Ein „Lithosilicat”︁ mit Kolumnareinheiten: RbLi5{Li[SiO4]}2

A “Lithosilicate” with Columnar Units: RbLi₅{Li[SiO₄]}₂ In order to prepare RbLi₃[SiO₄] single crystals of RbLi₅{Li[SiO₄]}₂ have been obtained for the first time by heating of a well ground mixture of the binary oxides RbO_0.68, LiO_0.5 and SiO₂ [Rb:Li:Si = 1.1:3.0:1.0; 600°C; 21 d] in tightly closed Ni tubes. The new “lithosilicate” crystallizes monoclinic (space group C2/m with a = 1563.1(2) pm, b = 635.4(1) pm, c = 776.3(1) pm, β = 90.53(1)°, Guinier-Simon powder data). The crystal structure was determined by four-cycle diffractometer data [Philips PW 1100, 1237 from 1609 I_o(hkl), Z = 4, R = 9.2%, R_w = 8.3%], parameters see text. The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, have been calculated.     

Das erste Oxogermanat mit „Stuffed Pyrgoms”︁: CsNa3Li8{Li[GeO4]}4

The First Oxogermanate with “Stuffed Pyrgoms”: CsNa₃Li₈{Li[GeO₄]}₄ By heating the binary oxides CsO_0.52, NaO_0.45, LiO_0.5 and GeO₂ in the mol. ratio 1.24:1.4:6.7:3.9 (Ni tubes; 600°C/89 resp. 65 d) we obtained for the first time CsNa₃Li₈{Li[GeO₄]}₄ in form of pale yellow prisms as well as powder: space group I4/m (I. T. No. 87) with a = 1 120.73(5); c = 651.64(5) pm; Z = 2; (four circle diffractometer data; MoKα; 5 152 I_o(hkl); R = 1.7%; R_w = 1.6%), parameters see text. The structure determination confirmes its being isotypic with CsKNaLi₉{Li[SiO₄]}₄, CsKNa₂Li₈{Li[SiO₄]}₄ and RbNa₃Li₈{Li[SiO₄]}₄. The Madelung part of lattice energy (MAPLE), effective coordination numbers (ECoN), mean fictive ionic radii (MEFIR) and the charge distribution (CHARDI) are calculated.     

Das erste Titanat mit „Stuffed Pyrgoms”︁: RbNa3Li12[TiO4]4 = RbNa3Li8{Li[TiO4]}4

The First Titanate with ?Stuffed Pyrgoms”?: RbNa₃Li₁₂[TiO₄]₄ = RbNa₃Li₈{Li[TiO₄]}₄ By heating a well grounded mixture of the binary oxides Rb₂O, Na₂O, Li₂O, and TiO₂ [Rb:Na:Li:Ti = 1.1:3.1:12.5:4.0; 780°C, 41 d] we obtained RbNa₃Li₈{Li[TiO₄]}₄ as colourless platelike crystals. This first titanate with ?stuffed pyrgoms”? is isostructural with RbNa₃Li₈{Li[SiO₄]}₄, CsKNa₂Li₈{Li[SiO₄]}₄ and CsKNaLi₉{Li[SiO₄]}₄ [2]. The compound crystallizes tetragonal I4/m with a = 1 125.8(1) pm and c = 652.4(1) pm (Guinier-Simon-Data, Z = 2). The structure was determined by four-cyrcle-data (Siemens AED2, MoK) and leds to the residual values R = 3.7% and R_w = 3.1% (additional data see text). The Madelung Part of Lattice Energy (MAPLE), Effective Coordination Numbers (ECoN), Mean Fictive Ionic Raddii (MEFIR) and the Charge Distribution in Solids (CHARDI) are calculated and discussed.     

