Beiträge zur Strukturchemie phosphorhaltiger Ketten und Ringe. 1. Die KristallStruktur des Diphosphasilirans (t-BuP)2SiPh2

Structural Chemistry of Phosphorus-containing Chains and Rings. 1. Crystal Structure of the Diphosphasilirane (t-BuP)₂SiPh₂ The three-membered P₂Si-heterocycle 1, 2-di-tert-butyl-3, 3-diphenyl-1, 2, 3-diphosphasilirane (t-BuP)₂SiPh₂ crystallizes monoclinic in the space group P2₁ with a = 1041.2 pm, b = 882.3 pm, c = 1158.1 pm, β = 91.33° and Z = 2 formula units. A special structural feature is the regular triangle built up by two P and one Si. Therefore the endocyclic bond angle at Si is as low as 60°. The average bond lengths are P? P = 222.6 pm, P? Si = 222.5 pm, P? C = 190.8 pm, Si? C = 186.6 pm, (C? C )ph = 139.0 pm, ( C? C )_t-Bu = 151.7 pm. The geometry of the substituents phenyl and tert-butyl is quite normal, the last ones are slightly disordered.     

Beiträge zur Strukturchemie phosphorhaltiger Ketten und Ringe. 7. Die Kristall- und Molekülstruktur des Diphosphagermetans (t-BuP)2(GePh2)2

Structural Chemistry of Phosphorus Containing Chains and Rings. 7. Molecular and Crystal Structure of the Diphosphagermetane (t-BuP)₂(GePh₂)₂ The compound 1,2-di-tert-butyl-3,3,4,4-tetraphenyl-diphospha-3,4-digerma-cyclobutan, (t-BuP)₂(GePh₂)₂, crystallizes monoclinically in the space group P2₁/c with a = 996.8 pm, b = 1337.3 pm, c = 2403.4 pm, β = 92.66° and Z = 4 formula units. The main structural feature is a non-planar four-membered ring. The (average) bond lengths are d(Ge? Ge) = 242.1 pm, d(Ge? P) = 234.0 pm, d(P? P) = 221.6 pm, d(Ge? C) = 194.9 pm, d(P? C) = 188.tyl4 pm, d(C? C)_Ph = 136.l5 pm, d(C? C)_t-Bu = 151.8 pm, d(C? H)_Ph = 91 pm, d(C? H)_t-Bu ? 95 pm. The geometry of the substituents phenyl and tert-butyl is quite normal.     

Beiträge zur Chemie des Phosphors. 101. Synthese und Eigenschaften von Diphosphaboriranen (t-BuP)2BNR2 und (t-BuP)2BNR1R2

Contributions to the Chemistry of Phosphorus. 101 Synthesis and Properties of Diphosphaboriranes (t-BuP)₂BNR₂ and (t-BuP)₂BNR¹R² The reaction of K(t-Bu)P? P(t-Bu)K with diorganylaminodichloroboranes under suitable conditions leads to the new 1,2-di-tert-butyl-3-diorganylamino-1,2,3-diphosphaboriranes (-1,2-diphospha-3-boracyclopropanes) (t-BuP)₂BNR₂ ( 2 , 7 ) and (t-BuP)₂BNR¹R² ( 3 — 6 ), respectively. The P₂B three-membered heterocycles 2 — 5 can be isolated in good yields. They are relatively stable against dimerization to the corresponding phosphorus boron six-membered ring compounds with opposite boron atoms. The rate of dimerization depends on steric and electronic influences of the substituents at the three-membered ring. All NMR spectroscopic results are only consistent with a structure in which the B and N atoms show planar coordination and are connected by a partial double bond.     

Beiträge zur Strukturchemie phosphorhaltiger Ketten und Ringe. 11. Die Kristall- und Molekülstrukturen der beiden Konfigurationisomeren des Tetraphospha-silaspiro[2.2]pentans (PBut)2Si(PBut)2

