Zur Elektronenstruktur metallorganischer Komplexe der f‐Elemente. 67 Erstmalige parametrische Analyse des Absorptionsspektrums einer Molekülverbindung des CeIIIμ: Tris(η5‐tetramethylcyclopentadienyl)cer

Electronic Structures of Organometallic Complexes of f Elements. 67 First Parametric Analysis of the Absorption Spectrum of a Molecular Compound of Ce^IIIμ: Tris(η⁵‐tetramethylcyclopentadienyl)cerium(III) The absorption spectra (in the IR/NIR/Vis/UV range) of Ce(C₅Me₄H)₃ ( 1 ) and La(C₅Me₄H)₃ ( 2 ) were recorded at room and low temperatures. From the spectra obtained, two alternative closely related crystal field (CF) splitting patterns of 1 could be derived, and simulated by fitting the free parameters of a phenomenological Hamiltonian. The fact that the difference of the experimental energies of the barycenters of CF levels of the multiplets ²F_7/2 and ²F_5/2 is larger than in the gaseous free Ce³⁺ ion (“anti”‐relativistic nephelauxetic effect) could be explained by coupling effects of these multiplets via the CF, resulting in lower spin‐orbit coupling parameters than in the case of the gaseous free Ce³⁺ ion. The experimentally derived CF splitting pattern of 1 is compared with the predictions of previous non‐relativistic SW‐Xα and relativistic DV‐Xα calculations.     

Zur Elektronenstruktur metallorganischer Komplexe der f‐Elemente. 60 [1] Strukturelle,einkristalloptische und magnetooptische Untersuchungen von Trialkylphosphat‐Addukten des Grundkörpers Tris(cyclopentadienyl)lanthanid(III) (Ln = La,Pr) sowie Ergebnisse vergleichender optischer Studien an [Pr(Ind)3(OP(OEt)3)] (Ind = Indenyl)

Electronic Structures of Organometallic Complexes of f Elements. 60 [1] Structural, Single Crystal Optical and Magnetooptical Investigations on Trialkylphosphate Adducts of the Tris(cyclopentadienyl)lanthanide(III) (Ln = La, Pr) Moiety as well as Results of Comparing Optical Studies of [Pr(Ind)₃(OP(OEt)₃)] (Ind = indenyl) [Ln(Cp)₃(OP(OR)₃)] (Cp = η⁵‐cyclopentadienyl; Ln = La, R = Et ( 1 ); Ln = Pr, R = Me ( 2 ); Ln = Pr, R = Et ( 3 )) and [Pr(Ind)₃(OP(OEt)₃)] ( 4 ) have been synthesized and spectroscopically as well as partly structurally (only compounds 1 and 2 ) characterized. On the basis of variable temperature measurements of α absorption spectra of an oriented single crystal, the magnetic circular dichroism spectra of dissolved, and the luminescence spectra of powdered material, a nearly complete crystal field (CF) splitting pattern could be derived for 3 , and simulated by fitting the free parameters of a phenomenological Hamiltonian. The parameters used in the fit allowed the calculation of the global CF strength experienced by the Pr³⁺ central ion, the estimation of the nephelauxetic and relativistic nephelauxetic parameters, as well as the setup of experimentally based non‐relativistic and relativistic molecular orbital schemes in the f range. The optical spectra of compound 4 suggest that two different species exist at low temperatures, thus preventing a successful CF analysis.     

Zur Elektronenstruktur metallorganischer Komplexe der f‐Elemente. 65 Erstmalige Beobachtung des linearen Dichroismus bei einem homoleptischen metallorganischen π‐Komplex der f‐Elemente: Tris(η5‐tetramethylcyclopenta‐dienyl)neodym(III)

