Bis(di-tert-butylindenyl)tetrelocenes.

The synthesis and characterization of bis(di-tert-butylindenyl) germanium(II), tin(II) and lead(II) complexes are reported, which includes the first structurally authenticated example of a bis(indenyl)germanocene. The species were studied in detail in solution and in the solid, which includes single crystal X-ray diffraction and NMR spectroscopy, as well as Mössbauer spectroscopy of the tin compound.

Non-innocent cyanido ligands: tetracyanidoferrate(-II) as carbonyl copycat.

While a negative oxidation state occurs rarely for metals in general, this is commonly known for metal carbonyl anions, i.e. carbonyl metalates. Although CO and CN- are isoelectronic, cyanidometalates usually do not exhibit metal centers with negative oxidation states. However, we report on the electron-rich tetrahedral tetracyanidoferrate(-II) anion [Fe(CN)4]6-, which was stabilized in (Sr3N)2[Fe(CN)4] (space group R3c, a = 702.12(2) pm, c = 4155.5(2) pm). Microcrystalline powders were synthesized by a solid-state route, single crystals were obtained from Na metal flux. In comparison to classical cyanidometalates, C-N distances are longer and stretching frequencies are lower as indicated by X-ray diffraction, IR and Raman spectroscopy. Weak C-N, strong Fe-C bonds as well as the anion geometry resemble the isoelectronic tetrahedral carbonyl ferrate [Fe(CO)4]2-. 57Fe Mössbauer spectroscopic measurements reveal a negative isomer shift in agreement with substantially delocalized d electrons due to strong π back-bonding. These results point to a very similar bonding situation of both 18e tetracyanido and tetracarbonyl ferrates including non-innocent redox-active ligands and a d10 closed shell configuration on iron. Hereby, new tetracyanidoferrate(-II) provides a missing link for a more in-depth understanding of the chemical bonding trends of highly-reduced cyanidometalates in the quest for even higher reduced transition metals in this exceptional class of compounds.

Trivalent Antimony as L-, X-, and Z-Type Ligand: The Full Set of Possible Coordination Modes in Pt-Sb Bonds.

In the course of our investigations of the coordination chemistry of trivalent antimony (Sb) compounds, we studied heteronuclear complexes formed in reactions of the compounds RSb(pyS)2 (R = pyS, Ph; pyS- = pyridine-2-thiolate) with [Pt(PPh3)4], i.e., complexes [(R)Sb(µ-pyS)2Pt(PPh3)] (R = pyS, 1; R = Ph, 2). The reaction of 1 with o-chloranil proceeds cleanly with elimination of 2,2'-dipyridyl disulfide and formation of the salt [(PPh3)Pt(µ-pyS)2Sb(µ-pyS)2Pt(PPh3)]+[Sb(C6Cl4O2)2]- (3III), which features the cation 3+. The charge-neutral, unsymmetrically substituted compound [(PPh3)Pt(µ-pyS)2Sb(µ-pyS)2Pt(κS-pyS)] (4) can be accessed by the reaction of 3+ with LipyS. The oxidation of 2 with o-chloranil furnishes the complex [(κ-O,O-C6Cl4O2)PhSb(µ-pyS)2Pt(PPh3)] (5). The oxidation of 1 with PhICl2 afforded the paddlewheel-shaped complex [Sb(µ-pyS)4PtCl] (6). Moreover, compound 6 was obtained by the reaction of Sb(pyS)3 with [PtCl(pyS)(PPh3)]. The polarization of Pt-Sb bonds of compounds 1-6 was investigated by natural localized molecular orbital (NLMO) calculations, which suggest X-type ligand character (covalent Pt-Sb bonds) for 1 and 2, whereas the Sb ligand of 6 reflects Z-type character (dative Pt→Sb bonds). In 3+, 4, and 5, high contributions of the reverse, i.e., L-type (dative Pt←Sb bonds), were observed. In conjunction with the results of NLMO analyses, 121Sb Mössbauer spectroscopy proves that complexes 1-6 represent essentially trivalent Sb complexes with either a free lone pair (LP) at the Sb atom (1, 2, and 6) or LP character involved in L-type Pt←Sb coordination (3+, 4, and 5).