Structural Chemistry of Phosphorus Containing Chains and Rings. 11. Crystal and Molecular Structures of the Two Stereoisomers of Tetraphospha-silaspiro[2.2]pentane (PBu^t)₂Si(PBu^t)₂ The spirocyclic compound 1,2,4,5-tetra-tert-butyl-1,2,4,5-tetraphospha-3-silaspiro[2.2]pentane exists in tow diastereomers of point symmetry 4 and 2. The isomer with symmetry 4 even in the solid crystallizes tetragonally in I4₁/a with a = 1247.0, c = 1505.5 pm and Z = 4. The isomer of fairly exact symmetry 2 crystallizes triclinically in P1 with a = 612.8, b = 996.3, c = 1017.2 pm, α = 75.63, β = 72.38, γ = 88.71° and Z = 1. In this disordered structure the surroundings of Si is slightly distorted due to the influence of the substituents. The (average) bond lengths are (4 , 2): d(Si? P) = 220.09(9), 221.5(5); d(P? P) = 225.5(2), 224.2(5); d(P? C) = 189.4(3), 190(2); d(C? C) = 151.4(4), 152(3) pm. The geometry of the substituents in both isomers is quite normal.     

Beiträge zur Chemie des Phosphors. 224. Zur Thermolyse von 1,2-Di-tert-butyldiphosphan, 1,2,3-Tri-tert-butyltriphosphan und Tetra-tert-butylcyclotetraphosphan

Contributions to the Chemistry of Phosphorus. 224. On the Thermolysis of 1,2-Di-tert-butyldiphosphane, 1,2,3-Tri-tert-butyltriphosphane, and Tetra-tert-butylcyclotetraphosphane On disproportionation of 1,2-di-tert-butyldiphosphane, H(t-Bu)P? P(t-Bu)H (1) , 1,2,3-tri-tert-butyltriphosphane, H₂(t-BuP)₃ (2) , is formed which reacts further at temperatures above 100°C to give 1-(tert-butylphosphino)-2,3,4-tri-tert-butylcyclotetraphosphan, P₅(t-Bu)₄H (4) . Compound 4 reacts with 1 or 2 with lengthening of the P-sidechain to furnish the corresponding 1-(1,2-di-tert-butyldiphosphino)-2,3,4-tri-tert-butylcyclotetraphosphane, P₆(t-Bu)₅H (5) . At temperatures above 170°C, 5 disproportionates into the tetra-tert-butylcyclotetraphosphane, (t-BuP)₄ (3) which is stable up to about 200°C, and the bicyclo[3.1.0]hexaphosphane P₆(t-Bu)₄ from which the polycyclophosphanes P₉(t-Bu)₃ and P₈(t-Bu)₆ arise during the further course of the thermolysis. These products are finally converted through even more phosphorus-rich and more highly condensed t-butylcyclophosphanes into elemental phosphorus. In each reaction step, varying amounts of the monophosphane derivatives t-BuPH₂, (t-Bu)₂PH, and (t-Bu)₃P are formed. The proposed course of the reaction is further substantiated by the pyrolysis products of pure 2 and 3 .     

Beiträge zur Chemie des Phosphors. 160. Zur Ringspaltung der Phosphor-Dreiringheterocyclen (t-BuP)2CMe2 und (t-BuP)2N(i-Pr) mit Kalium bzw. K-Naphthalid

Contributions to the Chemistry of Phosphorus. 160. About the Ring Cleavage of the Phosphorus Three-Membered Heterocycles (t-BuP)₂CMe₂ and (t-BuP)₂N(i-Pr) with Potassium or K-Naphthalenide The reaction of (t-BuP)₂CMe₂ with potassium or K-naphthalenide in tetrahydrofuran or 1,2-dimethoxyethane mainly leads to the symmetric phosphide K(t-Bu)P? ;CMe₂? ;P(t-Bu)K ( 1 ) via P? ;P-bond cleavage. Above —78°C 1 decomposes into the monophosphides KHP(t-Bu) ( 3 ) and KP(t-Bu)(i-Pr) ( 4 ). In the case of (t-BuP)₂N(i-Pr) under analogous conditions essentially the P? ;N-bond is split up yielding the phosphide K(t-Bu)P? ;P(t-Bu)? ;NH(i-Pr) ( 5 ), which is stable at room temperature. Contrary to (t-BuP)₂BN(i-Pr)₂ cyclic phosphides are not formed. The different reactive behavior in the metalation of phosphorus three-membered heterocycles of the type (PR¹)₂ER (E = hetero atom) is discussed.     

