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1.
Dalton Trans ; 2020 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-32343295

RESUMO

Five heterometallic pentanuclear metal strings were prepared by stepwise synthesis from two to three and four kinds of metals aligned in one chain. In particular, NiPtCo2Pd(tpda)4Cl2 (5) possesses four different metals, and the SQUID measurement shows that Ni2+ is the only magnetically active center. Besides, the shortest Co(ii)-Co(ii) single bond (2.105(9) Å), so far, is reported.

2.
J Am Chem Soc ; 142(19): 8649-8661, 2020 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-32279491

RESUMO

Light triggers the formation of HNO from a metal-nitrosyl species, facilitated by an intramolecular pendant thiol proton. Two {FeNO}6 complexes (the Enemark-Felthan notation), [Fe(NO)(TMSPS2)(TMSPS2H)] (1, TMSPS2H2 = 2,2'-dimercapto-3,3'-bis(trimethylsilyl)diphenyl)phenylphosphine; H is a dissociable proton) with a pendant thiol and [Fe(NO)(TMSPS2)(TMSPS2CH3)] (2) bearing a pendant thioether, are spectroscopically and structurally characterized. Both complexes are highly sensitive to visible light. Upon photolysis, complex 2 undergoes NO dissociation to yield a mononuclear Fe(III) complex, [Fe(TMSPS2)(TMSPS2CH3)] (3). In contrast, the pendant SH of 1 can act as a trap for the departing NO radical upon irradiation, resulting in the formation of an intermediate A with an intramolecular [SH···ON-Fe] interaction. As suggested by computational results (density functional theory), the NO stretching frequency (νNO) is sensitive to the intramolecular interaction between the pendant ligand and the iron-bound NO, and a shift of νNO from 1833 (1) to 1823 cm-1 (A) is observed experimentally. Subsequent photolysis of the intermediate A results in HNO production and a thiyl group that then coordinates to the Fe center for the formation of [Fe(TMSPS2)2] (4). In contrast with the common acid-base coupling pathway, the HNO is not voluntarily yielded from 1 but rather is generated by the photopromoted pathway. The photogenerated HNO can further react with [MnIII(TMSPS3)(DABCO)] (TMSPS3H3 = (2,2'2''-trimercapto-3,3',3''-tris(trimethylsilyl)triphenylphosphine; DABCO = 1,4-diazabicyclo[2.2.2]octane) in organic media to yield anionic [Mn(NO)(TMSPS3)]- (5-) with a {MnNO}6 electronic configuration, whereas [MnIII(TMSPS3)(DABCO)] reacts with NO gas for the formation of a {MnNO}5 species, [Mn(NO)(TMSPS3)] (6). Effective differentiation of the formation of HNO from complex 1 with the pendant SH versus NO from 2 with the pendant SMe is achieved by the employment of [MnIII(TMSPS3)(DABCO)].

3.
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.

4.
Chemistry ; 25(30): 7280-7284, 2019 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-30946487

RESUMO

Diindeno-fused dibenzo[a,h]anthracene 6 and diindeno-fused dibenzo[c,l]chrysene 9 contain the key moieties 1,4-quinodipropene (1,4-QDP) and 2,6-naphthoquinodipropene (2,6-NQDP), respectively, and they both have an open-shell singlet ground state. The latter compound exhibits a strong biradical character and interesting properties, including a low ΔET-S (2.44 kcal mol-1 ), a small HOMO-LUMO gap (1.06 eV), a wide photoabsorption range (250-1172 nm), and a large two-photon absorption cross-section (σ=1342±56 GM). This work verifies that 6 has a slightly larger HOMO-LUMO gap and ΔET-S than its helical isomer diindeno[2,1-f:1',2'-j]picene (DIP), but is a much stronger two-photon absorber, verifying the important effect of geometry on the photophysical properties.

5.
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.