Neue Silicate mit „Stuffed Pyrgoms”︁: CsKNaLi9{Li[SiO4]}4, CsKNa2Li8{Li[SiO4]}4, RbNa3Li8{Li[SiO4]}4 [1] und RbNaLi4{Li[SiO4]}2 [2]

More Silicates with ?Stuffed Pyrgoms”?: CsKNaLi₉{Li[SiO₄]}₄, CsKNa₂Li₈{Li[SiO₄]}₄, RbNa₃Li₈{Li[SiO₄]}₄ [1] and RbNaLi₄{Li[SiO₄]}₂ [2] Single crystals of the new silicates CsKNaLi₉{Li[SiO₄]}₄, CsKNa₂Li₈{Li[SiO₄]}₄, RbNa₃Li₈{Li[SiO₄]}₄ and RbNaLi₄{Li[SiO₄]}₂ as well as powder (Rb-containing compounds only) were obtained for the first time. The samples were prepared by heating well ground mixtures of the binary oxides in Ni and Ag tubes, respectively. The structure determination was carried out by four-circle diffractometer data (MoKα radiation; Siemens AED 2): CsKNaLi₉{Li[SiO₄]}₄: tetragonally prismatic crystals, light yellow; 726 I₀(hkl), R = 4.4%, R_w = 2.8%; a = 1 102.0(6), c = 637.9(5) pm; Z = 2; space group I4/m; 2 CsO_0.55 + Li₄TlO₄ + glas (560°C, 15 d). CsKNa₂Li₈{Li[SiO₄]}₄: tetragonally prismatic crystals, light yellow; 727 I₀(hkl), R = 4.4%, R_w = 2.6%; a = 1 103.5(7), c = 637.7(4) pm; Z = 2; space group I4/m; 1.1 CsO_0.61 + 1.1 KO_0.55 + 1.4 NaO_0.52 + 6.5 Li₂O + 4 SiO₂ (600°C, 60 d). RbNa₃Li₈{Li[SiO₄]}₄: tetragonally prismatic crystals, colourless; 600 I₀(hkl), R = 2.3%, R_w = 2.0%; a = 1 092.08(6), c = 632.76(4) pm; Z = 2; space group I4/m; 4 RbO_0.57 + 3 NaO_0.52 + 6.5 Li₂O + 4 SiO₂ (650°C, 63 d). RbNaLi₄{Li[SiO₄]}₂: monoclinic, ball-shaped, colourless; 1 224 I₀(hkl), R = 3.1%, R_w = 3.1%; a = 1 573.10(13), b = 630.48(5), c = 781.25(8) pm, b = 90.566(8)°; Z = 4; space group C2/m; 1.1 RbO_0.52 + 1.2 NaO_0.45 + 5 Li₂O + 4 SiO₂ (700°C, 40 d).     

Ketten aus Ringen: K5{Li[Ge2O7]} — das erste „Litho-Digermanat”︁

Chains consisting of Rings: K₅{Li[Ge₂O₇]} — the First ‘Litho-Digermanate’ By heating of a well-ground mixture of the binary oxides KO_0.55, Li₂O and GeO₂ (K: Li: Ge = 6.1 : 2.2 : 2; Ni-tube; 600°C; 49 d) we obtained for the first time single crystals of K₅{Li[Ge₂O₇]}. This ‘lithodigermanate’ represents a completely new type of structure: monoclinic, space group P2₁/c, a = 624.9(2) pm, b = 1586.6(8) pm; c = 1058.3(6) pm and β = 109.38(4)°; Guinier-Simon data, Z = 4. The structure was solved by four-circle diffractometer data [Siemens AED II, Mo? Kα ; 2872 I_o(hkl); R = 4.5%, R_w = 3.3%], parameters see text. The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, these calculated via Mean Fictive Ionic Radii, MEFIR, as well as charge distribution CHARDI, are calculated and discussed.     

Über „Lithovanadate”︁: Zur Kenntnis von Rb2[LiVO4] und Cs2[LiVO4]

On ?Lithovanadates”?: Rb₂[LiVO₄] and Cs₂[LiVO₄] By heating of well ground mixtures of the binary oxides [A₂O, Li₂O, V₂O₅, A : Li: V = 2.2 : 1.1 : 1.0 (A = Rb, Cs); Ni-tube, 750° 25 d] we obtained Rb₂[LiVO₄] and Cs₂[LiVO₄] colourless, orthorhombic single crystals. We found a new type of ?Lithovanadate”?-structure: space group Cmc2₁; a = 587.9(1), b = 1170.1(1), c = 793.3(1) pm, Z = 4 (A = Rb) bzw. a = 610.5(1), b = 1222.6(3), c = 815.5(2) pm, Z = 4 (A = Cs). The structure was determined by four-circle diffractometer data [MoKα -radiation; 997 from 1157 I₀(hkl), R = 7.75%, R_w = 5.54% (A = Rb); 686 from 686 I₀(hkl), R = 6.97%, R_w = 4.20% (A = Cs)] parameters see text. The Madelung part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, have been calculated.     

