Pushing the limits of electron donation for -chelating ligands an alliance of phosphonium ylide and anionic abnormal NHC.

The grafting of a -(CH)PR moiety on an NHC ligand backbone in the Mn(I) complex [Cp(CO)Mn(IMes)] followed by double deprotonation opens a route to bidentate ligands with extreme electron-donating character. Such remarkable electronic properties can even allow intramolecular sp C-H functionalization in typically inert square-planar Rh(I) dicarbonyl complexes.

Influence of triphosphine ligand coordination geometry in Mn(I) hydride complexes [(PPP)(CO)MnH] on their kinetic hydricity.

Octahedral Mn(I) complexes bearing tridentate donor ligands [(LL'L'')(CO)MnX] have recently emerged as major players in catalytic (de)hydrogenation processes. While most of these systems are still based on structurally rigid pincer scaffolds imposing a meridional coordination mode, for some more flexible tridentate ligands a facial arrangement of donor moieties becomes possible. Accordingly, the geometry of the corresponding Mn(I) hydrides [(LL'L'')(CO)MnH] directly involved in the catalytic processes, namely the nature of the donor extremity located in the -position of the hydride (CO and L for - and -configurations, respectively) may influence their hydride transfer ability.

Substituents' Effect on the Photophysics of Trinuclear Copper(I) and Silver(I) Pyrazolate-Phosphine Cages.

A series of structurally similar trinuclear macrocyclic copper(I) and silver(I) pyrazolate complexes bearing various short-bite diphosphine RPCH(R')PR ligands are reported. Upon diphosphine coordination, the planar geometry of the initial complexes undergoes bending along the line between two metal atoms coordinated to the phosphorus moieties. The complexes based on dcpm ligands (R = cyclohexyl, R' = H, Ph) do not exhibit dynamic behavior in solution at room temperature on the P NMR time scale as it was previously observed for similar trinuclear copper complexes bearing the dppm (R = Ph, R' = H) scaffold.

Synergism of primary and secondary interactions in a crystalline hydrogen peroxide complex with tin.

Despite the significance of HO-metal adducts in catalysis, materials science and biotechnology, the nature of the interactions between HO and metal cations remains elusive and debatable. This is primarily due to the extremely weak coordinating ability of HO, which poses challenges in characterizing and understanding the specific nature of these interactions. Herein, we present an approach to obtain HO-metal complexes that employs neat HO as both solvent and ligand.

Impact of the Methylene Bridge Substitution in Chelating NHC-Phosphine Mn(I) Catalyst for Ketone Hydrogenation.

Systematic modification of the chelating NHC-phosphine ligand (NHC = N-heterocyclic carbene) in highly efficient ketone hydrogenation Mn(I) catalyst fac-[(PhPCHNHC)Mn(CO)Br] has been performed and the catalytic activity of the resulting complexes was evaluated using acetophenone as a benchmark substrate. While the variation of phosphine and NHC moieties led to inferior results than for a parent system, the incorporation of a phenyl substituent into the ligand methylene bridge improved catalytic performance by ca. 3 times providing maximal TON values in the range of 15000-20000.

Two active species from a single metal halide precursor: a case study of highly productive Mn-catalyzed dehydrogenation of amine-boranes intermolecular bimetallic cooperation.

Metal-metal cooperation for inert bond activation is a ubiquitous concept in coordination chemistry and catalysis. While the great majority of such transformations proceed intramolecular mode in binuclear complexes, to date only a few examples of intermolecular small molecule activation using usually bimetallic frustrated Lewis pairs (M⋯M') have been reported. We introduce herein an alternative approach for the intermolecular bimetallic cooperativity observed in the catalytic dehydrogenation of amine-boranes, in which the concomitant activation of N-H and B-H bonds of the substrate the synergetic action of Lewis acidic (M) and basic hydride (M-H) metal species derived from the same mononuclear complex (M-Br).

Pyrazolate phenylethynide: direct exchange of the anionic bridging ligand in a cyclic trinuclear silver complex.

Cyclic trinuclear Ag(I) pyrazolate interacts with phenylacetylene forming a mix-ligand complex in which one pyrazolate ligand is changed to phenylethynide. The CC fragment coordinates only to two silver(I) atoms one carbon atom demonstrating unique μ-η σ-coordination with close Ag-C bond lengths and Ag-C-C angles. The complex exhibits blue emission under UV irradiation.