6.
Dalton Trans ; 48(2): 379-386, 2019 Jan 02.
Artigo em Inglês | MEDLINE | ID: mdl-30516213

RESUMO

Dioxygen activation by FeII thiolate complexes is relatively rare in biological and chemical systems because the sulfur site is at least as vulnerable as the iron site to oxidative modification. O2 activation by FeII-SR complexes with thiolate bound trans to the O2 binding site generally affords the FeIV[double bond, length as m-dash]O intermediate and oxidized thiolate. On the other hand, O2 activation by Fe(ii)-SR complexes with thiolate bound cis to the O2 binding site generates FeIII-O-FeIII or S-oxygenated complexes. The postulated FeIV[double bond, length as m-dash]O intermediate has only been identified in isopenicillin N synthase recently. We demonstrated here that O2 activation by a dinuclear FeII thiolate-rich complex produces a mononuclear FeIII complex and water with a supply of electron donors. The thiolate is bound cis to the postulated dioxygen binding site, and no FeIII-O-FeIII or S-oxygenated complex was observed. Although we have not detected the transient intermediate by spectroscopic measurements, the FeIV[double bond, length as m-dash]O intermediate is suggested to exist by theoretical calculation, and P-oxidation and hydride-transfer experiments. In addition, an unprecedented FeIII-O2-FeIII complex supported by thiolates was observed during the reaction by using a coldspray ionization time-of-flight mass (CSI-TOF MS) instrument. This is also supported by low-temperature UV-vis measurements. The intramolecular NHO[double bond, length as m-dash]FeIV hydrogen bonding, calculated by DFT, probably fine tunes the O2-activation process for intramolecular hydrogen abstraction, avoiding the S-oxygenation at cis-thiolate.

7.
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.

8.
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.

9.
Inorg Chem ; 57(13): 7620-7630, 2018 Jul 02.
Artigo em Inglês | MEDLINE | ID: mdl-29893554

RESUMO

The intrinsic catalytic property of a Fe-S complex toward H2 evolution was investigated in a wide range of acids. The title complex exhibited catalytic events at -1.16 and -1.57 V (vs Fc+/Fc) in the presence of trifluoromethanesulfonic acid (HOTf) and trifluoroacetic acid (TFA), respectively. The processes corresponded to the single reduction of the Fe-hydride-S-proton and Fe-hydride species, respectively. When anilinium acid was used, the catalysis occurred at -1.16 V, identical with the working potential of the HOTf catalysis, although the employment of anilinium acid was only capable of achieving the Fe-hydride state on the basis of the spectral and calculated results. The thermodynamics and kinetics of individual steps of the catalysis were analyzed by density functional theory (DFT) calculations and electroanalytical simulations. The stepwise CCE or CE (C, chemical; E, electrochemical) mechanism was operative from the HOTf or TFA source, respectively. In contrast, the involvement of anilinium acid most likely initiated a proton-coupled electron transfer (PCET) pathway that avoided the disfavored intermediate after the initial protonation. Via the PCET pathway, the heterogeneous electron transfer rate was increased and the overpotential was decreased by 0.4 V in comparison with the stepwise pathways. The results showed that the PCET-involved catalysis exhibited substantial kinetic and thermodynamic advantages in comparison to the stepwise pathway; thus, an efficient catalytic system for proton reduction was established.

10.
Chemistry ; 24(45): 11649-11666, 2018 Aug 09.
Artigo em Inglês | MEDLINE | ID: mdl-29889320

RESUMO

The heterotrimetallic complexes [FeMFe(dpa)4 Cl2 ] (M=Ni (1), Pd (2), and Pt (3); dpa- =dipyridylamido) featuring two high-spin iron centers linked by Group 10 metals were synthesized and their physical properties were investigated. Oxidation of 1-3 with suitable oxidants in CH2 Cl2 solution yielded the mixed-valent species [1]+/2+ -[3]+/2+ . The solution properties of [1]0/+/2+ -[3]0/+/2+ were characterized by 1 H NMR and UV/Vis/NIR spectroscopy as well as spectroelectrochemisty. The mixed-valent states of [1]+ -[3]+ obtained by electrochemical or chemical oxidation are classified as class II valence delocalization. The solid-state structures of 1-3, [1]+ , [3]+ , and [1]2+ were determined by single-crystal X-ray diffraction analysis, exhibiting a linear metal framework with an approximate D4 symmetry. The spin states and magnetic properties were studied by using SQUID magnetometry, EPR and Mössbauer spectroscopy, and DFT calculations. Antiferromagnetic interactions between terminal high-spin iron centers are present within [1]0/+/2+ -[3]0/+/2+ and the |J| values increase with the central metal ion changing from Ni to Pt. The DFT calculations reproduce the antiferromagnetic coupling and ascribe it to a σ-type exchange pathway. The substitution of the central metal not only influences the spin-spin interactions but also the degree of electronic delocalization between the terminal iron sites along the Fe-M-Fe chains.

11.
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.