Beiträge zur Chemie des Phosphors. 106. Synthese und Eigenschaften des Diphosphacyclopropans (t-BuP)2CHMe

Contributions to the Chemistry of Phosphorus. 106. Synthesis and Properties of the Diphosphacyclopropane (t-BuP)₂CHMe The new 1,2-di-tert-butyl-3-methyl-1,2-diphosphacyclopropane (1,2-di-tert-butyl-3-methyl-diphosphirane), (t-BuP)₂CHMe ( 1 ), is obtained by reacting K(t-Bu)P? P(t-Bu)K with 1,1-dichloroethane under suitable conditions. 1 can be isolated by high vacuum distillation and is stable for months when stored under inert gas at room temperature. Particularly, no dimerization to the corresponding 1,2,4,5-tetraphosphacyclohexane takes place. The NMR parameters indicate an increase of the exocyclic bond angles compared to (t-BuP)₂CH₂. The signs of all CP coupling constants have been determined by spin tickling experiments. The ²J(CCP)-coupling of the methyl group at the ring carbon depends strongly on the dihedral angle.     

Phosphaniminato-Komplexe des Schwefels. Synthese und Kristallstrukturen von [O3SS(NPPh3)2] · CH3CN, [SO(NPPh3)2] und [SCl(NPMe3)2]Cl

Phosphorane Iminato Complexes of Sulfur. Syntheses and Crystal Structures of [O₃SS(NPPh₃)₂] · CH₃CN, [SO(NPPh₃)₂], and [SCl(NPMe₃)₂]Cl The title compounds have been prepared by the reaction of Me₃SiNPPh₃ with SO₂ and SOCl₂, respectively, and by the reaction of Me₃SiNPMe₃ with S₂Cl₂. They form colourless, moisture sensitive crystals, which were characterized by IR spectroscopy and by crystal structure determinations. [O₃SS((NPPh₃)₂)] · CH₃CN : Space group Pca2₁, Z = 4, structure solution with 4016 observed unique reflections, R = 0.050. Lattice dimensions at ?60°C: a = 1865.1, b = 1168.4, c = 1569.0 pm. The compound has a zwitterionic structure with a S? S bond length of 218.2 pm and bond lengths S? N of 161.2 and P? N of 160.1 pm. [SO(NPPh₃)₂] : Space group P2₁/c, Z = 4, structure solution with 2854 observed unique reflections, R = 0.113. Lattice dimensions at ?50°C: a = 1173.1, b = 1585.6, c = 1619.2 pm, b? = 98.13°. The compound forms monomeric molecules, in which the positions of S and N atoms are disordered in two positions. The bond lengths are S? N 166 pm and P? N 163 pm in average. [SCl(NPMe₃)₂]Cl : Space group P1 , Z = 2, structure solution with 2416 observed unique reflections, R = 0.038. Lattice dimensions at 20°C: a = 613.2, b = 1030.3, c = 1111.4 pm, α = 88.48°, b? = 88.01°, γ = 83.10°. The compound forms ions [SCl(NPMe₃)₂]⁺ and Cl^?. In the cation the sulfur atom is ?-tetrahedrally coordinated with a long S? Cl distance of 246.9 pm and bond lengths S? N of 155.3 pm and P? N of 164.3 pm in average.     

Übergangsmetallphosphidokomplexe. VIII. Strukturuntersuchungen an Übergangsmetallphosphor-Vier- und Sechsringkomplexen. Die Strukturen von [(CO)4MnPH2]2, [(CO)4MnPH2]3 und [cpNiPH2]3

