S2P(OiPr)2}9] with nine equivalents of terminal alkynes. Later, their isolated yields were significantly improved by direct synthesis from [Cu(CH3CN)4](PF6), [NH4][S2P(OiPr)2], NaBH4, and alkynes along with NEt3 in THF. 1, 2, and 3 were fully characterized by single-crystal X-ray diffraction, ESI-MS, and multinuclear NMR spectroscopy. All three clustershave 11 copper atoms, adopting 3,3,4,4,4-pentacapped trigonal prismatic geometry, with two hydrides inside the Cu11 cage, the position of which was ascertained by a single-crystal neutron diffraction structure of cluster 1 co-crystallized with a [Cu7(H){S2P(OiPr)2}6] (4) cluster. Six dithiophosphate and three alkynyl ligands stabilize the Cu11H2 core in which the two hydrides adopt a trigonal pyramidal coordination mode. This coordination mode is so far unprecedented for hydride. The 1H NMR resonance frequency of the two hydrides appears at 4.8 ppm, a value further confirmed by 2H NMR spectroscopy for their deuteride derivatives [Cu11(D)2{S2P(OiPr)2}6(C≡CR)3]. A DFT investigation allows understanding the bonding within this new type of copper(I) hydrides.

8.
J Am Chem Soc ; 141(50): 19570-19574, 2019 Dec 18.
Artigo em Inglês | MEDLINE | ID: mdl-31736293

RESUMO

Peripherally substituted tetradecaazaheptacene (N14Hp) compounds, exhibiting amphiprotism-coupled emission, have been synthesized. X-ray crystallography reveals a planar acene-like chromophore, and electronic absorption and emission occur in the near-infrared biological transparency window (650-900 nm). The compounds exhibit long-wavelength emission with photoluminescence quantum yields ΦPL up to ∼0.61 at 686 nm, with the monodeprotonated state ΦPL ≈ 0.58 at 712 nm. This unprecedented highly nitrogenous chromophore illustrates the stability and utility of the pyrazinacenes for different applications based on their photophysical properties and chemical structures.

9.
J Am Chem Soc ; 141(33): 12957-12961, 2019 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-31378060

RESUMO

Three bimetallic platinum/silver nanoclusters, PtAg20(dtp)12 (1), Pt2Ag33(dtp)17 (2), and Pt3Ag44(dtp)22 (3) (dtp: dipropyl dithiophosphate), with cluster electron counts of 8, 16, and 22, respectively, were produced via a one-phase coreduction method. Single-crystal X-ray structures reveal that their inner cores can be visualized as consisting of one, two, and three centered icosahedral Pt@Ag12 units, respectively. In 2 and 3, these units are vertex-sharing and are assembled linearly. Intriguingly, the 22-electron alloy (3) is isolobal to the linear triiodide anion, I3-, and represents the first example of a cluster made of three superatoms whose bonding characteristics are similar to those of a triatomic molecular species.

10.
Chemistry ; 25(59): 13509-13513, 2019 Oct 22.
Artigo em Inglês | MEDLINE | ID: mdl-31411764

RESUMO

The first unsupported barium siloxide, the homoleptic dimer [Ba2 {µ2 -OSi(SiMe3 )3 }3 {OSi(SiMe3 )3 }], is presented, and its structural features are discussed in the light of DFT computations. This complex, together with the related [Ba{µ2 -OSi(SiMe3 )3 }{N(SiMe3 )2 }]2 and their parent [Ba{N(SiMe3 )2 }2 ]2 , mediates the formation of asymmetric siloxanes R3 Si-O-SiR'3 through the first case of main group metal-mediated dehydrocoupling of silanols and hydrosilanes. Early kinetic analysis highlights an unusual catalytic manifold.