Electronic Structures of Organometallic Complexes of f Elements. 65 First Observation of Linear Dichroism of a Homoleptic Organometallic π Complex of f Elements: Tris(η⁵‐tetramethylcyclopentadienyl)neodymium(III) The absorption spectrum of a powder sample of pseudo (Ψ) trigonal planar Nd(η⁵‐C₅Me₄H)₃ ( 1 ) has been measured at room temperature and ca. 40 K, respectively, and the linear dichroism spectra of σ‐ and π‐type of an oriented single crystal at ambient temperature and 77 K. Neglecting the signals of the C–H combination vibrations and overtones extracted from the absorption spectrum of La(η⁵‐C₅Me₄H)₃ ( 2 ), the observed polarization properties of the remaining f‐f transitions allowed the derivation of a truncated crystal field splitting pattern. The free parameters of a phenomenological Hamiltonian were fitted to this pattern leading to a reduced r.m.s. deviation of 16.1 cm^?1 for 38 assignments. The temperature dependence of the paramagnetic susceptibility of 1 was calculated, making use of the crystal field energies and wavefunctions of the fit. Introducing an orbital reduction factor of 0.98, calculated values of 1 agree well with the experimental ones of Ψ trigonal planar Nd(C₅H₄tBu)₃.     

Zur Elektronenstruktur metallorganischer Komplexe der f‐Elemente. 64 Äußert sich die zwitterionische Natur des Triphenylphosphanoxid‐Liganden auch in seinen spektrochemischen Eigenschaften?

Electronic Structures of Organometallic Compounds of f Elements. 64 Does the Zwitterionic Nature of the Triphenylphosphine Oxide Ligand Manifest itself in its Spectrochemical Properties? The triphenylphosphine oxide mono adducts of the moiety tris(η⁵‐cyclopentadienyl)lanthanide(III) (Ln(Cp)₃; Ln = Pr ( 1 ), La ( 2 )) were synthesized and structurally characterized. The Ln–O distances of these compounds are noticeably shorter than those of the corresponding THF adducts. A crystal field (CF) analysis of the optical spectra of 1 leads to a low absolute value of the quadratic CF parameter which is comparable with those of [Pr(Cp)₃(L)]^? adducts with anionic bases but not with [Pr(Cp)₃(MeTHF)]. Reasons for the latter finding are presented.     

Spektroskopische und strukturelle Charakterisierung von Tris(2, 6‐di‐t‐butyl‐phenolato)lanthanid(III) (Ln(OAr′)3; Ln = Pr,Nd) sowie parametrische Analyse des Kristallfeld‐Aufspaltungsmusters von Nd(OAr′)3

Electronic Structures of Highly Symmetrical Compounds of f Elements. 37 [1] Spectroscopic and Structural Characterization of Tris(2, 6‐di‐t‐butyl‐phenolato)lanthanide(III) (Ln(OAr′)₃; Ln = Pr, Nd), and Parametric Analysis of the Crystal Field Splitting Pattern of Nd(OAr′)₃ Pr(OAr′)₃ and Nd(OAr′)₃ crystallize (at approximately 150 K and 200 K, respectively) in the monoclinic space group P2₁ with four molecules in the unit cell. If one considers only the directly coordinating oxygen atoms, the effective crystal field is of C_3v symmetry. The signals in the optical spectra of Pr(OAr′)₃ are broad using either solutions or solids, even at ca. 80‐90 K, thus they are not suitable for interpretation purposes. Nd(OAr′)_3, however, exhibits sharp absorption bands at room and low temperatures, which are assigned in analogy to the previously identified absorption transitions of Nd[N(SiMe₃)₂]₃ based on optical polarization measurements. The thus derived crystal field splitting pattern is simulated by fitting the free parameters of a phenomenological Hamiltonian, achieving a reduced r.m.s. deviation of 26.4 cm^—1 for 64 assignments. The parameters used allow the estimation of the ligand field strength associated with the (OAr′)^— ligand, the insertion of this ligand into empirical nephelauxetic and relativistic nephelauxetic series, and the setup of experimentally‐based non‐relativistic and relativistic molecular orbital schemes in the f range.     

Zur Elektronenstruktur hochsymmetrischer Verbindungen der f‐Elemente. 38 [1] Kristall‐, Molekül‐ und Elektronenstruktur von Tris(hydrotris(1‐pyrazolyl)borato)‐samarium(III)

Electronic Structures of Highly Symmetrical Compounds of f Elements. 38 [1] Crystal, Molecular and Electronic Structure of Tris(hydrotris(1‐pyrazolyl)borato)samarium(III) Tris(hydrotris(1‐pyrazolyl)borato)samarium(III) (SmTp₃) crystallizes in the space group P6₃/m (No. 176) with two molecules in the unit cell. The Sm³⁺ central ion is coordinated by nine N atoms in the shape of a tricapped trigonal prism, leading to an effective crystal field (CF) of D_3h symmetry. The underlying CF splitting pattern was extracted from the absorption and luminescence spectra run at room and low temperatures, and simulated by fitting the free parameters of a phenomenological Hamiltonian achieving an r.m.s. deviation of 9.4 cm^?1 for 58 assignments. The parameters used allow the estimation of the global ligand field strength experienced by the Sm³⁺ central ion, the insertion of SmTp₃ into empirical nephelauxetic and relativistic nephelauxetic series, and the set‐up of experimentally based nonrelativistic and relativistic molecular orbital schemes in the f range.     