Das erste „Lithovanadat”︁: K2{LiVO4}.

The First ?Lithovanadate”?: K₂{LiVO₄} By heating of well ground mixtures of the binary oxides [K₂O, Li₂O, V₂O₅, K:Li: V = 2.2:1.1:1.0; Ni-tube, 900°C, 46 d] colourless monoclinic single crystals of K₂[LiVO₄] have been prepared for the first time: space group C2/m; a = 835.7(1) pm, b = 774.5(1) pm, c = 753,3(1) pm, β = 90.23(1)°. The structure was determined by four-circle diffractometer data [MoKα, 1018 form 1262 I₀ (hkl), R = 8.65%, R_w = 5.67%], parameters see text. The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, have been calculated.     

Neue Alkalioxoarsenate (V) Zur Kenntnis von Rb2Li[AsO4] und Cs2Li[AsO4]

New Alkalioxoarsenates (V). On Rb₂Li[AsO₄] and Cs₂Li[AsO₄] By heating of well-grounded mixtures of the binary oxides (A₂O, Li₂O₂, and As₂O₃; A : Li : As = 2 : 1 : 1; Ni-tube, 550°C, 21 d; A = Rb, Cs) colourless single crystals of Rb₂Li[AsO₄] and Cs₂Li[AsO₄] were obtained for the first time. These new orthoarsenates(V) crystalize orthorhombic (space group C mc2₁? C, No. 36) with Z = 4. As expected they are isotypic with the according orthovanadates(V) [2] A₂Li[VO₄], A = Rb, Cs. The lattice constants of Rb₂Li[AsO₄]: a = 582.1(4) pm, b = 1171.1(7) pm, c = 792.4(5) pm and Cs₂Li[AsO₄]: a = 596.4(2) pm, b = 1223.4(2) pm, c = 819.7(3) pm were taken from Guinier-Simon powder data. The structure was determined by four-circle-diffractometer data [Siemens AED II, MoKα , 6290 I₀ (hkl), R = 3.5%, R_w = 3.2% to Rb₂Li[AsO₄]; 3518 I₀ (hkl), R = 2.8%, R_w = 2.6% to Cs₂Li[AsO₄]; parameters see text]. The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, these calculated via Mean Fictive Ionic Radii, MEFIR, as well as charge distribution CHARDI are calculated and discussed.     

Ein Oxomanganat(V) neuen Typs: K11{Li[OMnO3]4}

An Oxomanganate(V) of New Type: K₁₁{Li[OMnO₃]}₄ By heating of well ground mixtures of the oxides [K₂O₂, LiMnO₄, K:Mn = 2.2:1, Ag-tube, 580°C, 30 d] blue-green tetragonal single crystals of K₁₁{Li[OMnO₃]₄} have been prepared for the first time: space group I4 2m; a = 787,18(7) pm, c = 1750.9(3) pm. The structure was determined by four-circle-diffractometer data [MoKα , 1236 from 1303 I_o(h kl), R = 3.9%, R_w = 3.1%], parameters see text. The Madelung Part of Lattice Energy, MAPLE, and the Effective Coordination Numbers, ECoN, these via Mean Fictive Ionic Radii, MEFIR, have been calculated.     

“Fragmentierung” und “Aggregation” bei Bleioxiden Über das Oligooxoplumbat(IV) K2Li6[Pb2O8]

