Neue Kronenether‐stabilisierte Oxoniumhalogenochalkogenate: [H3O(Dibromo‐benzo‐18‐Krone‐6)]2[Se3Br10] und [H5O2(Bis‐dibromo‐dibenzo‐24‐Krone‐8]2[Se3Br8]

Novel Oxonium Halogenochalcogenates Stabilized by Crown Ethers: [H₃O(Dibromo‐benzo‐18‐crown‐6)]₂[Se₃Br₁₀] and [H₅O₂(Bis‐dibromo‐dibenzo‐24‐crown‐8]₂[Se₃Br₈] Two novel complex oxonium bromoselenates(II,IV) and –(II) are reported containing [H₃O]⁺ and [H₅O₂]⁺ cations coordinated by crown ether ligands. [H₃O(dibromo‐benzo‐18‐crown‐6)]₂[Se₃Br₁₀] ( 1 ) and [H₅O₂(bis‐dibromo‐dibenzo‐24‐crown‐8]₂[Se₃Br₈] ( 2 ) were prepared as dark red crystals from dichloromethane or acetonitrile solutions of selenium tetrabromide, the corresponding unsubstituted crown ethers, and aqueous hydrogen bromide. The products were characterized by their crystal structures and by vibrational spectra. 1 is triclinic, space group (Nr. 2) with a = 8.609(2) Å, b = 13.391(3) Å, c = 13.928(3) Å, α = 64.60(2)°, β = 76.18(2)°, γ = 87.78(2)°, V = 1404.7(5) ų, Z = 1. 2 is also triclinic, space group with a = 10.499(2) Å, b = 13.033(3) Å, c = 14.756(3) Å, α = 113.77(3)°, β = 98.17(3)°, γ = 93.55(3)°. V = 1813.2(7) ų, Z = 1. In the reaction mixture complex redox reactions take place, resulting in (partial) reduction of selenium and bromination of the crown ether molecules. In 1 the centrosymmetric trinuclear [Se₃Br₁₀]^2? consists of a central Se^IVBr₆ octahedron sharing trans edges with two square planar Se^IIBr₄ groups. The novel [Se₃Br₈]^2? in 2 is composed of three planar trans‐edge sharing Se^IIBr₄ squares in a linear arrangement. The internal structure of the oxonium‐crown ether complexes is largely determined by the steric restrictions imposed by the aromatic rings in the crown ether molecules, as compared to complexes with more flexible unsubstituted crown ether ligands.     

Synthesen zweizähniger P‐Donor/Sn‐Akzeptor‐Liganden: Koordinationsstudien mit Cp*Rh(CO)2 und CpRh(C2H4)2

Alternative Ligands. XXXV. Syntheses of Bidentate P‐Donor/Sn‐Acceptor Ligands: Coordination Experiments with Cp*Rh(CO)₂ and CpRh(C₂H₄)₂ Donor/acceptor ligands Me₂Sn(CH₂CH₂PMe₂)₂ ( 1 ) and Me₂Sn(OCH₂PMe₂)₂ ( 2 ) have been prepared by radical reaction of Me₂PVi with Me₂SnH₂ and by substitution of chlorine in Me₂SnCl₂ or of ethoxy groups in Me₂Sn(OEt)₂ by MOCH₂PMe₂ (M = Li, Na) and HOCH₂PMe₂, respectively. 2 cannot be isolated in pure form from the product mixture because, due to condensation reactions, the “ladder structure” [Me₂Sn(OCH₂PMe₂)₂OSnMe₂]₂ ( 3 ) is formed. The molecular structure of 3 was determined by X‐ray diffraction studies of single crystals. Attempts to produce the thiophosphoryl derivative of 3 result in the degradation of the ladder structure giving the thermally labile phosphane sulfide Me₂Sn(OCH₂P(S)Me₂)₂. Ligands 1 and 2 besides Me₂PCH₂CH₂SnMe₃ ( 4 ) have been used for the preparation of rhodium(I) complexes from Cp*Rh(CO)₂ ( 5 ) or CpRh(C₂H₄)₂ ( 10 ) as educts. The thermal reaction of 5 with 4 yields Cp*Rh(CO)PMe₂CH₂CH₂SnMe₃ ( 6 ), that of 5 with 1 a mixture of the mononuclear derivative Cp*Rh(CO) · PMe₂CH₂CH₂SnMe₂CH₂CH₂PMe₂ ( 7 ) and the binuclear complex [Cp*Rh(CO)PMe₂CH₂CH₂]₂SnMe₂ ( 8 ). The related system [Cp*Rh(CO)PMe₂CH₂O]₂SnMe₂ produced by reaction of 5 with 2 can only be detected in solution but, because of some side‐products, was not fully characterized. From 10 and 4 a mixture of mono‐ and disubstituted products, CpRh(C₂H₄)PMe₂CH₂CH₂SnMe₃ ( 11 ) and CpRh(PMe₂CH₂CH₂SnMe₃)₂ ( 12 ), is obtained. Reaction of 1 with 10 yields a mixture of the complexes CpRh(C₂H₄)PMe₂CH₂CH₂SnMe₂CH₂CH₂PMe₂ ( 13 ) and CpRh(Me₂CH₂CH₂)₂SnMe₂ ( 14 ). Some of the NMR data (¹³C, δδ_Sn) of 14 can be interpreted in terms of the expected Rh → Sn interaction. A definite proof by X‐ray diffraction on single crystals, so far, was not possible.     