Electronic structures of organometallic complexes of f elements LXVI : Parametric analysis of the linear dichroism spectrum of an oriented tris(η-tetramethylcyclopentadienyl)samarium(III) single crystal

The absorption spectra of pseudo (ψ) trigonal planar Sm(η⁵-C₅Me₄H)₃ (1) and La(η⁵-C₅Me₄H)₃ (2) in KBr pellets have been measured at room temperature and 77 K, respectively. Additionally, the linear dichroism spectra of σ and π type of an oriented single crystal of 1 have been recorded at ambient temperature. The observed polarization properties of the f-f transitions allowed the assignment of the transitions. The free parameters of a phenomenological Hamiltonian were fitted to the energies of the assigned terminal levels, leading to a reduced r.m.s. deviation of 19.1 cm⁻¹ for 19 assignments. On the basis of these phenomenological CF parameters, the global CF strength experienced by the Sm³⁺ central ion was estimated, and seems to be the largest one ever encountered in samarium(III) chemistry. The obtained Slater parameter F² and the spin-orbit coupling parameter ζ_4f allow the insertion of compound 1 into empirical nephelauxetic and relativistic nephelauxetic series, respectively. On the basis of these models, complex 1 turns out to be the most covalent Sm^III compound found to date. The experimentally-based non-relativistic molecular orbital scheme (in the f range) of complex 1 was determined and compared with the results of a previous Xα-SW calculation on the ψ trigonal planar model compound Sm(η⁵-C₅H₅)₃.     

Zur Elektronenstruktur hochsymmetrischer Verbindungen der f‐Elemente. 36 [1] Parametrische Analyse der optischen Spektren eines orientierten Tris(hydrotris(1‐pyrazolyl)borato)praseodym(III)‐Einkristalls

Electronic Structures of Highly Symmetrical Compounds of f Elements. 36 [1] Parametric Analysis of the Optical Spectra of an Oriented Tris(hydrotris(1‐pyrazolyl)borato)praseodymium(III) Single Crystal The absorption and luminescence spectra of polycrystalline tris(hydrotris(1‐pyrazolyl)borato)‐praseodymium(III) (PrTp₃) were measured at room temperature as well as at low temperatures. At room temperature the “polarized” luminescence spectra of a small oriented PrTp₃ single crystal could also be recorded. On the basis of these spectroscopic findings the underlying crystal field splitting pattern could be derived, and simulated by fitting the free parameters of a phenomenological Hamiltonian, achieving a reduced r.m.s. deviation of 17.3 cm^—1 for 37 assignments. On the basis of the parameters used, the global ligand field strength experienced by the Pr³⁺ central ion as well as the individual ligand field strength associated with one Tp ligand are determined, nephelauxetic and relativistic nephelauxetic effects are estimated, and the experimentally orientiented nonrelativistic and relativistic molecular orbital schemes in the f range are set up.     

Activation of SO2 with [(η5‐C5Me5)2Ln(THF)2] (Ln=Eu,Yb) Leading to Dithionite and Sulfinate Complexes