11.
Nanoscale ; 11(31): 14581-14586, 2019 Aug 08.
Artigo em Inglês | MEDLINE | ID: mdl-31359023

RESUMO

The synthesis, via a co-reduction method, of the first Pd-containing silver-rich 21-metal-atom nanocluster passivated by dithiolates, [PdAg20{S2P(OnPr)2}12] (1), is reported. 1 is an 8 electron superatom isoelectronic to [Ag21{S2P(OiPr)2}12]+. The doping of Pd in 1 leads to its high stability against degradation in solution and shows red emission in MeTHF at 77 K. In addition, we report the X-ray crystal structure of a multi-palladium doped silver nanocluster, [Pd6Ag14(S){S2P(OnPr)2}12] (2), for the first time. Its X-ray structure exhibits a sulfide-centered Pd6Ag2 rhombohedron surrounded by twelve additional silver atoms with S6 symmetry. The XPS study and DFT calculations indicate that 2 contains Pd(0) and Ag(i) metals. A significant decrease in the electrochemical gap was observed in the SWVs of 2.

12.
Phys Chem Chem Phys ; 21(16): 8428-8433, 2019 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-30945710

RESUMO

DFT calculations were carried out on a series of tetrahedral 16-atom superatomic clusters having 20 or 18 jellium electrons (je) and structurally related to Au20, namely, [M16]4-/2- (M = Cu, Ag, and Au) and [M4'M12'']0/2+ (M' = Zn, Cd, Hg; M'' = Cu, Ag, Au). While the bare homonuclear 20-je species required further stabilization to be isolated, their 18-je counterparts exhibited better stability. Lowering the electron count led to structural modification from a compact structure (20-je) to a hollow sphere (18-je). Such a change could be potentially controlled by tuning redox properties. Among the 20-je heteronuclear [M4'M12''] neutral series, [Zn4Au12] appeared to meet the best stability criteria, but their 18-je relatives [M4'M12'']+, in particular [Zn4Cu12]2+ and [Cd4Au12]2+, offered better opportunities for obtaining stable species. Such species exhibit the smallest models for the M(111) surface of fcc metals, which expose designing rules towards novel high-dopant-ratio clusters as building blocks of nanostructured materials.

13.
Chemistry ; 25(37): 8854-8864, 2019 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-31026099

RESUMO

A set of calcium and barium complexes containing the fluoroarylamide N(C6 F5 )2 - is presented. These compounds illustrate the key role of stabilising M⋅⋅⋅F-C secondary interactions in the construction of low-coordinate alkaline earth complexes. The nature of Ca⋅⋅⋅F-C bonding in calcium complexes is examined in the light of structural data, bond valence sum (BVS) analysis and DFT computations. The molecular structures of [Ca{N(C6 F5 )2 }2 (Et2 O)2 ] (4'), [Ca{µ-N(SiMe3 )2 }{N(C6 F5 )2 }]2 (52 ), [Ba{µ-N(C6 F5 )2 }{N(C6 F5 )2 }⋅toluene]2 (62 ), [{BDIDiPP }CaN(C6 F5 )2 ]2 (72 ), [{N^NDiPP }CaN(C6 F5 )2 ]2 (82 ), and [Ca{µ-OB(CH(SiMe3 )2 )2 }{N(C6 F5 )2 }]2 (92 ), where {BDIDiPP }- and {N^NDiPP }- are the bidentate ligands CH[C(CH3 )NDipp]2 - and DippNC6 H4 CNDipp- (Dipp=2,6-iPr2 -C6 H3 ), are detailed. Complex 62 displays strong Ba⋅⋅⋅F-C contacts at around 2.85 Å. The calcium complexes feature also very short intramolecular Ca-F interatomic distances at around 2.50 Å. In addition, the three-coordinate complexes 72 and 82 form dinuclear structures due to intermolecular Ca⋅⋅⋅F-C contacts. BVS analysis shows that Ca⋅⋅⋅F-C interactions contribute to 15-20 % of the bonding pattern around calcium. Computations demonstrate that Ca⋅⋅⋅F-C bonding is mostly electrostatic, but also contains a non-negligible covalent contribution. They also suggest that Ca⋅⋅⋅F-C are the strongest amongst the range of weak Ca⋅⋅⋅X (X=F, H, Cπ ) secondary interactions, due to the high positive charge of Ca2+ which favours electrostatic interactions.