The Earlier the Better: Structural Analysis and Separation of Lanthanides with Pyrroloquinoline Quinone.

Lanthanides (Ln) are critical raw materials, however, their mining and purification have a considerable negative environmental impact and sustainable recycling and separation strategies for these elements are needed. In this study, the precipitation and solubility behavior of Ln complexes with pyrroloquinoline quinone (PQQ), the cofactor of recently discovered lanthanide (Ln) dependent methanol dehydrogenase (MDH) enzymes, is presented. In this context, the molecular structure of a biorelevant europium PQQ complex was for the first time elucidated outside a protein environment. The complex crystallizes as an inversion symmetric dimer, Eu2 PQQ2 , with binding of Eu in the biologically relevant pocket of PQQ. LnPQQ and Ln1Ln2PQQ complexes were characterized by using inductively coupled plasma mass spectrometry (ICP-MS), infrared (IR) spectroscopy, 151 Eu-Mössbauer spectroscopy, X-ray total scattering, and extended X-ray absorption fine structure (EXAFS). It is shown that a natural enzymatic cofactor is capable to achieve separation by precipitation of the notoriously similar, and thus difficult to separate, lanthanides to some extent.

Eu(O2 C-C≡C-CO2 ): An EuII Containing Anhydrous Coordination Polymer with High Stability and Negative Thermal Expansion.

Anhydrous EuII -acetylenedicarboxylate (EuADC; ADC2- = - O2 C-C≡C-CO2 - ) was synthesized by reaction of EuBr2 with K2 ADC or H2 ADC in degassed water under oxygen-free conditions. EuADC crystallizes in the SrADC type structure (I41 /amd, Z=4) forming a 3D coordination polymer with a diamond-like arrangement of Eu2+ nodes (msw topology including the connecting ADC2- linkers). Deep orange coloured EuADC is stable in air and starts decomposing upon heating in an argon atmosphere only at 440 °C. Measurements of the magnetic susceptibilities (µeff =7.76 µB ) and 151 Eu Mössbauer spectra (δ=-13.25 mm s-1 at 78 K) confirm the existence of Eu2+ cations. Diffuse reflectance spectra indicate a direct optical band gap of Eg =2.64 eV (470 nm), which is in accordance with the orange colour of the material. Surprisingly, EuADC does not show any photoluminescence under irradiation with UV light of different wavelengths. Similar to SrADC, EuADC exhibits a negative thermal volume expansion below room temperature with a volume expansion coefficient αV =-9.4(12)×10-6  K-1 .

[SnI8 {Fe(CO)4 }4 ]2+ : Highly Coordinated Sn+II I8 Subunit with Fragile Carbonyl Clips.

[SnI8 {Fe(CO)4 }4 ][Al2 Cl7 ]2 contains the [SnI8 {Fe(CO)4 }4 ]2+ cation with an unprecedented highly coordinated, bicapped SnI8 prism. Given the eightfold coordination with the most voluminous stable halide, it is all the more surprising that this SnI8 arrangement is surrounded only by fragile Fe(CO)4 groups in a clip-like fashion. Inspite of a predominantly ionic bonding situation in [SnI8 {Fe(CO)4 }4 ]2+ , the I- ⋅⋅⋅I- distances are considerably shortened (down to 371 pm) and significantly less than the van der Waals distance (420 pm). The title compound is characterized by single-crystal structure analysis, spectroscopic methods (EDXS, FTIR, Raman, UV/Vis, Mössbauer), thermogravimetry, and density functional theory methods.

Antiferromagnetic Alkali Metal Oxohydroxoferrates(III) with Correlated Hydrogen Bonding Systems.