The reaction of decamethylytterbocene [(η⁵‐C₅Me₅)₂Yb(THF)₂] with SO₂ at low temperature gave two new compounds, namely, the Yb^III dithionite/sulfinate complex [{(η⁵‐C₅Me₅)₂Yb(μ₃,1κ²O^1,3,2κ³O^2,2′,4‐S₂O₄)}₂{(η⁵‐C₅Me₅)Yb(μ,1κO,2κO′‐C₅Me₅SO₂)}₂] ( 1 ) and the Yb^III dithionite complex [{(η⁵‐C₅Me₅)₂Yb}₂(μ,1κ²O^1,3,2κ²O^2,4‐S₂O₄)] ( 2 ). After extraction of 1 , the mixture was heated to give the dinuclear tetrasulfinate complex [{(η⁵‐C₅Me₅)Yb}₂(μ,κO,κO’‐C₅Me₅SO₂)₄] ( 3 a ). In contrast, from the reaction of [(η⁵‐C₅Me₅)₂Eu(THF)₂] with SO₂ only the tetrasulfinate complex [{(η⁵‐C₅Me₅)Eu}₂(μ,κO,κO’‐C₅Me₅SO₂)₄] ( 3 b ) was isolated. Two major reaction pathways were observed: 1) reductive coupling of two SO₂ molecules to form the dithionite anion S₂O₄^2?; and 2) nucleophilic attack of one metallocene C₅Me₅ ligand on the sulfur atom of SO₂. The compounds presented are the first dithionite and sulfinate complexes of the f‐elements.     

Die konjugative Verbrückung metallorganischer Reaktionszentren in Heterozweikernkomplexen [(OC)3ClRe(μ‐L)MCl(C5Me5)]+, M = Rh oder Ir ‐ Spektroskopische Konsequenzen reduktiver Aktivierung

The Conjugative Bridging of Organometallic Reaction Centers in Heterodinuclear Complexes [(OC)₃ClRe(μ‐L)MCl(C₅Me₅)]⁺, M = Rh or Ir ‐ Spectroscopic Consequences of Reductive Activation Heterodinuclear complexes [(OC)₃ClRe(μ‐L)MCl(C₅Me₅)](PF₆), M = Rh or Ir and L = 2, 5‐bis(1‐phenyliminoethyl)pyrazine (bpip), 3, 6‐bis(2‐pyridyl)‐1, 2, 4, 5‐tetrazine (bptz) or 2, 2′‐bipyrimidine (bpym), were synthesized via mononuclear rhenium compounds (L)Re(CO)₃Cl. The stepwise reductive activation under chloride dissociation was studied through cyclic voltammetry and spectroelectrochemistry in the range of CO stretching vibrations (IR), charge transfer absorptions (UV/Vis) and electron spin resonance (ESR) for paramagnetic intermediates of the mono‐ and heterodinuclear compounds. While complexes of bpip and bptz form one‐electron reduced radical intermediates [(OC)₃ClRe(μ‐L)MCl(C₅Me₅)] ^˙ , the compounds with bpym react under MCl‐dissociative two‐electron reduction directly to [(OC)₃ClRe(μ‐L)M(C₅Me₅)].     

CH Bond Activation by f‐Block Complexes

Most homogeneous catalysis relies on the design of metal complexes to trap and convert substrates or small molecules to value‐added products. Organometallic lanthanide compounds first gave a tantalizing glimpse of their potential for catalytic C? H bond transformations with the selective cleavage of one C? H bond in methane by bis(permethylcyclopentadienyl)lanthanide methyl [(η⁵‐C₅Me₅)₂Ln(CH₃)] complexes some 25 years ago. Since then, numerous metal complexes from across the periodic table have been shown to selectively activate hydrocarbon C? H bonds, but the challenges of closing catalytic cycles still remain; many f‐block complexes show great potential in this important area of chemistry.     

Stabilization of a Silaaldehyde by its η2 Coordination to Tungsten

Treatment of pyridine‐stabilized silylene complexes [(η⁵‐C₅Me₄R)(CO)₂(H)W?SiH(py)(Tsi)] (R=Me, Et; py=pyridine; Tsi=C(SiMe₃)₃) with an N‐heterocyclic carbene ^MeIⁱPr (1,3‐diisopropyl‐4,5‐dimethylimidazol‐2‐ylidene) caused deprotonation to afford anionic silylene complexes [(η⁵‐C₅Me₄R)(CO)₂W?SiH(Tsi)][H^MeIⁱPr] (R=Me ( 1‐Me ); R=Et ( 1‐Et )). Subsequent oxidation of 1‐Me and 1‐Et with pyridine‐N‐oxide (1 equiv) gave anionic η²‐silaaldehydetungsten complexes [(η⁵‐C₅Me₄R)(CO)₂W{η²‐O?SiH(Tsi)}][H^MeIⁱPr] (R=Me ( 2‐Me ); R=Et ( 2‐Et )). The formation of an unprecedented W‐Si‐O three‐membered ring was confirmed by X‐ray crystal structure analysis.     