14.
Angew Chem Int Ed Engl ; 58(15): 4943-4947, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30770621

RESUMO

The structurally precise Cu-rich hydride nanoclusters [PdCu14 H2 (dtc/dtp)6 (C≡CPh)6 ] (dtc: di-butyldithiocarbamate (1); dtp: di-isopropyl dithiophosphate (2)) were synthesized from the reaction of polyhydrido copper clusters [Cu28 H15 (S2 CNn Bu2 )12 ]+ or [Cu20 H11 {S2 P(Oi Pr)2 }9 ] with phenyl acetylene in the presence of Pd(PPh3 )2 Cl2 . Their structures and compositions were determined by single-crystal X-ray diffraction and the results supported by ESI-mass spectrometry. Hydride positions in 1 were confirmed by single-crystal neutron diffraction. Each hydride is connected to one Pd0 and four CuI atoms in slightly distorted trigonalbipyramidal geometry. The anatomies of clusters 1 and 2 are very similar and DFT calculations allow rationalizing the interactions between the encapsulated [PdH2 ]2- unit and its Cu14 bicapped icosahedral cage. As a result, Pd has the highest coordination number (14) so far recorded.

15.
Chem Sci ; 9(33): 6785-6795, 2018 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-30310611

RESUMO

We have synthesized and structurally characterized a series of centred cuboctahedral copper clusters, namely [Cu13{S2CNR2}6{C[triple bond, length as m-dash]CR'}4](PF6), 1a-d (where a: R = n Bu, R' = CO2Me; b: R = n Bu, R' = CO2Et; c: R = iPr, R' = CO2Et; d: R = n Pr, R' = 3,5-(CF3)2C6H3); [Cu12(µ12-S){S2CNR2}6{C[triple bond, length as m-dash]CR'}4], 2a-c; [Cu12(µ12-Cl){S2CNR2}6{C[triple bond, length as m-dash]CR'}4](PF6), 3a-e (where e: R = n Bu, R' = Ph); [Cu12(µ12-Br){S2CN n Bu2}6{C[triple bond, length as m-dash]CPh}4](PF6), 4e; and [Cu12(µ12-Cl)(µ3-Cl){S2CN n Bu2}6{C[triple bond, length as m-dash]CCO2Me}3]+ 5a. Cluster 1a is the first structurally characterized copper cluster having a Cu13 centered cuboctahedral arrangement, a miniature of the bulk copper fcc structure. Furthermore, the partial Cu(0) character in the 2-electron superatoms 1 was confirmed by XANES. Inverse coordination clusters 2-5 are the first examples of copper clusters containing main group elements (Cl, Br, S) with a hyper-coordination number, twelve. A combined theoretical and experimental study was performed, which shows that the central copper (formally Cu1-) in nanoclusters 1 can be replaced by chalcogen/halogen atoms, resulting in the formation of clusters 2-5 which show enhanced luminescence properties and increase in the ionic component of the host-guest interaction as Br ≈ Cl > S > Cu, which is consistent with the Cu-X Wiberg indices. The new compounds have been characterized by ESI-MS, 1H, 13C NMR, IR, UV-visible, emission spectroscopy, and the structures 2a-b, 3d-e, 4e and 5a were established by X-ray diffraction analysis.

16.
Angew Chem Int Ed Engl ; 57(44): 14630-14634, 2018 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-29981271

RESUMO

The paramagnetic cluster [Cu43 Al12 ](Cp*)12 was obtained from the reaction of [CuMes]5 and [AlCp*]4 (Cp*=η5 -C5 Me5 ; 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 Cu43 Al12 core.