Neue Rhodium(I)‐Komplexe mit Donor/Akzeptor‐Chelatliganden

Alternative Ligands. XXXVI. Novel Rhodium(I) Complexes with Donor/Acceptor Chelating Ligands In order to generate metal base/Lewis‐acid interactions in rhodium(I) phosphane complexes the binuclear complex [Rh(CO)₂Cl]₂ was reacted in benzene with dipod ligands of the type R₂M′(OCH₂PMe₂)_x(CH₂CH₂PMe₂)_2–x (R = F, Me; M′ = Si, Ge; x = 0–2) using the Ziegler dilution principle with the aim to produce mononuclear compounds in which with formation of five‐membered chelate rings in principle Rh → M′ contacts are possible. The reactions of ligands 1 – 7 (Table 1) with [Rh(CO)₂Cl]₂ proceed under CO elimination and, in spite of large turnovers, lead to a variety of products 8 – 14 (Table 1), in case of 11 , 13 and 14 accompanied by degradation of the corresponding ligands. Intact ligands are present in the 16‐membered rings of the binuclear complexes 8 – 10 and 12 , for which, due to the molecular structure, Rh → M′ interactions can be excluded. In the reaction of Me₂Si(OCH₂PMe₂)₂ ( 4 ) with [Rh(CO)₂Cl]₂ the unusual binuclear system 11 with a central Rh₂O₂ four‐membered ring and two RhO(SiMe₂OCH₂PMe₂) six‐membered rings is formed. Small amounts of the mononuclear compounds Rh(CO)Cl(Me₂PCH₂OH)₂ ( 13 ) and Rh(CO)Cl₃(Me₂PCH₂OH)₂ ( 14 ), respectively, are obtained in crystalline form from the reaction mixtures of [Rh(CO)₂Cl]₂ with Me₂Ge(OCH₂PMe₂)(CH₂CH₂PMe₂) ( 6 ) or Me₂Ge(OCH₂PMe₂)₂ ( 7 ). The new complexes were characterized by analytic (C, H), spectroscopic (NMR, IR, MS) and, except for 12 , by single crystal structural analyses.     

Trifluoromethyl phosphaalkenes of the type F3CPC(OR)NR2: Synthesis,spectroscopic investigations,and ligand properties [1]

The one-pot reaction of the alcohol adducts F₃CP(H)CF₂OR of perfluoro-2-phosphapropene with secondary amines in a 1:3 molar ratio affords the stable phosphaalkenes F₃CPC(OR)NR₂ (R = Me, Et) 1–4 in yields of 58%. NMR and He(I) PE spectroscopic investigations show that the lone pair electrons on nitrogen and oxygen participate in n/π conjugation. In contrast to typical low-coordinated double bonds the new derivatives do not react with alcohols, amines, and 1,3-dienes. The derivatives are more closely related to the phosphaalkenes F₃C(F)NR₂ than to perfluoro-2-phosphapropene. The reaction of F₃C(OEt)NMe₂ ( 3 ) with Cr(CO)₅THF yields the η¹(P) complex Cr(CO)₅[F₃CPC(OEt)NMe₂] ( 7 ) with an unusually long sp² PC bond (1.809 Å).     

Reactions of iPr2N?CP with methylating agents: Formation of the diamino-2-phosphaallylic cation ⊕

The reaction of di(isopropyl)aminophosphaethyne 1 with iodomethane or the methyl ester of trifluormethylsulfonic acid (methyl triflate) yields the ionic 1λ³, 3λ³-diphosphetene derivatives ⁺ X⁻ ( 2a : X = I; 2b : X = CF₃SO₃). On the basis of NMR spectroscopic and X-ray diffraction studies, the cation can be described as a combination of an amino-2-phosphaallylic cation and its methylated derivative.