Transition Metal Phosphido Complexes. VIII. X-Ray Diffraction Studies of Transition Metal Phosphorus Four- and Six-Membered Ring Complexes. Structures of [(CO)₄MnPH₂]₂, [(CO)₄MnPH₂]₃, and [cpNiPH₂]₃ [(CO)₄MnPH₂]₂ 1 crystallizes triclinic in the space group P1 with a = 680.4 pm, b = 706.4 pm, c = 919.1 pm, α 110.5°, β = 91.92°, γ 115.65°, and Z = 1 formula unit. The molecule exhibits a centrosymmetrical structure. The bond angles within the planar four-membered (Mn? P)₂-ring are 76.1° at the Mn atoms and 103.9° at the P atoms, respectively. The average Mn? P bond distance is found to be 235.1 pm. [(CO)₄MnPH₂]₃ 2 crystallizes monoclinic in the space group P2/n with a = 905.2 pm, b = 974.8 pm, c = 1264.2 pm, β = 109.1°, and Z = 2 formula units. The framework of the six-membered (Mn? P)₃-ring can be described as having a twist boat conformation. The average endocyclic bond angles are with 89.1° at the Mn atoms and 130.1° at the P atoms, respectively, largely widened compared to 1 . The average Mn? P bond distance, which is found to be 238.5 pm, is also slightly increased compared to 1 . [cpNiPH₂]₃ 3 crystallizes rhombohedral in the space group R3. The cell constants (hexagonal setting) are a = b = 1686.1 pm, c = 561.1 pm and Z = 3 formula units. The six-membered (Ni? P)₃-ring exhibits a chair conformation. The endocyclic bond angles are with 92.3° at the Ni atoms and 124.3° at the P atoms, respectively, comparable with those of the six-membered ring compound 2 . The Ni? P bond distance is found to be 215.2 pm. The eyclopentadienyl ligands are disordered and have been refined as rigid groups.     

Beiträge zur Strukturchemie phosphorhaltiger Ketten und Ringe. 16. Die Molekül- und Kristallstruktur des Triisopropyl-undecaphosphans P11(i-Pr)3

Structural Chemistry of Phosphorus Containing Chains and Rings. 16. Molecular and Crystal Structure of the Triisopropylundecaphosphane P₁₁(i-Pr)₃ The compound 4,7,11-triisopropyl-pentacyclo[6.3.0.0^2.6.0^3.10.0^5.9]undecaphosphane, C₉H₂₁P₁₁, crystallizes triclinically in the space group P1 with a = 1 045.3 pm, b = 1 057.2 pm, c = 1 075,0 pm, α = 101.00°, β = 98.89°, γ = 112.27° and Z = 2. The main structural feature is a phosphorus skeleton with approximate symmetry D₃ composed of six five-membered rings which are asymmetrically substituted by the isopropyl groups. The (average) bond lengths are d(P? P) = 221.6 pm, d(P? C) = 187.5 pm, d(C? C) = 151.4 pm, d(C? H) = 108 pm with 217.6 ≤ d(P? P) ≤ 226.4 pm. The geometry of the substituents is quite normal.     

Beiträge zur Chemie des Phosphors. 123. Synthese und Eigenschaften der Diphosphagermirane (t-BuP)2GePh2 und (t-BuP)2GeEt2

Contributions to the Chemistry of Phosphorus. 123. Synthesis and Properties of the Diphosphagermiranes (t-BuP)₂GePh₂ and (t-BuP)₂GeEt₂ The first three-membered P₂Ge heterocycles, 1,2-di-tert-butyl-3, 3-diphenyl-1, 2, 3-diphosphagermirane, (t-BuP)₂GePh₂ (1) , and 1, 2-di-tert-butyl-3, 3-diethyl-1, 2, 3-diphosphagermirane, (t-BuP)₂GeEt₂ (2) , were synthesized by [2+1] cyclocondensation reactions of K(t-Bu)P—P(t-Bu)K with diphenylgermanium dichloride and diethylgermanium dichloride, respectively. The four-, five-, and six-membered cyclogermaphosphanes (t-BuP)₂(GePh₂)₂ (3) , (t-BuP)₃GeR₂ ( 6 R = Ph; 7 R = Et), (t-BuP)₄GePh₂ (5) and (t-BuP)₄(GePh₂)₂ (4) as well as (t-BuP)₄ are formed as by-products. The diphosphagermiranes 1 and 2 could be isolated in 93 and 100% purity, respectively, and were unambiguously characterized as compounds with a cyclic P₂Ge skeleton. The ³¹P-NMR parameters of the cyclogermaphosphanes 3—7 are reported.     

Die Kristallstruktur des tBu2P?PP(Br)tBu2

The Crystal Structure of tBu₂P? P?P(Br)tBu₂ tBu₂P? P?P(Br)tBu₂ 1 crystallizes in the monoclinic space group P2₁/c with a = 2 888.9(3), b = 972.16(10), c = 1 534.04(14) pm, β = 105.129(8)° and 8 formula units in the unit cell. The two independent P₃-units in 1 form angles of 105.77° or 105.98°, resp. One P? P distance (220,4 pm) corresponds to a single bond, the other one (207.9 pm) to a double bond.     