17.
Dalton Trans ; 47(32): 11123-11135, 2018 Aug 14.
Artigo em Inglês | MEDLINE | ID: mdl-30043792

RESUMO

A new Zn(ii) porphyrin-based dendrimer (52) containing twelve Ru(ii) alkynyl fragments, has been prepared following a convergent approach in two steps from 5,10,15,20-tetra(4-ethynylphenyl)porphyrinatozinc(ii) (6). The cubic nonlinear optical (NLO) properties of 52 and other derivatives of 6 have been measured by third-harmonic generation (THG) at 1907 nm and by Z-scan over the spectral range 500-1700 nm, revealing the remarkable NLO response of 52 in the near-IR range. These results highlight the beneficial role of the extended "cross fourchée"-like polymetallic structure of 52 on its third-order NLO properties.

18.
Chemistry ; 24(54): 14352-14357, 2018 Sep 25.
Artigo em Inglês | MEDLINE | ID: mdl-29968945

RESUMO

A templated galvanic exchange performed on [Ag20 {Se2 P(OiPr)2 }12 ] of C3 symmetry with three equiv AuI yields a mixture of [Au1+x Ag20-x {Se2 P(OiPr)2 }12 ]+ (x=0-2) from which [Au@Ag20 {Se2 P(OiPr)2 }12 ]+ and [Au@Au2 Ag18 {Se2 P(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.

19.
Nanoscale ; 10(15): 6855-6860, 2018 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-29616252

RESUMO

Controlling the metal nanoclusters with atomic precision is highly difficult and further studies on their transformation reactions are even more challenging. Herein we report the controlled formation of a silver alloy nanocluster [AuAg19{S2P(OnPr)2}12] (1) from an Ag20 template via a galvanic exchange route. X-ray structural analysis reveals that the alloy structure comprises of a gold-centered Ag12 icosahedron, Au@Ag12, capped by seven silver atoms. Interestingly upon reacting with one equiv. of silver(i) salt, (1) can transform into a higher nuclearity nanocluster, [Au@Ag20{S2P(OnPr)2}12]+ (2). The conversion process is studied via ESI mass spectrometry and 31P NMR spectroscopy. This kind of size-structural transformation at the single atom level is quite remarkable. Furthermore, the compositions of all the doped nanoclusters (1, 2) were fully characterized with ESI-MS and EDS. The blue shift depicted in the UV-visible and emission spectra of the doped nanoclusters (1, 2) compared with the precursor, Ag20, demonstrates that the doping atoms have significant effects on the electronic structures.

20.
Inorg Chem ; 57(8): 4328-4339, 2018 Apr 16.
Artigo em Inglês | MEDLINE | ID: mdl-29620359

RESUMO

Luminescent materials based on copper complexes are currently receiving increasing attention because of their rich photophysical properties, opening a wide field of applications. The copper iodide clusters formulated [Cu4I4L4] (L = ligand), are particularly relevant for the development of multifunctional materials based on their luminescence stimuli-responsive properties. In this context, controlling and modulating their photophysical properties is crucial and this can only be achieved by thorough understanding of the origin of the optical properties. We thus report here, the comparative study of a series of cubane copper iodide clusters coordinated by different phosphine ligands, with the goal of analyzing the effect of the ligands nature on the photoluminescence properties. The synthesis, structural, and photophysical characterizations along with theoretical investigations of copper iodide clusters with ligands presenting different electronic properties, are described. A method to simplify the analysis of the 31P solid-state NMR spectra is also reported. While clusters with electron-donating groups present classical luminescence properties, the cluster bearing strong electron-withdrawing substituents exhibits original behavior demonstrating a clear influence of the ligands properties. In particular, the electron-withdrawing character induces a decrease in energy of the unoccupied molecular orbitals, that consequently impacts the emission properties. The modification of the luminescence thermochromic properties of the clusters are supported by density functional theory (DFT) calculations. This study demonstrates that the control of the luminescence properties of these compounds can be achieved through modification of the coordinated ligands, nevertheless the role of the crystal packing should not be underestimated.

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