Tetranuclear Copper(I) and Silver(I) Pyrazolate Adducts with 1,1'-Dimethyl-2,2'-bibenzimidazole: Influence of Structure on Photophysics.

A reaction of a cyclic trinuclear copper(I) or silver(I) pyrazolate complex ([MPz], M = Cu, Ag) with 1,1'-dimethyl-2,2'-bibenzimidazole () leads to the formation of tetranuclear adducts decorated by one or two molecules of a diimine ligand, depending on the amount of the ligand added (0.75 or 1.5 equivalents).

Versatile Reactivity of Half-Sandwich Rhodium(III) Iminophosphonamide Complexes.

Novel 18e̅ and 16e̅ pentamethylcyclopentadienyl rhodium(III) complexes [(η-CMe)RhX(NPN)] (, X = Cl; , X = PF, BAr) with chelating zwitterionic iminophosphonamide (NPN) ligands (PhP(NR)(NR'); , R = R' = -Tol; , R = -Tol, R' = Me; , R = R' = Me) were synthesized and characterized by single-crystal X-ray diffraction. In the 16e̅ complexes , the rhodium (Rh) atom is efficiently stabilized by π-donation of unshared N electrons, thus hampering coordination of the external ligands and rendering the 18e̅ complexes labile. Due to low coordination enthalpy, the cationic 18e̅ monocarbonyl and pyridine adducts are stable only at low temperatures.

[Clinical guidelines «Polycystic Ovary Syndrome»].

Polycystic ovary syndrome (PCOS) is a polygenic endocrine disorder caused by both genetic and epigenetic factors. Depending on the period of a woman's life, the clinical picture, diagnosis, and treatment tactics of the disease are different. PCOS has a complex of reproductive, metabolic and psychological characteristics.

-to- isomerization triggers hydride transfer from Mn(I) complex -[(dppm)Mn(CO)H].

Low-temperature IR and NMR studies combined with DFT calculations revealed the mechanistic complexity of apparently simple reactions between Mn(I) complex -[(dppm)Mn(CO)H] and Lewis acids (LA = PhC, B(CF)) involving the formation of so-far elusive meridional hydride species -[(dppm)Mn(CO)H⋯LA] and unusual dearomatization of the PhC cation upon hydride transfer.

Amine-boranes reactions promoted by lanthanide(II) ions.

The catalytic activity in amine-borane dehydrogenation is shown for the first time for Ln(II) species using complexes [{(Bu-CH)CH}M·L] (M = Yb, Sm, L = (DME), TMEDA). The protonation of M(II)-C bonds with HNRRBH affords amidoborane complexes [M(NRRBH)L], which under excess HNMeBH transform to [NMeBHNMeBH] derivatives, both serving as the dehydrocoupling intermediates.

Mononuclear Copper(I) 3-(2-pyridyl)pyrazole Complexes: The Crucial Role of Phosphine on Photoluminescence.

A series of emissive Cu(I) cationic complexes with 3-(2-pyridyl)-5-phenyl-pyrazole and various phosphines: dppbz (), Xantphos (), DPEPhos (), PPh (), and BINAP () were designed and characterized. Complexes obtained exhibit bright yellow-green emission (ca. 520-650 nm) in the solid state with a wide range of QYs (1-78%) and lifetimes (19-119 µs) at 298 K.

Lossen rearrangement by Rh(III)-catalyzed C-H activation/annulation of aryl hydroxamates with alkynes: access to quinolone-containing amino acid derivatives.

A convenient and robust method for the preparation of new CF-containing 2-quinolones has been developed a Rh(III)-catalyzed C-H activation/Lossen rearrangement/annulation cascade of -pivaloyloxy-arylamides with internal alkynes bearing an α-CF-α-amino acid moiety on the triple bond. This work expands the scope of valuable products that are available through C-H activation/annulation reactions of arylamides in organic synthesis.

The Reaction of Hydrogen Halides with Tetrahydroborate Anion and Hexahydro--hexaborate Dianion.

