Florian Winter

Stannylium Ions, a Tin(II) Arene Complex, and a Tin Dication Stabilized by Weakly Coordinating Anions

The reactivity of aryl-substituted stannylenes, Ar(2)Sn (4), towards silylarenium borates, [R(3)SiArH][B(C(6)F(5))(4)] (3), was investigated. The reaction with 2,3,4-trimethyl-6-tert-butylphenyl (mebp)-substituted stannylene gave silyl-substituted stannylium ions 2a,b, which were characterized by NMR spectroscopy supported by the results of quantum-mechanical computations of molecular structures and magnetic properties. The tri-iso-propylphenyl-substituted stannylium ions 2c,d undergo a decomposition reaction in toluene to give the dicationic tin-arene complex [Sn(C(7)H(8))(3)](2+) (5) in the form of the [B(C(6)F(5))(4)] salt in high yields. The 5[B(C(6)F(5))(4)](2) salt was identified by single crystal X-ray diffraction analysis and by Mössbauer spectroscopy. The bonding situation was investigated by using natural bond orbital (NBO) and quantum theory of atoms in molecules (QTAIM) calculations. The substitution of the weakly coordinating borate anion by the carboranate [CB(11)H(6)Br(6)](-) results in replacement of the toluene ligands and formation of tin(II) carboranate with only weak Sn(2+)-anion interactions as suggested by the solid-state structure of the isolated salt.

{Sn9[Si(SiMe3)3]2}2-: a metalloid tin cluster compound with a Sn9 core of oxidation state zero.

The disproportionation reaction of the subvalent metastable halide SnCl proved to be a powerful synthetic method for the synthesis of metalloid cluster compounds of tin. Now we present the synthesis and structural characterization of the anionic metalloid cluster compound [Sn(9)[Si(SiMe(3))(3)](2)](2-)3 where the oxidation state of the tin atoms is zero. Quantum chemical calculations as well as Mössbauer spectroscopic investigations show that three different kinds of tin atoms are present within the cluster core. Compound 3 is highly reactive as shown by NMR investigations, thus being a good starting material for further ongoing research on the reactivity of such partly shielded metalloid cluster compounds.

Synthesis and characterization of N-[2-P(i-Pr)2-4-methylphenyl]2- (PNP) pincer tin(IV) and tin(II) complexes.

N-[2-P(i-Pr)(2)-4-methylphenyl](2)(-) (PNP) pincer complexes of tin(IV) and tin(II), [(PNP)SnCl(3)] (2) and [(PNP)SnN(SiMe(3))(2)] (3), respectively, were prepared and characterized by X-ray diffraction, solution and solid state NMR spectroscopy, and (119)Sn Mössbauer spectroscopy. Furthermore, (119)Sn cross polarization magic angle spinning NMR spectroscopic data of [Sn(NMe(2))(2)](2) are reported. Compound 2 is surprisingly stable toward air, but attempts to substitute chloride ligands caused decomposition.

Fe-Doped ZnO Nanoparticles: The Oxidation Number and Local Charge on Iron, Studied by 57Fe Mößbauer Spectroscopy and DFT Calculations

Iron bru: Fe-doped ZnO may contain Fe(2+) and Fe(3+) species. Whilst Mößbauer spectroscopy can distinguish these sites in pure oxides FeO and Fe(2)O(3), it gives very similar shifts for Fe-doped phases. This result is rationalized by electron redistribution from the dopant site to the crystal matrix. Mößbauer shifts correlate with the local charge on the Fe sites and different dopant sites can be identified by the Mößbauer quadrupole splitting (see figure).

{Sn10 [Si(SiMe3 )3 ]4 }(2-) : A highly reactive metalloid tin cluster with an open ligand shell.

The reaction of a Sn(I) Cl solution with LiSi(SiMe3 )3 gave the anionic metalloid tin cluster {Sn10 [Si(SiMe3 )3 ]4 }(2-) (7) in good yield. The arrangement of the ten tin atoms in the cluster core can be described as a distorted centaur polyhedron. Quantum chemical calculations suggest that there are 26 bonding electrons in the cluster core, which may be described as an arachno cluster in agreement with Wades rules. NMR and mass spectrometric investigations showed that 7 is highly reactive, which may be due to the open ligand shell. The easily available tin atoms in 7 thereby open the door to further subsequent reactions, in which 7 may act as a building block to larger cluster aggregates.