Bis(β‐diketiminato) lanthanide amides: synthesis,structure and catalysis for the polymerization of l‐lactide and ε‐caprolactone

Treatment of the chlorides (L^2,6‐iPr2_Ph)₂LnCl (L^2,6‐iPr2_Ph = [(2,6‐ⁱPr₂C₆H₃)NC(Me)CHC(Me)N(C₆H₅)]^?) with 1 equiv. of NaNH(2,6‐ⁱPr₂C₆H₃) afforded the monoamides (L^2,6‐iPr2_Ph)₂LnNH(2,6‐ⁱPr₂C₆H₃) (Ln = Y ( 1 ), Yb ( 2 )) in good yields. Anhydrous LnCl₃ reacted with 2 equiv. of NaL^2,6‐iPr2_Ph in THF, followed by treatment with 1 equiv. of NaNH(2,6‐ⁱPr₂C₆H₃), giving the analogues (L^2,6‐iPr2_Ph)₂LnNH(2,6‐ⁱPr₂C₆H₃) (Ln = Sm ( 3 ), Nd ( 4 )). Two monoamido complexes stabilized by two L^2‐Me ligands, (L^2‐Me)₂LnNH(2,6‐ⁱPr₂C₆H₃) (L^2‐Me = [N(2‐MeC₆H₄)C(Me)]₂CH)^?; Ln = Y ( 5 ), Yb ( 6 )), were also synthesized by the latter route. Complexes 1 , 2 , 3 , 4 , 5 , 6 were fully characterized, including X‐ray crystal structure analyses. Complexes 1 , 2 , 3 , 4 , 5 , 6 are isostructural. The central metal in each complex is ligated by two β‐diketiminato ligands and one amido group in a distorted trigonal bipyramid. All the complexes were found to be highly active in the ring‐opening polymerization of L‐lactide (L‐LA) and ε‐caprolactone (ε‐CL) to give polymers with relatively narrow molar mass distributions. The activity depends on both the central metal and the ligand (Yb < Y < Sm ≈ Nd and L^2‐Me < L^2,6‐iPr2_Ph). Remarkably, the binary 3/benzyl alcohol (BnOH) system exhibited a striking ‘immortal’ nature and proved able to quantitatively convert 5000 equiv. of L‐LA with up to 100 equiv. of BnOH per metal initiator. All the resulting PLAs showed monomodal, narrow distributions (M_w/M_n = 1.06 ? 1.08), with molar mass (M_n) decreasing proportionally with an increasing amount of BnOH. The binary 4/BnOH system also exhibited an ‘immortal’ nature in the polymerization of ε‐CL in toluene. Copyright © 2014 John Wiley & Sons, Ltd.     

Metallorganische Verbindungen der Lanthanoide. 93 [1]. Tetramethylcyclopentadienyl-Komplexe ausgewählter 4f-Elemente

Organometallic Compounds of the Lanthanides. 93. Tetramethylcyclopentadienyl Complexes of Selected 4f-Elements The trichlorides of lanthanum, neodymium, samarium, and terbium react with Na(C₅Me₄H) in THF to yield the homoleptic complexes Ln(C₅Me₄H)₃ [Ln = La ( 1a ), Nd ( 1b ), Sm ( 1c ), Tb ( 1d )]. On the other hand the reactions of HoCl₃, TmCl₃, and LuCl₃ with Na(C₅Me₄H) result only with formation of the dicyclopentadienyl complexes (C₅Me₄H)₂LnCl(THF) [Ln = Ho ( 2e ), Tm ( 2f ), Lu ( 2h )]. The metallocenes (C₅Me₄H)₂Ln(THF)₂ [Ln = Sm ( 3c ), Yb ( 3g )] are obtained by the reactions of LnI₂ (Ln = Sm, Yb) with Na(C₅Me₄H). The ¹H- and ¹³C-NMR spectra as well as the X-ray crystal structure of the triscyclopentadienyl complexes 1 a and 1 c are discussed.     