Element-Element-Bindungen. I. Synthese und Struktur des Tetra(tert-butyl)tetrarsetans und des Tetra(tert-butyl)tetrastibetans

Element-Element Bonds. I. Syntheses and Structure of Tetra(tert-butyl)tetrarsetane and of Tetra(tert-butyl)tetrastibetane Dilithium (tert-butyl)arsenide reacts with (tert-butyl)dichloroarsine to give tetra-(tert-butyl)tetrarsetane 1 ; homologous tetra(tert-butyl)tetrastibetane 2 is formed by reduction of (tert-butyl)dichlorostibane with magnesium. The isotypic compounds 1/2 crystallize in the monoclinic space group P2₁/c with Z = 4. The dimensions of the unit cells determined at ?45 ± 5°C are: a = 957.4(8)/1 000.2(3); b = 1 399.1(14)/1 423.9(4); c = 1 697.4(9)/1 749.8(7) pm; β = 96.02(6)/96.77(3)°. As shown by low temperature X-ray structure determinations (3 531/3 232 symmetry independent reflections; R_g = 4.0/4.6%) the four membered rings E₄ (E = As or Sb) are folded; in all-trans configuration the bulky organic substituents occupy pseudo-equatorial positions. Characteristic averaged bond distances and angles are: E? E 244/282; E? C 202/221 pm; ? E? E? E 86/85° ? E? E? C 101/99°. The dihedral angels of the bisphenoides built up by the atoms of the rings are found to be 139/133°.     

Beiträge zur Chemie des Phosphors. 129. Synthese und Eigenschaften der Phospha-germa-cyclobutane (t-BuP)2(GePh2)2 und (t-BuP)3GePh2

Contributions to the Chemistry of Phosphorus. 129. Synthesis and Properties of the Phospha-germa-cyclobutanes (t-BuP)₂(GePh₂)₂ and (t-BuP)₃GePh₂ The phospha-germa-cyclobutanes 1,2-di-tert-butyl-3,3,4,4-tetraphenyl-1,2-diphospha-3,4-digerma-cyclob utane, (t-BuP)₂(GePh₂)₂ ( 1 ), and 1,2,3-tri-tert-butyl-4,4-diphenyl-1,2,3-tri-phospha-4-germa-cyclobutan e, (t-BuP)₃GePh₂ ( 2 ), are obtained as main-products of the cyclocondensation of K(t-Bu)P? P(t-Bu)K with Ph₂GeCl₂ under certain reaction conditions. 1 and 2 could be isolated in the pure state and were clearly characterized as the first four-membered P₂Ge₂ and P₃Ge heterocycles, respectively.     

Beiträge zur Chemie des Phosphors. 104. Synthese und Eigenschaften von 1,3-Dihalogen-1,2,3-tritert-butyltriphosphanen (t-BuP)3X2, X = Cl,Br, I

Contributions to the Chemistry of Phosphorus. 104. Synthesis and Properties of 1,3-Dihalogen-1,2,3-tri-tert-butyltriphosphanes (t-BuP)₃X₂, X = Cl, Br, I The halogenating ring-cleavage of tri-tert-butyl-cyclotriphosphane, (t-BuP)₃, by iodine, bromine or phosphorus(V)bromide as well as phosphorus(V)chloride leads to the first 1,3-dihalogen-1,2,3-triorganyltriphosphanes (t-BuP)₃I₂ ( 1 ), (t-BuP)₃Br₂ ( 2 ), and (t-BuP)₃Cl₂ ( 3 ). The 1,2-dihalogen-1,2-di-tert-butyldiphosphanes (t-BuP)₂I₂ ( 4 ), (t-BuP)₂Br₂ ( 6 ), and (t-BuP)₂Cl₂ ( 9 ) as well as the dihalogen-tert-butylphosphanes t-BuPI₂ ( 5 ), t-BuPBr₂ ( 7 ), and t-BuPCl₂ ( 10 ) are formed as by-products. Moreover, the reaction of (t-BuP)₃ with PBr₅ leads to 1-bromo-2,3,4-tri-tert-butyl-cyclo-tetraphosphane, (t-BuP)₃(PBr) ( 8 ). The compounds 1 and 3 could be isolated in a pure state and were characterized in all details. 3 is a reMarkably stable open-chain triphosphane.     

