Synthese und Eigenschaften teilsilylierter Tri- und Tetraphosphane. Reaktionen lithiierter Diphosphane mit Chlorphosphanen

Synthesis and Properties of Partially Silylated Tri- and Tetraphosphanes. Reaction of Lithiated Diphosphanes with Chlorophosphanes The reactions of Li(Me₃Si)P? P(SiMe₃)(CMe₃) 1 , Li(Me₃Si)P? P(CMe₃)₂ 2 , and Li(Me₃C)P? P(SiMe₃)(CMe₃) 3 with the chlorophosphanes P(SiMe₃)(CMe₃)Cl, P(CMe₃)₂Cl, or P(CMe₃)Cl₂ generate the triphosphanes [(Me₃C)(Me₃Si)P]₂P(SiMe₃) 4 , (Me₃C)(Me₃Si)P? P(SiMe₃)? P(CMe₃)₂ 6 , [(Me₃C)₂P]₂P(SiMe₃) 7 , and (Me₃C)(Me₃Si)P? P(SiMe₃)? P(CMe₃)Cl 8 . The triphosphane (Me₃C)₂P? P(SiMe₃)? P(SiMe₃)₂ 5 is not obtainable as easily. The access to 5 starts by reacting PCl₃ with P(SiMe₃)(CMe₃)₂, forming (Me₃C)₂ P? PCl₂, which then with LiP(SiMe₃)₂ gives (Me₃C)₂ P? P(Cl)? P(SiMe₃)₂ 11 . Treating 11 with LiCMe₃ generates (Me₃C)₂P? P(H)? P(SiMe₃)₂ 16 , which can be lithiated by LiBu to give (Me₃C)₂P? P(Li)? P(SiMe₃)₂ 13 and after reacting with Me₃SiCl, finally yields 5 . 8 is stable at ?70°C and undergoes cyclization to P₃(SiMe₃)(CMe₃)₂ in the course of warming to ambient temperature, while Me₃SiCl is split off. 7 , reacting with MeOH, forms [(Me₃C)₂P]₂PH. (Me₃C)₂P? P(Li)? P(SiMe₃)₂ 18 , which can be obtained by the reaction of 5 with LiBu, decomposes forming (Me₃C)₂P? P(Li)(SiMe₃), P(SiMe₃)₃, and LiP(SiMe₃)₂, in contrast to either (Me₃C)₂P? P(Li)? P(SiMe₃)(CMe₃) 19 or [(Me₃C)₂P]₂PLi, which are stable in ether solutions. The Li phosphides 1 , 2 , and 3 with BrH₂C? CH₂Br form the n-tetraphosphanes (Me₃C)(Me₃Si)P? [P(SiMe₃)]₂? P(SiMe₃)(CMe₃) 23 , (Me₃C)₂P? [P(SiMe₃)]₂? P(CMe₃)₂ 24 , and (Me₃C)(Me₃Si)P? [P(CMe₃)]₂? P(SiMe₃)(CMe₃) 25 , respectively. Li(Me₃Si)P? P(SiMe₃)₂, likewise, generates (Me₃Si)₂P? [P(SiMe₃)]₂? P(SiMe₃)₂ 26 . Just as the n-triphosphanes 4 , 5 , 6 , and 7 , the n-tetraphosphanes 23 , 24 , and 25 can be isolated as crystalline compounds. 23 , treated with LiBu, does nor form any stable n-tetraphosphides, whereas 24 yields (Me₃C)₂P? P(Li)? P(SiMe₃)? P(CMe₃)₂, that is stable in ethers. With MeOH, 24 , forms crystals of (Me₃C)₂P? P(H)? P(SiMe₃)? P(CMe₃)₂.     