PrB7−: A Praseodymium‐Doped Boron Cluster with a PrII Center Coordinated by a Doubly Aromatic Planar η7‐B73− Ligand

The structure and bonding of a Pr‐doped boron cluster (PrB₇⁻) are investigated using photoelectron spectroscopy and quantum chemistry. The adiabatic electron detachment energy of PrB₇⁻ is found to be low [1.47(8) eV]. A large energy gap is observed between the first and second detachment features, indicating a highly stable neutral PrB₇. Global minimum searches and comparison between experiment and theory show that PrB₇⁻ has a half‐sandwich structure with C_6v symmetry. Chemical bonding analyses show that PrB₇⁻ can be viewed as a Pr^II[η⁷‐B₇³⁻] complex with three unpaired electrons, corresponding to a Pr (4f²6s¹) open‐shell configuration. Upon detachment of the 6s electron, the neutral PrB₇ cluster is a highly stable Pr^III[η⁷‐B₇³⁻] complex with Pr in its favorite +3 oxidation state. The B₇³⁻ ligand is found to be highly stable and doubly aromatic with six delocalized π and six delocalized σ electrons and should exist for a series of lanthanide M^III[η⁷‐B₇³⁻] complexes.     

A Nickel Complex Containing a Pyramidalized,Ambiphilic Pincer Germylene Ligand

Reaction of N-heterocyclic carbene (NHC)-stabilized PGeP-type germylene Ge{o-(PiPr₂)C₆H₄}₂⋅^MeIiPr ( 1 ) (^MeIiPr=1,3-diisopropyl-4,5-dimethylimidazol-2-ylidene) with Ni(cod)₂ gave pincer germylene complex Ni[Ge{o-(PiPr₂)C₆H₄}₂](^MeIiPr) ( 2 ), in which the Ge center of 2 is significantly pyramidalized. Theoretical calculation on 2 predicted the ambiphilicity of the germanium center, which was confirmed by reactivity studies. Thus, complex 2 reacted with both Lewis base ^MeIMe (^MeIMe=1,3,4,5-tetramethylimidazol-2-ylidene) and Lewis acid BH₃⋅SMe₂ at the germanium center to afford the adducts Ni[Ge{o-(PiPr₂)C₆H₄}₂⋅^MeIMe](^MeIiPr) ( 3 ) and Ni[Ge{o-(PiPr₂)C₆H₄}₂⋅BH₃](^MeIiPr) ( 4 ), respectively. Furthermore, the former was slowly converted to dinuclear complex Ni₂[Ge{o-(PiPr₂)C₆H₄}₂]₂(^MeIMe)₂ ( 5 ) at room temperature. Complex 5 can be regarded as a dimer of the ^MeIMe analog of 2 with a Ni-Ge-Ge-Ni linkage.     

Synthesis and Structure of a 2, 8, 9‐Trioxa‐3, 5, 7‐trisila‐1‐titanaadamantane

The title compound has been prepared from [Ti(η⁵‐C₅Me₅)Cl₃] and cis‐cis‐(t‐BuSi(OH)—CH₂)₃ in hexane solution in the presence of Et₃N. The pale yellow complex was characterized by NMR and MS spectra, as well as by a crystal structure determination. The two crystallographic independent molecules in the triclinic unit cell (space group P1¯, No. 2, Z = 4) both have a nearly identical adamantane‐like TiO₃Si₃C₃ cage of approximate C_3v symmetry. The exocyclic C—C—C bond angles in the Cp‐ligand range from 123° to 129°. A quantum chemical calculation of the free molecule predicts this range to be 124° to 127°. The arrangement of the molecules in the crystal is characteristic for an offset face‐to‐face ππ stacking of the aromatic η⁵‐C₅Me₅ rings.     

Lanthanide versus Actinide Reactivity in the Formation of Sterically Crowded [(C5Me5)3MLn] Nitrile and Isocyanide Complexes