The mechanism of the consecutive halogenation of the tetrahydroborate anion [BH] by hydrogen halides (HX, X = F, Cl, Br) and hexahydro--hexaborate dianion [BH] by HCl via electrophile-induced nucleophilic substitution (EINS) was established by ab initio DFT calculations [M06/6-311++G(d,p) and wB97XD/6-311++G(d,p)] in acetonitrile (MeCN), taking into account non-specific solvent effects (SMD model). Successive substitution of H by X resulted in increased electron deficiency of borohydrides and changes in the character of boron atoms from nucleophilic to highly electrophilic. This, in turn, increased the tendency of the B-H bond to transfer a proton rather than a hydride ion.

Bifunctional activation of amine-boranes by the W/Pd bimetallic analogs of "frustrated Lewis pairs".

The reaction between basic [(PCP)Pd(H)] (PCP = 2,6-(CHP(-CH))CH) and acidic [LWH(CO)] (L = Cp (), Tp (); Cp = η-cyclopentadienyl, Tp = κ-hydridotris(pyrazolyl)borate) leads to the formation of bimolecular complexes [LW(CO)(μ-CO)⋯Pd(PCP)] (, ), which catalyze amine-borane (MeNHBH, BuNHBH) dehydrogenation. The combination of variable-temperature (H, P{H}, B NMR and IR) spectroscopies and computational (ωB97XD/def2-TZVP) studies reveal the formation of an η-borane complex [(PCP)Pd(MeNHBH)][LW(CO)] () in the first step, where a BH bond strongly binds palladium and an amine group is hydrogen-bonded to tungsten. The subsequent intracomplex proton transfer is the rate-determining step, followed by an almost barrierless hydride transfer.

Synthesis of Bis(Carboranyl)amides 1,1'-μ-(CHNH(O)C(CH)-1,2-CBH) ( = 0, 1) and Attempt of Synthesis of Gadolinium Bis(Dicarbollide).

Bis(carboranyl)amides 1,1'-μ-(CHNH(O)C(CH)-1,2-CBH) ( = 0, 1) were prepared by the reactions of the corresponding carboranyl acyl chlorides with ethylenediamine. Crystal molecular structure of 1,1'-μ-(CHNH(O)C-1,2-CBH) was determined by single crystal X-ray diffraction. Treatment of bis(carboranyl)amides 1,1'-μ-(CHNH(O)C(CH)-1,2-CBH) with ammonium or cesium fluoride results in partial deboronation of the -carborane cages to the -carborane ones with formation of [7,7'(8')-μ-(CHNH(O)C(CH)-7,8-CBH)].

Experimental and Theoretical Insights into the Electronic Properties of Anionic N-Heterocyclic Dicarbenes through the Rational Synthesis of Their Transition Metal Complexes.

The lithiation of the NHC ligand backbone in Cp(CO)Mn(IMes) followed by transmetalation on the C4 carbenic position with Cp(CO)FeI led to the heterobimetallic complex Cp(CO)Mn(IMes)Fe(CO)Cp bearing the anionic ditopic imidazol-2,4-diylidene IMes ligand. Subsequent treatment of the later with TfOH induced a selective decoordination of the [Cp(CO)Mn] fragment to form the cationic abnormal NHC complex [Cp(CO)Fe(IMes)](OTf), which was further derivatized to the bis(iron) IMes complex [Cp(CO)Fe(IMes)Fe(CO)Cp](OTf) by reaction with AmOK and Cp(CO)FeI. The effect of the metalation at the C4 or C2 position on the imidazole ring on the electronic donation properties of the associated C2 and C4 carbenic centers in the IMes ligand was quantified through systematic experimental and theoretical studies of IMes, IMes, and IMes complexes.

The unexpected reactivity of 9-iodo-nido-carborane: from nucleophilic substitution reactions to the synthesis of tricobalt tris(dicarbollide) Na[4,4',4''-(MeOCHCHO)-3,3',3''-Co(μ-O)(μ-S)(1,2-CBH)].