Bildung und Reaktionen silylierter Diphosphane

Preparation and Reactions of Silylated Diphosphanes The preparation of previously not available silylated diphosphanes is reported, i. e. the compounds (Me₃Si)₂P? P(SiMe₃)(CMe₃) 1 , (Me₃Si)₂P? P(CMe₃)₂ 2 and (CMe₃)₂P? P(SiMe₃)(CMe₃) 4 as well as of the respective PH containing derivatives and Li phosphides thereof. The reaction of 1 with MeOH leads to (Me₃Si)₂P? P(CMe₃) H 6 , while 4 generates (Me₃C)₂P? P(CMe₃) H 7 , and finally 3 gives access to (Me₃C)(Me₃Si)P? P(CMe₃) H 8 . LiBu on the other hand forms the Li phosphides Li(Me₃Si)P? P(SiMe₃)(CMe₃) 10 (through 1 ), Li(Me₃Si)P? P(CMe₃)₂ 11 (through 2 ), Li(Me₃C)P? P(SiMe₃)(CMe₃) 12 (through 3 ), and Li(Me₃C)P? P(CMe₃)₂ 13 (through 4 ), the latter being more easily accessible through the reaction of H(Me₃C)P? P(CMe₃)₂ with LiBu. The introduction of one single CMe₃ substituent into 1 is sufficient to obtain the Li phosphide 10 , which is stable in ethers, as opposed to the corresponding Li Phosphide of the persilylated diphosphane.     

Untersuchungen zur Bildung silylierter iso-Tetraphosphane aus P2-chlorierten Triphosphanen und Li-Phosphiden

Investigations on the Formation of Silylated iso-Tetraphosphanes We investigated the formation of iso-tetraphosphanes by reacting [Me(Me₃Si)P]₂PCl 4 , Me(Me₃Si)P? P(Cl)? P(SiMe₃)₂ 8 , Me(Me₃Si)P? P(Cl)? P(SiMe₃)(CMe₃) 9 , [Me(Me₃Si)P]₂PCl 20 , Me₃C(Me₃Si)P? P(Cl)? P(SiMe₃)₂ 21 , and [MeC(Me₃Si)P]₂PCl 22 with LiP(SiMe₃)Me 1 , LiP(SiMe₃)₂ 2 , and LiP(SiMe₃)CMe₃ 3 , respectively, to elucidate possible paths of synthesis, the influence of substituents (Me, SiMe₃, CMe₃) on the course of the reaction, and the properties of the iso-tetraphosphanes. These products are formed via a substitution reaction at the P²Cl group of the iso-triphosphanes. However, with an increasing number of SiMe₃ groups in the triphosphane as well as in reactions with LiP(SiMe₃)Me, cleaving and transmetallation reactions become more and more important. The phosphides 1,2, and 3 attack the PC1 group of 4 yielding the iso-tetraphosphanes P[P(SiMe₃)Me]₃ 5, [Me(Me₃Si)P]₂P? P(SiMe₃)₂ 6 and [Me(Me₃Si)P]₂P? P(SiMe₃)CMe₃ 7. I n reactions With 8 and 9, LiP(SiMe₃)Me causes bond cleavage and mainly leads to Me(Me₃Si)P? P(Me)? P(SiMe₃)₂ 13 and Me(Me₃Si)P? (Me)? P(SiMe₃)CMe₃ 16, resp., and to monophosphanes; minor products are [Me(SiMe₃)P]₂P? P(SiMe₃)₂ 6 and [Me(Me₂Si)P]₂P? P(SiMe₃)CMe₂ 7. LiP(SiMe₃)₂ 2 and LiP(SiMe₃)CMe₂ 3 with 8 and 9 give Me(Me₃,Si)P? P[P(SiMe₃)₂]₂ 10, Me(Me₂Si)P? P[P(SiMe₃)CMe₂]? P(SiMe₃)₂ 11, and Me(Me₃Si)P? P[P(SiMe₃)CMe₃]₂ 12 as favoured products. With 20, LiP(SiMe₃)₂ 2 forms P[P(SiMe₃)₂]₃ 28. Bond cleavage products are obtained in reactions of 20 with 1 and 2, of 21 with 1, 2, and 3, and of 22 with 1 and 2. P[P(SiMe₃)CMe₃]₃ 23 is the main product in the reaction of 22 with LiP(SiMe₃)CRle₂ 3. In the reactions of 22 with 1, 2, and 3 the cyclophosphanes P₃(CMe₃)₂(SiMe₃)25, P₄[P(SiMe₃)CMe₃]₂(CMe₃)₂ 26, and P₅(CMe₃)₄(SiMe₃) 27 are produced. The formation of these rom- pounds begins with bond cleavage in a P- SiMe, group by means of the phosphides. The thermal stability of the iso-tetraphosphanes decreases with an increasing number of silyl groups in the molecule. At 20O°C compounds 5, 7, and 23 are crystals; also 6 is stable; however, 10, It, 12, and 28 decompose already.     