The oxohydroxoferrates(III) A 2[Fe2O3(OH)2] (A=K, Rb, Cs) were synthesized under hydroflux conditions. Approximately equimolar mixtures of the alkali metal hydroxides and water were reacted with Fe(NO3)3 ⋅ 9H2O at about 200 °C. The product formation depends on the hydroxide concentration, therefore also other reaction products, such as KFeO2, K2-x[Fe4O7-x(OH)x] or α-Fe2O3, are obtained. The crystal structures of the oxohydroxoferrates(III) A 2[Fe2O3(OH)2] follow the same structural principle, yet differ in their layer stacking or/and their hydrogen bonding systems depending on A and temperature. In the resulting four different orthorhombic structure types, [FeO3OH]4- tetrahedra share their oxide corners to create folded ∞ 2 [ Fe2O3(OH)2]2- layers. The terminal hydroxide ligands form hydrogen bonds between and/or within the layers. The positions of the hydrogen atoms in these networks are correlated. The A + cations are located between the folded anionic layers as well as in their trenches. Under reaction conditions, the potassium compound crystallizes in the space group Cmce (Pearson symbol oC88), showing a bimodal disorder of the hydrogen atoms in hydrogen bridges. In a virtually hysteresis-less first-order transition at 340(2) K, the structure slightly distorts into the room-temperature modification with the subgroup Pbca (oP88), and the hydrogen atoms order. The rubidium and caesium compounds are isostructural to each other but not to the potassium compound, and are always obtained as mixtures of two modifications with space groups Cmce (oC88') and Immb (oI88). Upon heating, the oxohydroxoferrates decompose into their anhydrides AFeO2 and water. The type of hydrogen bonding network influences the decomposition temperature, the structure and the morphology of the crystals. Despite the presence of iron(III), which was confirmed by 57Fe-Mössbauer spectroscopy, K2[Fe2O3(OH)2] is diamagnetic in the investigated temperature range between 1.8 and 300 K. Neutron diffraction revealed strong antiferromagnetic coupling of the magnetic moments, which are inverted in neighboring tetrahedra.

Lithiumpyridinyl-Driven Synthesis of High-Purity Zero-Valent Iron Nanoparticles and Their Use in Follow-Up Reactions.

The synthesis of zero-valent iron (Fe(0)) nanoparticles in pyridine using lithium bipyridinyl ([LiBipy]) or lithium pyridinyl ([LiPy]) is presented. FeCl3 is used as the most simple starting material and reduced either in a [LiBipy]-driven two-step approach or in a [LiPy]-driven one-pot synthesis. High-quality nanoparticles are obtained with uniform, spherical shape, and mean diameters of 2.9 ± 0.5 nm ([LiBipy]) or 4.1 ± 0.7 nm ([LiPy]). The as-prepared, high purity Fe(0) nanoparticles are monocrystalline. In addition to particle characterization (high-resolution transmission electron microscopy, scanning transmission electron microscopy, dynamic light scattering), composition and purity are examined in detail based on electron diffraction, X-ray powder diffraction, elemental analysis, infrared spectroscopy, 57 Fe Mössbauer spectroscopy, and magnetic measurements. Due to their small size and high purity, the Fe(0) nanoparticles are highly reactive. They can be used in follow-up reactions to obtain a variety of iron compounds, which is exemplarily shown for the transformation to iron carbide (Fe3 C) nanoparticles, the reaction with sulfur to obtain FeS nanoparticles, or the direct reaction with pentamethylcyclopentadiene to FeCp*2 (Cp*: pentamethylcyclopentadienyl).

Antimony(i) → Pd(ii) complexes with the (µ-Sb)Pd2 coordination framework.