12.
Dalton Trans ; 47(5): 1422-1434, 2018 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-29292429

RESUMO

The CoRu2(dpa)4Cl2 (1) (dpa: 2,2'-dipyridylamide) is synthesized by the reaction of Ru2(OAc)4Cl and Co3(dpa)4Cl2. By mixing 1 with NH3, Co2+ can be removed and result in the formation of unique binuclear complex 4,0-Ru2(dpa)4Cl (2) featuring one coordination pocket supported by free pyridine groups. Hence, this complex can act as an outstanding precursor for the formation of heterotrimetallic chains with MRu2 cores. A series of M-Ru25+ complexes (M = Co2+ (3), Ag+ (4), Mn2+ (5), Fe2+ (6), Zn2+ (7), Cd2+ (8), Pd2+ (9), Rh2+ (10), and Ir2+ (11)) were prepared and isolated, representing the most complete series of heterotrimetallic chains to date. All these metal string complexes are in a linear trimetallic framework helically wrapped by four dpa- ligands, characterized by X-ray diffraction measurements. The bending of the trinuclear metal cores in RhRu2 (10) and IrRu2 (11) (∠Ru-Ru-Rh: 167.58° and ∠Ru-Ru-Ir: 167.61°) indicates that a heterometallic metal-metal bonds (Ru-Rh; Ru-Ir) are generated. The studies from DFT calculation of 10 and 11 coincide with the experimental results. Furthermore, the MRu25+ distances are regulated by the factors including the bonding force of M-pyridyl and the static repulsion between M and Ru25+ unit. Interestingly, the trend for these distances is in line with that observed in trans-M(py)4Cl2 complexes.

13.
Chem Asian J ; 13(5): 500-504, 2018 Mar 02.
Artigo em Inglês | MEDLINE | ID: mdl-29363268

RESUMO

Atomically precise Cu-rich bimetallic superatom clusters have been synthesized by adopting a galvanic exchange strategy. [Cu@Cu12 (S2 CNn Bu2 )6 (C≡CPh)4 ][CuCl2 ] (1) was used as a template to generate compositionally uniform clusters [M@Cu12 (S2 CNn Bu2 )6 (C≡CPh)4 ][CuCl2 ], where M=Ag (2), Au (3). Structures of 1, 2 and 3 were determined by single crystal X-ray diffraction and the results were supported by ESI-MS. The anatomies of clusters 1-3 are very similar, with a centred cuboctahedral cationic core that is surrounded by six di-butyldithiocarbamate (dtc) and four phenylacetylide ligands. The doped Ag and Au atoms were found to preferentially occupy the centre of the 13-atom cuboctahedral core. Experimental and theoretical analyses of the synthesized clusters revealed that both Ag and Au doping result in significant changes in cluster stability, optical characteristics and enhancement in luminescence properties.

14.
Angew Chem Int Ed Engl ; 56(34): 10178-10182, 2017 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-28544757

RESUMO

The first atomically and structurally precise silver-nanoclusters stabilized by Se-donor ligands, [Ag20 {Se2 P(Oi Pr)2 }12 ] (3) and [Ag21 {Se2 P(OEt)2 }12 ]+ (4), were isolated by ligand replacement reaction of [Ag20 {S2 P(Oi Pr)2 }12 ] (1) and [Ag21 {S2 P(Oi Pr)2 }12 ]+ (2), respectively. Furthermore, doping reactions of 4 with Au(PPh3 )Cl resulted in the formation of [AuAg20 {Se2 P(OEt)2 }12 ]+ (5). Structures of 3, 4, and 5 were determined by single-crystal X-ray diffraction. The anatomy of cluster 3 with an Ag20 core having C3 symmetry is very similar to that of its dithiophosphate analogue 1. Clusters 4 and 5 exhibit an Ag21 and Au@Ag20 core of Oh symmetry composed of eight silver capping atoms in a cubic arrangement and encapsulating an Ag13 and Au@Ag12 centered icosahedron, respectively. Both ligand exchange and heteroatom doping result in significant changes in optical and emissive properties for chalcogen-passivated silver nanoparticles, which have been theoretically confirmed as 8-electron superatoms.

15.
Angew Chem Int Ed Engl ; 55(47): 14704-14708, 2016 11 14.
Artigo em Inglês | MEDLINE | ID: mdl-27781357

RESUMO

The first structurally characterized copper cluster with a Cu13 centered cuboctahedral arrangement, a model of the bulk copper fcc structure, was observed in [Cu13 (S2 CNn Bu2 )6 (C≡CR)4 ](PF6 ) (R=C(O)OMe, C6 H4 F) 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.