The limits of steric crowding in organometallic metallocene complexes have been examined by studying the synthesis of [(C₅Me₅)₃ML_n] complexes as a function of metal in which L=Me₃CCN, Me₃CNC, and Me₃SiCN. The bis(tert‐butyl nitrile) complexes [(C₅Me₅)₃Ln(NCCMe₃)₂] (Ln=La, 1 ; Ce, 2 ; Pr, 3 ) can be isolated with the largest lanthanide metal ions, La³⁺, Ce³⁺, and Pr³⁺. The Pr³⁺ ion also forms an isolable mono‐nitrile complex, [(C₅Me₅)₃Pr(NCCMe₃)] ( 4 ), whereas for Nd³⁺ only the mono‐adduct [(C₅Me₅)₃Nd(NCCMe₃)] ( 5 ) was observed. With smaller metal ions, Sm³⁺ and Y³⁺, insertion of Me₃CCN into the M? C(C₅Me₅) bond was observed to form the cyclopentadiene‐substituted ketimide complexes [(C₅Me₅)₂Ln{NC(C₅Me₅)(CMe₃)}(NCCMe₃)] (Ln=Sm, 6 ; Y, 7 ). With tert‐butyl isocyanide ligands, a bis‐isocyanide product can be isolated with lanthanum, [(C₅Me₅)₃La(CNCMe₃)₂] ( 8 ), and a mono‐isocyanide product with neodymium, [(C₅Me₅)₃Nd(CNCMe₃)] ( 9 ). Silicon–carbon bond cleavage was observed in reactions between [(C₅Me₅)₃Ln] complexes and trimethylsilyl cyanide, Me₃SiCN, to produce the trimeric cyanide complexes [{(C₅Me₅)₂Ln(μ‐CN)(NCSiMe₃)}₃] (Ln=La, 10 ; Pr, 11 ). With uranium, a mono‐nitrile reaction product, [(C₅Me₅)₃U(NCCMe₃)] ( 12 ), which is analogous to 5 , was obtained from the reaction between [(C₅Me₅)₃U] and Me₃CCN, but [(C₅Me₅)₃U] reacts with Me₃CNC through C? N bond cleavage to form a trimeric cyanide complex, [{(C₅Me₅)₂U(μ‐CN)(CNCMe₃)}₃] ( 13 ).     

Bis[μ3‐1,8‐bis(triisopropylsilylamido)naphthalene]bis(tetrahydrofuran)di‐μ3‐oxido‐dimanganese(III)disodium

The solid‐state structure of the title compound, [Na₂Mn₂(C₃₂H₅₆N₂OSi₂)₂O₂] or [1,8‐C₁₀H₆(NSiⁱPr₃)₂Mn(μ₃‐O)Na(THF)]₂, which lies across a crystallographic twofold axis, exhibits a central [Mn₂O₂Na₂]⁴⁺ core, with two oxide groups, each triply bridging between the two Mn^III ions and an Na⁺ ion. Additional coordination is provided to each Mn^III centre by a 1,8‐C₁₀H₆(NSiⁱPr₃)₂ [1,8‐bis(triisopropylsilylamido)naphthalene] ligand and to the Na⁺ centres by a tetrahydrofuran molecule. The presence of an additional Na...H—C agostic interaction potentially contributes to the distortion around the bridging oxide group.     

A Mixed‐Valence {Fe13} Cluster Exhibiting Metal‐to‐Metal Charge‐Transfer‐Switched Spin Crossover

It is promising and challenging to manipulate the electronic structures and functions of materials utilizing both metal‐to‐metal charge transfer (MMCT) and spin‐crossover (SCO) to tune the valence and spin states of metal ions. Herein, a metallocyanate building block is used to link with a Fe^II‐triazole moiety and generates a mixed‐valence complex {[(Tp^4‐Me)Fe^III(CN)₃]₉[Fe^II₄(trz‐ph)₆]}?[Ph₃PMe]₂?[(Tp^4‐Me)Fe^III(CN)₃] ( 1 ; trz‐ph=4‐phenyl‐4H‐1,2,4‐triazole). Moreover, MMCT occurs between Fe^III and one of the Fe^II sites after heat treatment, resulting in the generation of a new phase, {[(Tp^4‐Me)Fe^II(CN)₃][(Tp^4‐Me)Fe^III(CN)₃]₈ [Fe^IIIFe^II₃(trz‐ph)₆]}? [Ph₃PMe]₂?[(Tp^4‐Me)Fe^III(CN)₃] ( 1 a ). Structural and magnetic studies reveal that MMCT can tune the two‐step SCO behavior of 1 into one‐step SCO behavior of 1 a . Our work demonstrates that the integration of MMCT and SCO can provide a new alternative for manipulating functional spin‐transition materials with accessible multi‐electronic states.