The reaction of the antimony(i) compound ArSb (1) (where Ar = C6H3-2,6-(CH[double bond, length as m-dash]NtBu)2) with various dimeric allyl palladium(ii) complexes [Pd(η3-allyl)(µ-X)]2 (where allyl = C3H5 or C3H4Me; X = Cl or CF3CO2) in a 1 : 1 stoichiometric ratio gave unique complexes with the µ-ArSb moiety bridging two palladium fragments, i.e. [{Pd(η3-C3H5)Cl}2(µ-ArSb)] (2), [{Pd(η3-C3H4Me)Cl}2(µ-ArSb)] (3) and [{Pd(η3-C3H5)(CF3CO2)}2(µ-ArSb)] (4). Compound 1 serves formally as a 4e donor in 2-4. The treatment of 2 with another equivalent of ArSb led to the formation of the [Pd(η3-C3H5)(Cl)(µ-ArSb)] complex (5), proving that 1 is able to function as a 2e donor in target complexes as well. The structures of 2-5 were described in detail both in solution (NMR and mass spectrometry) and in the solid state (single crystal X-ray diffraction analysis). DFT methods were used to compare bonding in the 1 : 1 (5) and 1 : 2 (2) complexes. Furthermore, a comprehensive 121Sb Mössbauer spectroscopic investigation of complexes 2 and 5 along with parent ArSbCl2 (6) and 1 was performed. For comparison, complexes [Fe(CO)4(ArSb)] (7) and [Mo(CO)5(ArSb)] (8) were also included in this study.

From 3D to 2D: Structural, Spectroscopic and Theoretical Investigations of the Dimensionality Reduction in the [PtAl2 ]δ- Polyanions of the Isotypic MPtAl2 Series (M=Ca-Ba, Eu).

Four new MPtAl2 (M=Ca, Sr, Ba, Eu) compounds, adopting the orthorhombic MgCuAl2 -type structure, have been synthesized from the elements using tantalum ampoules. All compounds are obtained as platelet-shaped crystallites and exhibit an increasing moisture sensitivity with increasing size of the formal M cation. Structural investigations indicate a pronounced elongation of the crystallographic b-axis, which results in a significant distortion of the [PtAl2 ]δ- polyanion. Within the polyanion, layer-like arrangements can be found with bonding Pt-Al interactions within the slab; the increase of the b-axis can be attributed to increasing Al-Al distances and therefore decreasing interactions between the slabs, caused by the differently-sized formal M cations. While the alkaline earth (M=Ca, Sr) representatives exhibit Pauli paramagnetism, BaPtAl2 shows diamagnetic behavior, finally EuPtAl2 is ferromagnetic with TC =54.0(5) K. The effective magnetic moment indicates that the Eu atoms are in a divalent oxidation state, which is confirmed by 151 Eu Mössbauer spectroscopic investigations. Measurements below the Curie-temperature show a full magnetic hyperfine field splitting with Bhf =21.7(1) T. 27 Al and 195 Pt magic-angle spinning NMR spectroscopy corroborates the presence of single crystallographic sites for the Pt and Al atoms. The large 27 Al nuclear electric quadrupolar coupling constants confirm unusually strong electric field gradients, in agreement with the structural distortions and the respective theoretical calculations. X-ray photoelectron spectroscopy has been utilized to investigate the charge transfer within the polyanion. The Pt 4f binding energy decreases with decreasing electronegativity / ionization energy of the alkaline earth elements, suggesting an increasing electron density at the Pt atoms. Theoretical investigations underline the platinide character of the investigated compounds by Bader charge calculations. The analysis of the integrated crystal orbital Hamilton population (ICOHP) values, electron localization function (ELF) and isosurface analyses lead to a consistent structural picture, indicating stable layer-like arrangements of the [PtAl2 ]δ- polyanion.

RE2[B2(SO4)6] (RE = Y, La-Nd, Sm, Eu, Tb-Lu): a silicate-analogous host structure with weak coordination behaviour.