16.
Chemistry ; 22(29): 9943-7, 2016 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-27189869

RESUMO

The synthesis and structural determination of a silver nanocluster [Ag20 {S2 P(OiPr)2 }12 ] (2), which contains an intrinsic chiral metallic core, is produced by reduction of one silver ion from the eight-electron superatom complex [Ag21 {S2 P(OiPr)2 }12 ](PF6 ) (1) by borohydrides. Single-crystal X-ray analysis displays an Ag20 core of pseudo C3 symmetry comprising a silver-centered Ag13 icosahedron capped by seven silver atoms. Its n-propyl derivative, [Ag20 {S2 P(OnPr)2 }12 ] (3), can also be prepared by the treatment of silver(I) salts and dithiophosphates in a stoichiometric ratio in the presence of excess amount of [BH4 ](-) . Crystal structure analyses reveal that the capping silver-atom positions relative to their icosahedral core are distinctly different in 2 and 3 and generate isomeric, chiral Ag20 cores. Both Ag20 clusters display an emission maximum in the near IR region. DFT calculations are consistent with a description within the superatom model of an 8-electron [Ag13 ](5+) core protected by a [Ag7 {S2 P(OR)2 }12 ](5-) external shell. Two additional structural variations are predicted by DFT, showing the potential for isomerism in such [Ag20 {S2 P(OR)2 }12 ] species.

17.
Angew Chem Int Ed Engl ; 54(46): 13604-8, 2015 Nov 09.
Artigo em Inglês | MEDLINE | ID: mdl-26387572

RESUMO

A polyhydrido copper nanocluster, [Cu20H11{Se2P(OiPr)2}9] (2H), which exhibits an intrinsically chiral inorganic core of C3 symmetry, was synthesized from achiral [Cu20H11{S2P(OiPr)2}9] (1H) of C(3h) symmetry by a ligand-exchange method. The structure has a distorted cuboctahedral Cu13 core, two triangular faces of which are capped along the C3 axis, one by a Cu6 cupola and the other by a single Cu atom. The Cu20 framework is further stabilized by 9 diselenophosphate and 11 hydride ligands. The number of hydride, phosphorus, and selenium resonances and their splitting patterns in multinuclear NMR spectra of 2H indicate that the chiral Cu20H11 core retains its C3 symmetry in solution. The 11 hydride ligands were located by neutron diffraction experiments and shown to be capping µ3-H and interstitial µ5-H ligands (in square-pyramidal and trigonal-bipyramidal cavities), as supported by DFT calculations on [Cu20H11(Se2PH2)9] (2H') as a simplified model.

18.
Chemistry ; 21(31): 10978-82, 2015 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-26118674

RESUMO

A reversible and temperature-dependent proton-relay process is demonstrated for a Fe2 complex possessing a terminal thiolate in the presence of nitrogen-based acids. The terminal sulfur site (S(t) ) of the complex forms a hydrogen-bond interaction with N,N-dimethylanilinium acid at 183 K. The Fe2 core, instead, is protonated to generate a bridging hydride at 298 K. Reversibility is observed for the tautomerization between the hydrogen-bonded pair and the Fe-hydride species. X-ray structural analysis of the hydrogen-bonded species at 193 K reveals a short N(H)⋅⋅⋅S(t) contact. Employment of pyridinium acid also results in similar behavior, with reversible proton-hydride interconversion. DFT investigation of the proton-transfer pathways indicates that the pKa value of the hydrogen-bonded species is enhanced by 3.2 pKa units when the temperature is decreased from 298 K to 183 K.

19.
Chemistry ; 21(23): 8369-74, 2015 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-25899822

RESUMO

An air- and moisture-stable nanoscale polyhydrido copper cluster [Cu32 (H)20 {S2 P(OiPr)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 (S2 PH2 )12 ].

20.
Chemistry ; 21(18): 6852-61, 2015 Apr 27.
Artigo em Inglês | MEDLINE | ID: mdl-25776998

RESUMO

The one-electron oxidations of a Fe2 complex lead to the formation of a persistent metal-stabilized thiyl radical Fe2 species, mixed-valent Fe4, and Fe8 complexes. The unpaired spin in the Fe2 radical species delocalizes over the Fe2 and the aromatic dithiolate, mostly on the terminal sulfur. The subsequent dimerization of the singly oxidized Fe2 to the Fe4 retains the partial thiyl radical character. For an analogue with less steric hindrance, the π-π stacking interaction between the dithiolato aromatic rings induces generation of the Fe8, in which process electronic structures of the species are modulated through reducing the thiyl radical to the thiolate. Electronic reorganization repeats when the Fe8 is converted to Fe4. Electronic interplay in the complexes decreases the energy gap of frontier MOs and buffers electronic impacts upon redox events. Easier accessible redox potentials and increased stability of the species are facilitated. The results demonstrate that electronic versatility of the benzenedithiolate exerts pronounced influences on electronic and coordination structure of the metal complexes.


Assuntos
Domínio Catalítico , Complexos de Coordenação/síntese química , Hidrogenase/química , Proteínas com Ferro-Enxofre/química , Ferro/química , Complexos de Coordenação/química , Cristalografia por Raios X , Eletroquímica , Modelos Moleculares , Estrutura Molecular , Oxirredução , Espectrofotometria Infravermelho
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