Transition metal-oxo centers in zeolites are known to be active the conversion of methane methanol. Here, we study this reaction over Fe-oxo sites zeolite SSZ-13. By comparing calculations for fully periodic structure and a cluster two different methods—the standard van der Waals corrected semilocal density functional PBE-D2 ACFDT-RPA, which is method where correlation calculated nonlocally—we find that it actually confining environment reduces barrier reaction, by more than 50%, applied...

Alkali metal zincate reagents are attracting considerable attention at present in respect to their often special reactivity/selectivity hydrogen-metal and halogen-metal interconversion reactions. Heteroleptic diorgano-amidozincates, typified by lithium di-tert-butyltetramethylpiperidinozincate, have proved be especially useful such applications. In this paper the related sodium TMP-zincate, prepared as its TMEDA (N,N,N',N'-tetramethylethylenediamine) adduct,...

Melanins are highly conjugated biopolymer pigments that provide photoprotection in a wide array of organisms, from bacteria to humans. The rate-limiting step melanin biosynthesis, which is the ortho -hydroxylation amino acid L-tyrosine L-DOPA, catalyzed by ubiquitous enzyme tyrosinase (Ty). Ty contains coupled binuclear copper active site binds O 2 form μ:η :η -peroxide dicopper(II) intermediate (oxy-Ty), capable performing regioselective monooxygenation para -substituted monophenols...

Subjecting ferrocene, ruthenocene, or osmocene to the synergic amide base sodium-magnesium tris(diisopropylamido) affords a unique homologous series of metallocene derivatives general formula [(M(C(5)H(3))(2))Na(4)Mg(4)(i-Pr(2)N)(8)] (where M = Fe (1), Ru (2), Os (3)). X-ray crystallographic studies 1-3 reveal common molecular "inverse crown" structure comprising 16-membered [(NaNMgN)(4)](4+) "host" ring and metallocenetetraide [M(C(5)H(3))(2)](4-) "guest" core, cleaved protons which are...

Back to bases: Conventional organometallic bases usually deprotonate toluene at the methyl position generate resonance-stabilized benzyl anions, but using a new type of bimetallic metalation, sodium-mediated magnesiation, thermodynamic for deprotonation can be switched aromatic ring (see picture).

Attractive metallophilic (aurophilic, argentophilic, cuprophilic, etc.) interactions play an important role in arrangement and stabilization of oligonuclear metal ion complexes. We report a combined experimental theoretical assessment aurophilic closed-shell gold(I) dimers. The binding energies were obtained for charged [(LH)AuCl]+...[(L′)AuCl] dimers (L is either phosphine or N-heterocyclic carbene ligand) the gas phase. These served benchmarking correlated quantum chemical calculations...

Inspired by oxidation enzymes such as P450 and TauD, several groups have based their research on the iron–oxo moiety in field of alkanes partial oxidation. Still, controlled cleavage aliphatic C–H bond remains a prized goal chemistry. We present here computational methodology to predict comparative reactivity complexes for this process from linear relations sole electronic structure reactant state. The efficient correlation activation barrier simple but intuitive molecular orbital descriptor...

Highly active and stable inorganic material for dissociation of dioxygen methane oxidation to methanol was developed.

An extensive computational TDDFT resonance Raman study is presented here including forty-two different DFT functionals. The functionals were checked against the experimental FSRS Evolution Associated Spectrum of equilibrated S1 state FMN published earlier. Off-resonance spectra computed first and yielded adequate agreement with spectrum. Fine-tuning correlation was achieved inclusion specific scaling factors for each functional, aimed to align highest peak (symmetric C=O stretch)...

Periodic DFT molecular dynamics and FTIR spectroscopy were used to investigate the cationic sites of ferrierite exchanged with Co(II) Cu(II) their complexes NO. Particular attention was paid effect Al siting in six-membered rings forming on structure these corresponding binding energies Me(II) (Me = Co Cu). Our calculations show that both cations upon induce a rearrangement local zeolite framework. The is significant for α β-2 while it minor β-1 site. Comparison observed theoretical NO...

Abstract Reaction of benzylpotassium, n , s ‐dibutylmagnesium and diisopropylamine in boiling toluene produces a rare example molecular magnesium hydride with Mg‐(μ‐H) 2 ‐Mg double bridge, [K Mg (N i Pr ) 4 (μ‐H) ·(toluene) ] ( 1 ). In an effort to rationalise the formation series DFT calculations were performed. This report establishes first isostructural pair Na K complexes solvated by be reported Cambridge Crystallographic Database. comparison its previously analogue, metal‐arene centroid...