The rare earth borosulfates RE2[B2(SO4)6] with RE = Y, La-Nd, Sm, Eu and Tb-Lu were synthesised under solvothermal conditions starting from the metal chlorides (Pr, Nd, Eu), the metal oxides (Y, La, Ce, Sm, Tb, Dy, Er, Tm, Lu), or the metal powders (Ho, Yb). They crystallize isotypically with Gd2[B2(SO4)6] in space group C2/c (Z = 4, a = 1346.9(3)-1379.24(17) pm, b = 1136.4(3)-1158.87(14) pm, c = 1079.9(3)-1139.54(14) pm, ß = 93.369(8)-93.611(4)°). The anionic structure consists of an open-branched vierer single ring {oB, 1r}[B2S2O12(SO3)4]6-, similar to the mineral eakerite (Ca2Al2Sn[Si6O18](OH)2·2H2O) which contains {oB, 1r}[Si4O12(SiO3)2]12- moieties. The fluorescence spectroscopy of the samples with RE = Ce, Eu and Tb features emissions in the deep UV, the red, and the green part of the spectrum and furthermore revealed a weak coordination behaviour of the borosulfate anion. Thermal analysis of Eu2[B2(SO4)6] showed the highest thermal stability observed for borosulfates so far; respective trends within the borosulfate family are discussed. Additionally, the compounds were characterised by magnetic measurements, vibrational and 151Eu Mößbauer spectroscopy.

Oxo-Hydroxoferrate K2-x Fe4O7-x (OH) x : Hydroflux Synthesis, Chemical and Thermal Instability, Crystal and Magnetic Structures.

The reaction of Fe(NO3)3⋅9 H2O with KOH under hydroflux conditions at about 200 °C produces red crystals of K2-x Fe4O7-x (OH) x in a quantitative yield. In the crystal structure, edge-sharing [FeO6] octahedra form ∞ 2 [ Fe2O6] honeycomb nets. Pillars consisting of pairs of vertex-sharing [FeO4] tetrahedra link the honeycomb layers and form columnar halls in which the potassium ions are located. The trigonal (P 3 ‾ 1m) and the hexagonal (P63/mcm) polytypes of K2-x Fe4O7-x (OH) x show oriented intergrowth. The sub-stoichiometric potassium content (x≈0.3) is compensated by hydroxide ions. K2-x Fe4O7-x (OH) x is an antiferromagnet above 2 K and its magnetic structure was determined by neutron powder diffraction. Under ambient conditions, K2-x Fe4O7-x (OH) x hydrolyzes and K2CO3 ⋅ H2O forms gradually on the surface of the K2-x Fe4O7-x (OH) x crystals. Upon annealing at air at about 500 °C, the potassium atoms in the columnar halls start to order into a superstructure. The thermal decomposition of K2-x Fe4O7-x (OH) x proceeds via a topotactic transformation into K1+x' Fe11O17, adopting the rhombohedral ß'' or the hexagonal ß-aluminate-type structure, before γ-Fe2O3 is formed above 950 °C, which then converts into thermodynamically stable α-Fe2O3.

An Unusual Valence State: Trivalent Europium in Intermetallic Eu2 Ir3 Al9.

Eu2 Ir3 Al9 , synthesized from the elements in tantalum tubes, is one of the rare examples for trivalent europium in the field of intermetallic compounds. The compound crystallizes in the Y2 Co3 Ga9 -type structure (space group Cmcm), with lattice parameters fitting in between the isostructural samarium and gadolinium compounds. In the crystal structure, the Eu atoms form Al3 -triangle-centered honeycomb layers and exhibit a coordination number of 17 in the shape of a fivefold-capped hexagonal prism (Eu@Ir6 Al6 +Al5 ). Magnetic measurements indicate an overall low susceptibility, in line with van Vleck paramagnetism caused by the Eu3+ cations. Fits of the susceptibility yield a coupling constant of λ=290(10) K and an effective magnetic moment of µeff =4.56(1) µB , in line with a slight hybridization of the 7 F0 and 7 F1 state. 151 Eu Mössbauer spectroscopic investigations unambiguously prove the presence of solely Eu3+ in the bulk material.