“Fragmentation” and “Aggregation” on Lead Oxides. On the Oligooxoplumbate(IV) K₂Li₆[Pb₂O₈] For the first time, the dinuclear Oxoplumbate(IV) K₂Li₆[Pb₂O₈] has been prepared as transparent colourless single crystals by heating mixtures of K₂PbO₃, Li₂O, and “PbO₂” with K:Li:Pb = 1:3:1 e. g. [Ag-cylinders, sealed under vacuum in Supremax-glass ampoule, 660°C, 120 d]. The structure determination verifies the space group P1 with a = 6.9720(9), b = 5.9252(6), c = 5.9312(7) Å, α = 88.05(1)°, β = 107.94(1)°, γ = 107.30(1)°; d_x = 4.95 g · cm^?3, d_pyk = 4.91 g · cm^?3; Z = 1, [2107 symmetry independent hkl, fourcircle-diffractometer Philips PW 1100, ω—2Θ—scan, MoKα, R = 5.07%, R_w = 4.59%, absorption not considered]. The structure is characterized by the group [Pb₂O₈] — two edge connected (equatorial/apical) trigonal bipyramids — that is observed for the first time. Several ways of synthesis are given. The Madelung Part of Lattice Energy, MAPLE, Effective Coordination Numbers, ECoN, these via Mean Effective Ionic Radii, MEFIR, are calculated.     

Kristallstruktur des „supramolekularen”︁ Komplexes [Cs2(18-Krone-6)][HgI4] mit ungewöhnlich koordinierten Cs-Ionen

Crystal Structure of the “Supramolecular” Complex [Cs₂(18-crown-6)][HgI₄] with Unusually Coordinated Cs Ions The reaction of 18-crown-6, 1,4,7,10,13,16-hexaoxacyclooctadecane, with HgI₂/CsI in methanol yields crystals of [Cs₂(C₁₂H₂₄O₆)][HgI₄]. The compound crystallizes monoclinically, space group P2₁/c, Z = 4, a = 1574.8(3), b = 1067.0(3), c = 1693.2(6) pm, and β = 98.29(3)º. The structure consists of a network made up of two different types of [Cs-(18-crown-6)-Cs]²⁺ cations, interconnected by [HgI₄]^2? anions. The cations form an “anti-sandwich” structure with relatively short Cs ? Cs distances of 382 pm in the first type of cations and a longer distance of 480 pm in the second type of cations.     

„Kationenreiche”︁ Oxide Die Kristallstruktur von Li3InO3

Li₃InO₃ crystallises trigonal, P3 c1, with a = 9.606₄, c = 10.42₀ Å, c/a = 1.064₇, Z = 12 and In₁ in 2(a), In₂: 4(d), In₃: 6(f), and O₁, O₂, O₃, Li₁, Li₂, Li₃ each in 12 (g). According to Li₂^[4]{In□_1/3}O₂ Li₃InO₃ is a “stuffed derivative” of a layer structure of the CdJ₂ type. Calculations of the Madelung Part of Lattice Energy [MAPLE] assure the localisation of Li by X-Ray work and explain why In₂, O₁, O₂, and O₃ depart from “ideal” positions.     

Ein neues Orthovanadat(V): Cs2Na[VO4]

A New Orthovanadate (V): Cs₂Na[VO₄] Colourless single-crystals of Cs₂Na[VO₄] resulted by heating intimate mixtures of CsO_0.52, NaO_0.52 and V₂O₅ (Cs: Na: V = 2.2:1.1:1.0) in tightly closed Ni-tubes. The crystal structure was determined (four-circle diffractometer data), 1341 I_o(hkl), R = 6.23%, R_w = 4.23%, parameters see text. The new orthovanadate(V) crystallizes monoclinic (space group P2₁/m) with a = 839.9(1), b = 624.7(1), c = 614.8(1) pm, β = 92.66(1)° (Guinier-Simon powder data), Z = 2. The Madelung Part of Lattice Energy, MAPLE, and Effective Coordination Numbers, ECoN, these calculated via Mean Fictive Ionic Radii, MEFIR, are discussed.     