Synthese und Struktur von Lithium-tris(trimethylsilyl)silanid · 1,5 DME

Synthesis and Structure of Lithium Tris(trimethylsilyl)silanide · 1,5 DME Lithium tris(trimethylsilyl)silanide · 1,5 DME 2a synthesized from tetrakis(trimethylsilyl)silane 1 [6] and methyllithium in 1,2-dimethoxyethane , crystallizes in the monoclinic space group P2₁/c with following dimensions of the unit cell determined at a temperature of measurement of ?120 ± 2°C: a = 1 072.9(3); b = 1 408.3(4); c = 1 775.1(5) pm; β = 107.74(2)°; 4 formula units (Z = 2). An X-ray structure determination (R_w = 0.040) shows the compound to be built up from two [lithium tris(trimethylsilyl)silanide] moieties which are connected via a bridging DME molecule. Two remaining sites of each four-coordinate lithium atom are occupied by a chelating DME ligand. The Li? Si distance of 263 pm is considerably longer than the sum of covalent radii; further characteristic mean bond lengths and angles are: Si? Si 234, Li? O 200, O? C 144, O?O (biß) 264 pm; Si? Si? Si 104°, Li? Si? Si 107° to 126°; O? Li? O (inside the chelate ring) 83°. Unfortunately, di(tert-butyl)bis(trimethylsilyl)silane 17 prepared from di(tert-butyl)dichlorsilane 15 , chlorotrimethylsilane and lithium, does not react with alkyllithium compounds to give the analogous silanide.     

Beiträge zur Chemie des Phosphors. 144. Synthese und Eigenschaften des Hexaphospha-3-germaspiro[2.4]heptans (t-BuP)2Ge(t-BuP)4

Contributions to the Chemistry of Phosphorus. 144. Synthesis and Properties of the Hexaphospha-3-germaspiro[2.4]heptane (t-BuP)₂Ge(t-BuP)₄ The cyclocondensation of K(t-Bu)P? P(t-Bu)K with germanium tetrachloride in the molar ratio of 2:1 yields the novel spirocyclic compound 1,2,4,5,6,7-hexa-tert-butyl-1,2,4,5,6,7-hexaphospha-3-germaspiro[2.4]heptane, (t-BuP)₂Ge(t-BuP)₄ ( 1 ). Besides considerable amounts of (t-BuP)₄ are formed and occasionally some (t-BuP)₃ can be found. 1 could be isolated in the pure state and has been NMR-spectroscopically characterized as a spirocyclic compound with a P₂GeP₄ skeleton.     

Zur Bildung und Struktur der Phosphinophosphiniden-phosphorane tBu2P?PP(Me)tBu2 1, tBu(Me3Si)P?PP(Me)tBu2 2 und tBu2P?PP(Br)tBu2 3

Synthesis and Structure of Phosphinophosphinidene-phosphoranes tBu₂P? P?P(Me)tBu₂ 1, tBu(Me₃Si)P? P?P(Me)tBu₂ 2, and tBu₂P? P?P(Br)tBu₂ 3 A new method for the synthesis of 1 and 2 (Formulae see ?Inhaltsübersicht”?) is reported based on the reaction of 5 with substitution reagents (Me₂SO₄ or CH₃Cl). The results of the X-ray structure determination of 1 and 2 are given and compared with those of 3 . While in 3 one P? P distance corresponds to a double bond and the other P? P distance to a single bond (difference 12.5 pm) the differences of the P? P distances in 1 and 2 are much smaller: 5.28 pm in 1 , 4.68 pm in 2 . Both 1 and 2 crystallize monoclinic in the space group P2₁/n (Z = 4). 2 additionally contains two disordered molecules of the solvent pentane in the unit cell. Parameters of 1 : a = 884.32(8) pm, b = 1 924.67(25) pm, c = 1 277.07(13) pm, β = 100.816(8)°, and of 2 : a = 1 101.93(12) pm, b = 1 712.46(18) pm, c = 1 395.81(12) pm, β = 111.159(7)°, all data collected at 143 K. The skeleton of the three P atoms is bent (PPP angle 100.95° for 1 , 100.29° for 2 and 105.77° for 3 ). Ab initio SCF calculations are used to discuss the bonding situation in the molecular skeleton of the three P atoms of 1 and 3 . The results show a significant contribution of the ionic structure R₂P? P(^?)? P(⁺)(X)R₂. The structure with (partially) charged P atoms is stabilized by bulky polarizable groups R (as tBu) as compared to the fully covalent structure R₂P? P(X)? PR₂.     