Open-Shell 3d Transition Metal Nitridophosphates MII P8 N14 (MII =Fe, Co, Ni) by High-Pressure Metathesis.

3d transition metal nitridophosphates MII P8 N14 (MII =Fe, Co, Ni) were prepared by high-pressure metathesis indicating that this route might give a systematic access to a structurally rich family of M-P-N compounds. Their structures, which are stable in air up to at least 1273 K, were determined through powder X-ray diffraction and consist of highly condensed tetra-layers of PN4 tetrahedra and MN6 octahedra. Magnetic measurements revealed paramagnetic behavior of CoP8 N14 and NiP8 N14 down to low temperatures while, FeP8 N14 exhibits an antiferromagnetic transition at TN =3.5(1) K. Curie-Weiss fits of the paramagnetic regime indicate that the transition metal cations are in a oxidation state +II, which was corroborated by Mössbauer spectroscopy for FeP8 N14 . The ligand field exerted by the nitride ions in CoP8 N14 and NiP8 N14 was determined from UV/Vis/NIR data and is comparable to that of aqua-ligands and oxophosphates.

Synthesis of a Cyclic Co2Sn2 Cluster Using a Co- Synthon.

[Ar'SnCo]2 (1, Ar' = C6H3-2,6{C6H3-2,6- iPr2}2), a rare metal-metal bonded cobalt-tin cluster with low-coordinate tin atoms, was prepared by the reaction of [K(thf)0.2][Co(1,5-cod)2] (cod = 1,5-cyclooctadiene) with [Ar'Sn(µ-Cl)]2. This reaction illustrates a promising synthetic strategy to access uncommon metal clusters. The structure of 1 features a rhomboidal Co2Sn2 core with strong metal-metal bonds between tin and cobalt and a weaker tin-tin interaction. Reaction of 1 with white phosphorus afforded [Ar'2Sn2Co2P4] (2), the first molecular cluster compound containing phosphorus, cobalt and tin.

Abrupt Europium Valence Change in Eu2Pt6Al15 around 45 K.

Eu2Pt6Al15 has been prepared from the elements via arc-melting and subsequent temperature treatment; the structure was refined from single crystal X-ray diffraction data. The compound crystallizes in an orthorhombic (3 + 1)D commensurately modulated structure (Sc2Pt6Al15 type) with space group Cmcm(α,0,0)0 s0 (α = 2/3). Full ordering of the Pt and Al atoms within the [Pt6Al15]δ- polyanion was observed. Magnetic measurements revealed an anomaly in the susceptibility data at T = 41.6(1) K, which was also observed as λ-type anomaly in heat capacity measurements ( T = 40.7(1) K). Temperature dependent powder X-ray diffraction experiments indicated a drastic shortening of the c axis (-18 pm, -1.1%) around 45 K, while the a axis nearly remains the same (-1 pm, -0.2%). Measurements of the electrical resistivity verified the anomaly, indicating a clear change in the electronic structure of the material. The observed anomalies in the physical measurements can be explained by a temperature driven first order valence change from Eu2+ at higher temperatures (>55 K) to Eu3+ at low temperatures. This valence change was proven by temperature dependent 151Eu Mössbauer spectroscopic investigations. Isostructural Eu2Pt6Ga15 was prepared in comparison, and it shows divalent Eu atoms down to 2.5 K along with antiferromagnetic ordering at TN = 13.1(1) K.

LiGe(SiMe3)3: A New Substituent for the Synthesis of Metalloid Tin Clusters from Metastable Sn(I) Halide Solutions.