Abstract Highly active oxygen capable to selectively oxidize methane methanol at low temperature can be prepared in transition-metal cation exchanged zeolites. Here we show that the α -oxygen stabilized by negative charges of two framework aluminum atoms dissociation nitrous oxide over distant binuclear structures (M(II)…M(II), M = cobalt, nickel, and iron) accommodated adjacent 6-rings forming cationic sites ferrierite zeolite. This species is analogous known only for iron In contrast...

Photoreceptors containing the light-oxygen-voltage (LOV) domain elicit biological responses upon excitation of their flavin mononucleotide (FMN) chromophore by blue light. The mechanism and kinetics dark-state recovery are not well understood. Here we incorporated non-canonical amino acid p-cyanophenylalanine (CNF) genetic code expansion technology at 45 positions bacterial transcription factor EL222. Screening light-induced changes in infrared (IR) absorption frequency, electric field...

The ultrafast excited-state dynamics of flavin mononucleotide (FMN) was monitored upon light irradiation by a hybrid experimental/computational approach.

Umdirigiert: Konventionelle Organometallbasen deprotonieren Toluol normalerweise an der Methylposition, was zu resonanzstabilisierten Benzylanionen führt. Doch mit einer neuen Art von Dimetall-Metallierung, Natrium-vermittelten Magnesierung, lässt sich die thermodynamische Deprotonierungsposition in den aromatischen Ring verlegen (siehe Bild).

The first solid-state structures of ortho-sulfonated monoazo dyestuffs are reported and compared to those their para- meta-sulfonated analogues. the 16 Na, K, Cs, Mg, Ca, Sr, Ba salts found have fewer M-O(3)S bonds than isomeric equivalents this in turn means that metal type is no longer prime indicator which structural will be adopted. replaced by M-OH(2), M-HOR M-pi interactions, apparently for steric reasons. As well as new bonding motifs, changed dye shape also leads packing motifs....

Noncovalent complexes of hydrophobic peptides GLLLG and GLLLK with photoleucine (L*) tagged G(L*nLm)K (n = 1,3, m 2,0) were generated as singly charged ions in the gas phase probed by photodissociation at 355 nm. Carbene intermediates produced photodissociative loss N2 from L* diazirine rings underwent insertion into X−H bonds target peptide moiety, forming covalent adducts yields reaching 30%. Gas-phase sequencing revealed preferred bond formation C-terminal residue peptide. Site-selective...

Activation of dioxygen is extreme importance due to its potential for transformation methane valuable products and applications in other selective oxidation reactions. Distant binuclear cationic Fe(II) centers Fe-ferrierite were shown split at room temperature form a pair very active oxygen species (i.e., α-oxygens) subsequently oxidize methanol as well. Our study reveals that the activity splitting represents general property distant stabilized aluminosilicate matrix. Computational models...

Toluene is metallated by DABCO-activated disodium tetrabutylmagnesiate, but not monosodium tributylmagnesiate; this distinction rationalised DFT calculations on model systems, and the crystal structure of main non-metallated product, which shows interstitial MgBu4(2-) dianions within a polycationic network, reported.

Bis(toluene)chromium is regioselectively deprotonated at the para position on one ring only by a mixed sodium−magnesium alkyl bis(amide) TMEDA activated synergic base in reaction influenced Na···π-arene contacts present crystalline trimetallic product.

Abstract The syntheses of the complexes [M(Tm Me )(CO) 2 (NO)] (M = Mo, W) by reaction NOBF 4 with 3 ] – are reported and their spectroscopic characterisation crystal structures described. analogous Cr complex could not be prepared this methodology. adopt expected pseudo‐octahedral geometry. Complexes [M(L)(CO) Cr, W; L Cp, Tp Tm ) together hypothetical [Mo(CO) + cation were subjected to DFT calculations. Geometry‐optimised closely parallel crystallographic determinations indicate that...

We report a gas-phase UV photodissociation study investigating non-covalent interactions between neutral hydrophobic pentapeptides and peptide ions incorporating diazirine-tagged photoleucine residue. Phenylalanine (Phe) proline (Pro) were chosen as the conformation-affecting residues that incorporated into small library of pentapeptides. Gas-phase ion-molecule complexes these peptides with photo-labeled subjected to photodissociation. Selective photocleavage diazirine ring at 355 nm formed...