An unusual reactivity of 9-iodo-nido-carborane [9-I-7,8-CBH] towards nucleophiles under strong basic conditions was revealed. The nucleophilic substitution of iodine with O- and N-nucleophiles results in [9-RO-7,8-CBH] (R = H, CHCHOMe) and [9-L-7,8-CBH] (L = Py, NEt, MeNCHCHNMe), respectively. Reaction of [9-I-7,8-CBH] with CoCl in 1,2-dimethoxyethane in the presence of t-BuOK, depending on the order of addition of the reagents, leads either to a diastereomeric mixture of diiodo derivatives cobalt bis(dicarbollide) rac-[4,4'-I-3,3'-Co(1,2-CBH)] and meso-[4,7'-I-3,3'-Co(1,2-CBH)] or to the corresponding mixture of 2-methoxyethoxy derivatives rac-[4,4'-(MeOCHCHO)-3,3'-Co(1,2-CBH)] and meso-[4,7'-(MeOCHCHO)-3,3'-Co(1,2-CBH)].

Perinatal outcomes in pregnant women with COVID-19 in Siberia and the Russian Far East.

Objective: To assess the incidence and perinatal outcomes of COVID-19 in pregnant women in the Far Eastern and Siberian Federal Districts of Russian Federation over 10 months of a pandemic.

Materials And Methods: This was secondary analysis of Public Data basis on 25 Dec 2020. Statistics included descriptive statistics, analysis of contingency tables, which assessed the value of , the achieved significance level ().

Stereoisomerism as an Origin of Different Reactivities of Ir(III) PC(sp)P Pincer Catalysts.

Two stereoisomers of pentacoordinate iridium(III) hydridochloride with triptycene-based PC(sp)P pincer ligand (1,8-bis(diisopropylphosphino)triptycene), and , differ by the orientation of hydride ligand relative to the bridgehead ring of triptycene. According to DFT/B3PW91/def2-TZVP calculations performed, an equatorial Cl ligand can relatively easily change its position in , whereas that is not the case in . Both complexes and readily bind the sixth ligand to protect the empty coordination site.

Dichotomous Si-H Bond Activation by Alkoxide and Alcohol in Base-Catalyzed Dehydrocoupling of Silanes.

The activation of silanes in dehydrogenative coupling with alcohols under general base catalysis was studied experimentally (using multinuclear NMR, IR, and UV-visible spectroscopies) and computationally (at DFT M06/6-311++G(d,p) theory level) on the example of PhSiH ( = 1-3) interaction with (CF)CHOH in the presence of EtN. The effect of the phenyl groups' number and H substitution by the electron-withdrawing (CF)CHO group on Si-H bond hydricity (quantified as hydride-donating ability, HDA) and Lewis acidity of silicon atom (characterized by maxima of molecular electrostatic potential) was accessed. Our results show the coordination of Lewis base (Y = MeN, ROH, OR) leads to the increased hydricity of pentacoordinate hypervalent PhSi(Y)H complexes and a decrease of the reaction barrier for H release.

Thermodynamic Hydricity of Small Borane Clusters and Polyhedral -Boranes.

Thermodynamic hydricity (HDA) determined as Gibbs free energy (ΔG°[H]) of the H detachment reaction in acetonitrile (MeCN) was assessed for 144 small borane clusters (up to 5 boron atoms), polyhedral -boranes dianions [BH], and their lithium salts Li[BH] (n = 5-17) by DFT method [M06/6-311++G(d,p)] taking into account non-specific solvent effect (SMD model). Thermodynamic hydricity values of diborane BH (HDA = 82.1 kcal/mol) and its dianion [BH] (HDA = 40.

Steric and Electronic Effect of Cp-Substituents on the Structure of the Ruthenocene Based Pincer Palladium Borohydrides.

Ruthenocene-based PCP pincer ligands were used to synthesize novel pincer palladium chloride Rc[PCP]PdCl () and two novel palladium tetrahydroborates Rc[PCP]Pd(BH) () and Rc[PCP]Pd(BH) (), where Rc[PCP] = κ-{2,5-(tBuPCH)CH}Ru(Cp) (Cp = CMeCF), and Rc*[PCP] = κ-{2,5-(tBuPCH)CH}Ru(Cp*) (Cp* = CMe). These coordination compounds were characterized by X-ray, NMR and FTIR techniques. Analysis of the X-ray data shows that an increase of the steric bulk of non-metalated cyclopentadienyl ring in and relative to non-substituted Rc[PCP]Pd(BH) analogue (; where Rc[PCP] = κ-{2,5-(tBuPCH)CH}Ru(Cp), Cp = CH) pushes palladium atom from the middle plane of the metalated Cp ring in the direction opposite to the ruthenium atom.