The most fruitful synthetic route to metalloid tin clusters applies the disproportionation reaction of metastable Sn(I) halide solutions, whereby Si(SiMe3)3 is mostly used as the stabilizing substituent. Here, we describe the synthesis and application of the slightly modified substituent Ge(SiMe3)3, which can be used for the synthesis of metalloid tin clusters to give the neutral cluster Sn10[Ge(SiMe3)3]6 as well as the charged clusters {Sn10[Ge(SiMe3)3]5}− and {Sn10[Ge(SiMe3)3]4}2−. The obtained metalloid clusters are structurally similar to their Si(SiMe3)3 derivatives. However, differences with respect to the stability in solution are observed. Additionally, a different electronic situation for the tin atoms is realized as shown by 119mSn Mössbauer spectroscopy, giving further insight into the different kinds of tin atoms within the metalloid cluster {Sn10[Ge(SiMe3)3]4}2−. The synthesis of diverse derivatives gives the opportunity to check the influence of the substituent for further investigations of metalloid tin cluster compounds.

Cyclic Distannene or Bis(stannylene) with a Ferrocenyl Backbone: Synthesis, Structure, and Coordination Chemistry.

1,1'-Dilithioferrocene was reacted with 2 equiv of isopropyl (Ar*) or methyl (Ar') substituted terphenyl tin(II) chloride. Reaction product 1, carrying the bulkier terphenyl substituent Ar*, displays a bis(stannylene) structure in the solid state without formation of a tin-tin bond. Temperature-dependent solution 119Sn NMR spectroscopy, however, revealed a dynamic interplay between bis(stannylene) (100 °C) and cyclic distannene (-80 °C). In contrast to 1, the less bulky Ar' substituent results in a cyclic distannene 2. On the basis of temperature-dependent 119Sn NMR spectroscopy the Sn-Sn bond of compound 2 was preserved up to 100 °C. Both compounds were further characterized by solid-state 119Sn NMR spectroscopy as well as 119Sn and 57Fe Mössbauer spectroscopy. 1 reacted as a chelating ligand with nickel and palladium complexes [Ni(cod)2] and [Pd(nbe)3] (nbe = norbornene). In the resulting coordination compounds the nonstabilized stannylene acts as a donor as well as an acceptor ligand and shows a dynamic switch from donor to acceptor behavior in the monopalladium complex.

Ternary Mixed-Valence Organotin Copper Selenide Clusters.

Reactions of the organotin selenide chloride clusters [(R1 SnIV )3 Se4 Cl] (A, R1 =CMe2 CH2 C(O)Me) or [(R1 SnIV )4 Se6 ] (B) with [Cu(PPh3 )3-x Clx ] yield cluster compounds with different inorganic, mixed-valence core structures: [Cu4 SnII SnIV6 Se12 ], [Cu2 SnII2 SnIV4 Se8 Cl2 ], [Cu2 SnII SnIV4 Se8 ], [Cu2 SnII2 SnIV2 Se4 Cl4 ], and [Cu2 SnIV2 Se4 ]. Five of the compounds, namely [(CuPPh3 )2 {(R1 SnIV )2 Se4 }] (1), [(CuPPh3 )2 SnII {(R2 SnIV )2 Se4 }2 ] (2), [(CuPPh3 )2 (SnII Cl)2 {(RSnIV )2 Se4 }2 ] (3) [(CuPPh3 )2 (SnII Cu2 ){(R1 SnIV )2 Se4 }3 ] (4), and [Cu(CuPPh3 )(SnII Cu2 ){(R1 SnIV )2 Se4 }3 ] (5) are structurally closely related. They are based on [(CuPPh3 )2 {(RSnIV )2 Se4 }n ] aggregates comprising [(RSnIV )2 Se4 ] and [CuPPh3 ] building units, which are linked by further metal atoms. A sixth compound, [(CuPPh3 )2 (SnII Cl)2 {(R1 SnIV Cl)Se2 }2 ] (6), differs from the others by containing [(RSnIV Cl)Se2 ] units instead, which affects the absorption properties. The compounds were analyzed by single-crystal X-ray diffraction, NMR and 119 Sn Mössbauer spectroscopy, DFT calculations as well as optical absorption experiments.