Diborheterocyclen: Oxadiborolan – Oxadiborinan – Diazadiborinan

Diboron Heterocyclic Compounds: Oxadiborolane – Oxadiborinane – Diazadiborinane The diboryl compounds R(Cl)B(CH₂)_nB(Cl)R (R ? Cl or CH₃; n = 2, 3) and the silylated or stannylated starting materials [(CH₃)₃Y]₂X (Y ? Si or Sn; X ? S, NCH₃, O, NCH₃? NCH₃) were used for (5+1)- and (4+2)-cyclocondensation reactions. Dimethylether was an additional starting molecule. While no thiadiborinanes could be isolated, the nitrogen or oxygen containing heterocycles were formed in varying yields. Synthesis and properties of these compounds are described.     

Variationen modulo 4–4+, 4+3–3+4–, 4–5+, 5–4+4–5+4–4+ bei Seltenerdcarbidhalogeniden

The new compounds Pr₈(C₂)₄Cl₅ (1), Pr₁₄(C₂)₇Cl₉ (2), Pr₂₂(C₂)₁₁Cl₁₄ (3), Ce₂(C₂)Cl (4), La₂(C₂)Br (5), Ce₂(C₂)Br (6), Pr₂(C₂)Br (7), Ce₁₈(C₂)₉Cl₁₁ (8), and Ce₂₆(C₂)₁₃Cl₁₆ (9) were prepared by heating mixtures of LnX₃, Ln and carbon or in an alternatively way LnX₃, and “Ln₂C_3–x” in appropriate amounts for several days between 750 and 1200 °C. The crystal structures were investigated by X‐ray powder analysis (5–7) and/or single crystal diffraction (1–4, 8, 9). Pr₈(C₂)₄Cl₅ crystallizes in space group P2₁/c with the lattice parameters a = 7.6169(12), b = 16.689(2), c = 6.7688(2) Å, β = 103.94(1) °, Pr₁₄(C₂)₇Cl₉ in Pc with a = 7.6134(15), b = 29.432(6), c = 6.7705(14) Å, β = 104.00(3) °, Pr₂₂(C₂)₁₁Cl₁₄ in P2₁/c with a = 7.612(2), b = 46.127(9), c = 6.761(1) Å, β = 103.92(3) °, Ce₂(C₂)₂Cl in C2/c with a = 14.573(3), b = 4.129(1), c = 6.696(1) Å, β = 101.37(3) °, La₂(C₂)₂Br in C2/c with a = 15.313(5), b = 4.193(2), c = 6.842(2) Å, β = 100.53(3) °, Ce₂(C₂)₂Br in C2/c with a = 15.120(3), b = 4.179(1), c = 6.743(2) Å, β = 101.09(3) °, Pr₂(C₂)₂Br in C2/c with a = 15.054(5), b = 4.139(1), c = 6.713(3) Å, β = 101.08(3) °, Ce₁₈(C₂)₉Cl₁₁ in P$\bar{1}$ with a = 6.7705(14), b = 7.6573(15), c = 18.980(4) Å,α = 88.90(3) °, β = 80.32(3) °, γ = 76.09(3) °, and Ce₂₆(C₂)₁₃Cl₁₆ in P2₁/c with a = 7.6644(15), b = 54.249(11), c = 6.7956(14) Å, β = 103.98(3) ° The crystal structures are composed of Ln octahedra centered by C₂ dumbbells. Such Ln₆(C₂)‐octahedra are condensed into chains which are joined into undulated sheets. In compounds 1–4 three and four up and down inclined ribbons alternate (4₊4_–, 4₊3_–3₊4_–, 4₊4_–3₊4_–4₊3_–), in compounds 8 and 9 four and five (4₊5_–, 5₊4_–4₊5_–4₊4_–), and in compounds 4–7 one, one ribbons (1₊1_–) are present. The Ln‐(C₂)‐Ln layers are separated by monolayers of X atoms.     

Synthesis and Reactivity of 2,2,4,4–Tetrakis(tri–tert–butoxysilanethiolato)–1,3,2,4–dithiadistannetane – Crystal and Molecular Structures of Two Polymorphic Forms

The title compound, [Sn(μ–S){SSi(O^tBu)₃}₂]₂ ( 1 ), containing four–coordinated tin(IV), crystallizes in two polymorphic modifications. The orthorhombic 1a –form has been obtained in the reaction of (^tBuO)₃SiSH and Et₃N with SnCl₂, whereas the triclinic 1b –form in the reaction with SnCl₄ as substrate. The crystal and molecular structures of both polymorphs ( 1a as a redetermination) have been determined by a single–crystal X–ray diffraction study at room temperature. The title compound was shown to react with ammonia and ammonia complexes of some d–block metal cations giving products of Sn–S bond cleavage.     

Darstellung,Kristallstrukturen und Schwingungsspektren von Verbindungen mit den linearen Dipnictidoborat(3–)‐Anionen [P–B–P]3–, [As–B–As]3– und [P–B–As]3–

Synthesis, Crystal Structure, and Vibrational Spectra of Compounds with the Linear Dipnictidoborate (3–) Anions [P–B–P]^3–, [As–B–As]^3–, and [P–B–As]^3– The alkali metal boron compounds M₃[BX₂] with X = P, As are synthesized from the alkali metals M and the binary components MX or M₄X₆ and BX in sealed steel ampoules (phosphides) or niobium ampoules (arsenides) at 1000 K. The compounds are obtained as bright yellow prisms (M₃[BP₂]) or plates (K₂Na[BP₂]) and yellow‐red prismatic crystals (M₃[BAs₂], Cs₃[BPAs]) which are very sensitive against oxidation and hydrolysis. Three different structure types are formed, namely K₂Na[BP₂] (C2/m (No. 12); Z = 4; a new mC24 structure type); Na₃[BP₂] (P2₁/c (No. 14); Z = 4, β‐Li₃[BN₂] type), M₃[BX₂] with M = K, Rb, Cs and X = P, As and Cs₃[P–B–As] (C2/c, (No. 15); Z = 4, K₃[BP₂] type). The bond lengths of the linear [BX₂]^3– anions are hardly changed and correspond to a Pauling bond order PBO = 1.9 (d(B–P) = 176.7–177.1 pm; d(B–As) = 186.5–188.0 pm). The vibrational spectra confirm the existence of unmixed and mixed units [P–B–P]^3–, [As–B–As]^3– and [P–B–As]^3– with D_∞h and C_∞v symmetry, respectively. The valence force constants f(B–X) and the corresponding Siebert bond orders, calculated from the frequencies, are discussed and compared with those of the isoelectronic anions and molecules.     

Synthesis,Crystal Structure,and Ultraviolet–Visible Spectrum of 8–Substituted–10,10–Dimethyl–10H–pyrido[1,2–a]indolium Perchlorates–Containing Thienyl Moiety

Two novel compounds, 8–[2–(2–thienyl)vinyl]–10,10–dimethyl–10H–pyrido[1,2–a] indolium perchlorate ( 3a ) and 8–[2–(5–phenyl–2–thienyl)vinyl]–10,10–dimethyl–10H–pyrido[1,2–a]indolium perchlorate ( 3b ) were synthesized and characterized by IR, ¹H–NMR, elemental analyses, and X–ray diffraction. Crystal structural analysis suggested that either 3a or 3b exhibited good coplanarity and rings and vinyl in the target molecule could make up a large conjugated system. Ultraviolet–visible absorption analysis indicated both 3a and 3b possessed large maximum absorptions, and 3b underwent a significant redshift (43.0 nm) in comparison with 3a .