Das erste Diniobat mit ‚isolierten’︁ Anionen: KLi4[NbO5]=K2Li8[Nb2O10]

The First Diniobate with ‘Isolated’ Anions: KLi₄[NbO₅]=K₂Li₈[Nb₂O₁₀] [1] . By heating of well ground mixtures of the binary oxides [K₂O, Li₂O, Nb₂O₅, K:Li:Nb=1.1:4.4:1, Pt-tube, 1100°C, 3d] colourless, triclinic single crystals of KLi₄NbO₅ have been prepared for the first time: space group P1 (Nr. 2) with a=816.9(2) pm, b=592.2(2) pm, c=589.7(2) pm, α=121.00(2)º, β=91.78(2)°, γ=99.23(2)°, Z=2. The crystal structure was solved by four-cycle diffractometer data [Mo-Kα , 1386 from 1386 I_o(hkl), R=3.4%, R_w=2.6%], parameters see text. Characteristic for this structure are “isolated” groups of [Nb₂O₁₀] and the tetrahedral coordination of Li(1), Li(2), and Li(3). Li(4) has a tetragonal-pyramidal coordination. The structural relations are deduced by Schlegel Diagrams. The Madelung Part of Lattice Energy, MAPLE, the Effective Coordination Numbers, ECoN and the charge distribution have been calculated and discussed.     

Die ersten oligomeren Anionen bei Fluoro-Litho-Metallaten mit Oktaeder-Sandwich-Motiv: Cs4K{[F3MIIIF3]Li[F3MIIIF3]}, MIII = Ga,Fe [1]

The First Oligomeric Anions of Fluoro-Litho Metallates with Octahedra Sandwich Motive: Cs₄K{[F₃M^IIIF₃]Li[F₃M^IIIF₃]}, M^III = Ga, Fe Colourless single crystals of Cs₄K{Li[Ga₂F₁₂]} ( A ) and Cs₄K{Li[Fe₂F₁₂]} ( B ) have been obtained by solid state reaction from intimate mixtures of the corresponding binary fluorides (Pt-tube, 750°C, 40 d). The trigonal unit cells with ( A ) a = 631,3(1)pm; c = 3059,9(6)pm and ( B ) a = 635,0(1)pm; c = 3089,2(7)pm, respectively (Z = 3, Guinier-Simon data, Cu-Kα₁), are confirmed by single crystal investigations. The compounds crystalize isostructural in the space group R3 m (No. 166). The structures were determined using four-circle diffractometer data (Siemens AED 2) with ( A ) R = 2.95%, 3627 I_o and ( B ) R = 1.86%, 4179 I_o, respectively (SHELX-76), and are characterized by triplets of facesharing octahedra parallel [00.1] with the cation-sequence M^III? Li? M^III, six of which are connected by [KF₆]-octahedra via common corners and each triplet is surrounded by six different [KF₆]-octahedra. The structure is completed by Cs⁺ filling the cavities. The Madelung Part of Lattice Energy (MAPLE), Mean Fictive Ionic Radii (MEFIR) and Effective Coordination Numbers (ECoN) are calculated and compared. The classification as lithometallate could be verified by a new MAPLE concept. The Charge Distribution (CHARDI) was calculated and compared with the results according to ‘bond length-bond strength’.     

Das erste zweikernige Oxoferrat(II): „Cs2K4[O2FeOFeO2]”︁

The First Binuclear Oxoferrate(II): ?Cs₂K₄[O₂FeOFeO₂]”? For the first time ?Cs₂K₄[Fe₂O₅]”? was obtained by annealing intimate mixtures of Cs₂O, K₂O, and CsFeO₂ (molar ratio Cs : K : CsFeO₂ 1.3 : 2.1 : 1) in a closed Fe-cylinder (74 d; 470°C) in the form of red single crystals. The structure determination (four-circle diffractometer, MoKα , 760 out of 857 I_o(h kl); R = 5.8%, R_w = 4.6%) confirms the space group C2/m; a = 707.4, b = 1138.5, c = 699.7 pm, β = 91.76°, Z = 2. Essential part of the structure is the binuclear, planar [O(1)₂Fe? O(2)? FeO(1)₂]^6? group which is for the first time observed with oxoferrates(II). Despite different space groups the crystal structure is related to that of Rb₂Na₄[Co₂O₅].     

Eine ‚Reduktive Austausch-Reaktion’︁: Einkristalle von Rb2[MnO4] aus Li[MnO4]

A ‘Reductive Exchange Reaction’: Single Crystals of Rb₂[MnO₄] from Li[MnO₄] By heating of well ground mixtures of the oxides RbO_0.9 and Li[MnO₄] (Rb:Mn = 1.5:1; Ag-tubes; 660°C, 56 d) dark-green, orthorhombic single-crystals of Rb₂[MnO₄] were obtained. The structural determination revealed the isotype to K₂[MnO₄]; a β-K₂SO₄-typ. Thus, for the first time by a pure solid-state-chemical way, via a reductive, complete alkali-metal exchange, single crystals of an oxomanganate(VI) of the alkali metals were prepared. The Madelung Part of the Lattice Energy, MAPLE, and the charge distribution were calculated.     