Acyl- und Alkylidenphosphane. XXXII [1, 2]. Di-cyclo-hexoyl- und Diadamant-1-oylphosphan — Keto-Enol-Tautomerie und Struktur

Acyl- and Alkylidenephosphines. XXXII. Di-cyclohexoyl- and Diadamant-1-oylphosphine – Keto-Enol Tautomerism and Structure Lithium dihydrogenphosphide · DME (¹) [12] and cyclo-hexoyl or adamant-1-oyl chloride react in a molar ratio of 3:2 to give lithium di-cyclo-hexoylphosphide · DME and the corresponding diadamant-1-oylphosphide.2THF (¹) resp. Treatment of these two compounds with 85% tetrafluoroboric acid. diethylether adduct yields di-cyclo-hexoyl- ( 1b ) and diadamant-1-oylphosphine ( 1c ). In nmr spectroscopic studies 1b over a range of 203 to 343 K, a strong temperature dependence of the keto-enol equilibrium is found; thermodynamic data characteristic for the formation of the enol tautomer (ΔH⁰ = ?4.3 kJ. mol^?1; ΔS⁰ = ?9.2 J. mol^?1. K (^?1) are compared of 1,3-diketones. The enol tautomer of diadamant-1-oylphosphine ( E-1c ) as obtained from a benzene solution in thin colourless plates, crystallizes in the monoclinic space group P2₁/c {a = 722.2(2); b = 1085.5(4); c = 2434.8(5) pm; ß = 96.43(2)° at –100 ± 3°C; Z = 4}. An X- ray structure analysis (R_w = 0.033) shows bond lengths and angles to be almost identical within the enolic system (P? C 179/180; C? O 130/129; C? C(adamant-1-yl) 152/153 pm; C? P? C 99°; P? C? O 124°/124°; P? C? C 120°/120°; C? C? O 116°/116°. The geometry of the very strong, but probably asymmetric O‥H‥O bridge is discussed (O? H 120/130, O‥O 245 pm).     

Beiträge zur Chemie des Phosphors. 152. Funktionalisierte Cyclotriphosphane des Typs (t-BuP)2PX (X = K,SiMe3, SnMe3, Cl,Br, PCl2, P(t-Bu)Cl,P(t-Bu)I)

Contributions to the Chemistry of Phosphorus. 152. Functionalized Cyclotriphosphanes of the Type (t-BuP)₂PX (X = K, SiMe₃, SnMe₃, Cl, Br, PCl₂, P(t-Bu)Cl, P(t-Bu)I) Functionalized cyclotriphosphanes of the type (t-BuP)₂PX with electropositive or electronegative substituents X have been prepared on various synthetic routes: KP(t-BuP)₂ ( 1 ) can be obtained in 50–55 per cent purity by reacting (t-BuP)₄ or (t-BuP)₃ with potassium. Reaction of 1 with Me₃SiCl or Me₃SnCl leads to the cyclotriphosphanes (t-BuP)₂PSiMe₃ ( 2 ) and (t-BuP)₂PSnMe₃ ( 3 ), respectively; the cyclocondensation of Cl(t-Bu)P? P(t-Bu)Cl with P(SnMe₃)₃, however, is more convenient for the preparation of 3 . In a similar way the halogenated compounds (t-BuP)₂PCl ( 4 ) and (t-BuP)₂PBr ( 5 ) can be obtained from Me₃Sn(t-Bu)P? P(t-Bu)SnMe₃ ( 6 ) and PX₃ (X = Cl, Br). The phosphino-substituted cyclotriphosphanes (t-BuP)₂P? PCl₂ ( 7 ), (t-BuP)₂P? P(t-Bu)Cl ( 8 ), and (t-BuP)₂P? P(t-Bu)I ( 9 ) are accessible by the reaction of 3 with PCl₃ and t-BuPX₂ (X = Cl, I), respectively. 2–9 could be obtained free from phosphorus-containing by-products and were ³¹P-NMR spectroscopically characterized as compounds with a cyclic P₃ skeleton.