An investigation of the electrochemical delithiation process of carbon coated α-Fe2O3 nanoparticles

The electrochemical lithiation–delithiation of iron oxide is a rather complex process, which is still not fully understood. In this study we investigated the electrochemical lithiation–delithiation mechanism of hematite by means of X-ray diffraction (XRD), 57Fe Mossbauer spectroscopy, high-resolution transmission electron microscopy (HRTEM) and X-ray absorption spectroscopy (XAS). Since the delithiation process has been so far less investigated, particular attention was dedicated to the characterization of the chemical species that are formed during this process. The results of this investigation indicated that at the end of the delithiation process lithium iron oxide α-LiFeO2 is formed. The formation of this compound may be the explanation for the irreversible capacity loss in the first cycle, which is usually assigned to the formation of an organic gel-like layer. Based on these results a new charge–discharge mechanism of hematite in lithium-ion batteries (LIBs) is proposed and discussed.

Ionic Pathways in Li13Si4 investigated by 6Li and 7Li solid state NMR experiments

Local environments and dynamics of lithium ions in the binary lithium silicide Li13Si4 have been studied by (6)Li MAS-NMR, (7)Li spin-lattice relaxation time and site-resolved (7)Li 2D exchange NMR measurements as a function of mixing time. Variable temperature experiments result in distinct differences in activation energies characterizing the transfer rates between the different lithium sites. Based on this information, a comprehensive picture of the preferred ionic transfer pathways in this silicide has been developed. With respect to local mobility, the results of the present study suggests the ordering Li6/Li7>Li5>Li1>Li4 >Li2/Li3. Mobility within the z=0.5 plane is distinctly higher than within the z=0 plane, and the ionic transfer between the planes is most facile via Li1/Li5 exchange. The lithium ionic mobility can be rationalized on the basis of the type of the coordinating silicide anions and the lithium-lithium distances within the structure. Lithium ions strongly interacting with the isolated Si(4-) anions have distinctly lower mobility than those the coordination of which is dominated by Si2(6-) dumbbells.

[{Fe(CO)3}4{SnI}6I4]2−: The First Bimetallic Adamantane‐Like Cluster

Show some metal: the first bimetallic adamantane-like cluster, [{Fe(CO)(3)}(4){SnI}(6)I(4)](2-), was prepared by an ionic-liquid-based synthesis. The valence states of iron and tin were verified based on bond-length considerations, FT-IR and (119)Sn Mössbauer spectroscopy, as well as with DFT calculations.

Rational Syntheses and Serendipity: Complexes [LSnPtCl2(SMe2)]2, [{LSnPtCl(SMe2)}2SnCl2], [(LSn)3(PtCl2)(PtClSnCl){LSn(Cl)OH}], and [O(SnCl)2(SnL)2] with L=MeN(CH2CMe2O)2

Syntheses and molecular structures of the dimeric tin-platinum complex [LSnPtCl2 (SMe2 )]2 (2), the tin-platinum clusters [{LSnPtCl(SMe2 )}2 SnCl2 )] (3) and [(LSn)3 (PtCl2 )(PtClSnCl)(LSnOHCl)] (6) (L=MeN(CH2 CMe2 O- )2 ), and of the unprecedented tin(II) aminoalkoxide-tin oxide chloride complex [O(SnCl)2 ⋅(SnL)2 ] (5) are reported. The compounds were characterized by NMR spectroscopy (1 H, 13 C, 119 Sn, 195 Pt), 119 Sn Mössbauer spectroscopy (1-3, 6), electrospray ionization mass spectrometry, elemental analyses, and single-crystal X-ray diffraction analyses (2⋅CH2 Cl2 , 3⋅2 C4 H8 O, 5, 6⋅3CH2 Cl2 ). The tin(II) aminoalkoxide [MeN(CH2 CMe2 O)2 Sn]2 (1) behaves like a neutral ligand, inserts into a Pt-Cl bond, or is involved in rearrangement reactions with the different behavior occurring even within one compound (3, 6). DFT calculations show that the tin-platinum compounds behave like electronic chameleons.

Lithium transition metal pnictides – structural chemistry, electrochemistry, and function

Abstract Lithium-transition metal (T)-pnictides (Pn=P, As, Sb, Bi) are an interesting class of materials with greatly differing crystal structures. The transition metal and pnictide atoms build up covalently bonded networks that leave cavities or channels for the lithium atoms. Depending on the bonding of lithium to the polyanionic network, one observes mobility of the lithium atoms. The crystal chemistry, chemical bonding, 7Li solid-state NMR, and the electrochemical behavior of the pnictides are reviewed. The structural chemistry is compared with related tetrelides.