Über Oxoferrate mit „isolierten”︁ Anionen. Zur Kenntnis von Na8Fe2O7

On Oxoferrato with “isolated” Anions: Na₈Fe₂O₇ Na₈Fe₂O₇ has been prepared by heating of Na₂O and Fe₂O (Na:Fe = 4.6:1, sealed Ag-cylinders, 600°C, 7d) in from of yellow transparent single crystals [monoclinic, P2₁/c (No. 14); a = 8.70₃, b = 11.01₀, c = 10.09₆ Å, β = 107.6°; Z = 4; 4420 independent reflections, R = 0.063] which are isotypic with Na₈Ga₂O₇. The bonding angle Fe? O? Fe within an “isolated” group [Fe₂O₇] is extraordinary small (119.7°). Effective Coordination Numbers, ECoN (these by means of Mean Fictive Ionic Radii, MEFIR), and the Madelung Part of Lattice Energy, MAPLE, are calculated and discussed.     

Ein Oxostannat neuen Strukturtyps: Cs4[SnO4]

An Oxostannate of a New Structure Type: Cs₄[SnO₄] In order to prepare Cs₃LiSnO₄ by heating of a well ground mixture of the binary oxides [CsO_0.67, Li₂O, SnO₂; Cs:Li:Sn = 3.3:1.0:1.0; 450°C; 28 d; Ni-tube] colourless, monoclinic single crystals of Cs₄[SnO₄] have been yielded for the first time: space group P2₁/c with a = 1180.8 pm. b = 728.2 pm, c = 1166,7 pm, β = 111.79°, Z = 4. The crystal structure was solved by fourcycle-diffractometer data [Siemens AED2, 2299 from 2708 I₀(hkl), R = 7.0%, R_w = 5.6%], parameters see text. Characteristic for the complicated structure are “isolated” [SnO₄]^4? tetrahedra. Mean Fictive Ionic Radii, MEFIR, Effective Coordination Numbers, ECoN and the Madelung Part of Lattice Energy, MAPLE, have been calculated.     

Cs10Tl6SiO4, Cs10Tl6GeO4, and Cs10Tl6SnO3 – First Oxotetrelate Thallides,Double Salts Containing “Hypoelectronic” [Tl6]6– Clusters

Cs₁₀Tl₆TtO₄ (Tt = Si, Ge) and Cs₁₀Tl₆SnO₃ were synthesized by the reaction of appropriate starting materials at 623–673 K, followed by fast cooling or quenching to room temperature, in arc‐welded tantalum ampoules. According to single‐crystal X‐ray analyses, the compounds crystallize in new structure types (Cs₁₀Tl₆TtO₄ (Tt = Si, Ge), P2₁/c and Cs₁₀Tl₆SnO₃, Pnma), consisting of [Tl₆]^6– clusters, which can be characterized as distorted octahedra compressed along one of the fourfold axes of an originally unperturbed octahedron, and [SiO₄]^4–, [GeO₄]^4– or [SnO₃]^4– anions. The oxotetrelate thallides can be regarded as “double salts”, which consist of Cs₆Tl₆ on one side and respective oxosilicates, ‐germanates and ‐stannates on the other, showing almost not any direct interaction between the two anionic moieties, as might be expressed e.g. by the formula [Cs₆Tl₆][Cs₄SiO₄]. In contrast to the silicon and germanium compounds, where the oxidation state of the tetrel atom is unambiguously 4+, for the threefold coordinated tin atom in Cs₁₀Tl₆SnO₃ an oxidation state of 2+ has to be assumed. Thus, the latter reveal further evidence that the so called “hypoelectronic” [Tl₆]^6– cluster does not require additional electrons and is intrinsically stable. The distortion of [Tl₆]^6– can be understood in terms of the Jahn–Teller theorem. According to magnetic measurements all title compounds are diamagnetic.