Cobalt(II)-organische Phosphaniminato-Komplexe mit Heterocuban-Struktur. Kristallstrukturen von [CoBr(NPR3)]4 mit R = Me,Et, [Co(C≡C–CMe3)(NPMe3)]4 und [Co(C≡C–SiMe3)(NPEt3)]4

Organo-Cobalt(II) Phosphorane Iminato Complexes with Heterocubane Structures. Crystal Structures of [CoBr(NPR₃)]₄ with R = Me, Et, [Co(C≡C–CMe₃)(NPMe₃)]₄, and [Co(C≡C–SiMe₃)(NPEt₃)]₄ The phosphorane iminato complexes [CoBr(NPR₃)]₄, which are accessible by reaction of CoBr₂ with the silylated phosphorane imines Me₃SiNPR₃ (R = Me, Et) in the melt at 180 °C and in the presence of KF, can be transformed into the alkynyl complexes [Co(C≡C–CMe₃) · (NPMe₃)]₄ and [Co(C≡C–SiMe₃)(NPEt₃)]₄ on obtaining the heterocubane structures, when caused to react with the lithium organic reagents LiC≡C–CMe₃ and LiC≡C–SiMe₃ in THF at 0 °C. According to the crystal structure analyses all four of the compounds form heterocubane structures with only slightly distorted Co₄N₄ cubic structures.     

Zur Bildung der Cyclotetraphosphane cis- und trans-P4(SiMe3)2(CMe3)2 bei der Umsetzung von (Me3C)PCl2 mit LiP(SiMe3)2 · 2 THF

Formation of the Cyclotetraphosphanes cis- und trans-P₄(SiMe₃)₂(CMe₃)₂ in the Reaction of (Me₃C)PCl₂ with LiP(SiMe₃)₂ · 2 THF The mechanism of the reaction of (Me₃C)PCl₂ 1 with LiP(SiMe₃)₂ · 2 THF 2 was investigated. With a mole ration of 1:1 at ?60°C quantitatively (Me₃C)(Cl)P? P(SiMe₃)₂ 3 is formed. This compound eliminates Me₃SiCl on warming to 20°C, yielding Me₃Si? P?P? CMe₃ 4 (can be trapped using 2,3-dimethyl-1,3-butadiene in a 4+2 cycloaddition), which dimerizes to produce the cyclotetraphosphanes cis-P₄(SiMe₃)₂(CMe₃)₂ 5 and trans-P₄(SiMe₃)₂(CMe₃)₂ 6 . Also with a mole ratio of 1:2 initially 3 is formed which remarkably slower reacts on to give [(Me₃Si)₂P]P₂P? CMe₃ 8 . Remaining LiP(SiMe₃)₂ cleaves one Si? P bond of 8 producing (Me₃)₂P? P(CMe₃)? P(SiMe₃)₂Li. Via a condensation to the pentaphosphide 10 and an elimination of LiP(SiMe₃)₂ from this intermediate, eventually trans-P₄(SiMe₃)₂(CMe₃)₂ 6 is obtained as the exclusive cyclotetra-phosphane product.     

Bildung und struktur der Cyclophosphane P4(CMe3)2[P(CMe3)2]2 und P4(SiMe3)2[P(CMe3)2]2

Formation and Structure of the Cyclophosphanes P₄(CMe₃)₂[P(CMe₃)₂]₂ and P₄(SiMe₃)₂[P(CMe₃)₂]₂ n-Triphosphanes showing a SiMe₃ and a Cl substituent at the atoms P¹ and P², like (Me₃C)₂P? P(SiMe₃)? P(CMe₃)Cl 3 or (Me₃C)₂P? P(Cl)? P(SiMe₃)₂ 4 are stable only at temperatures below ?30°C. Above this temperature these compounds lose Me₃SiCl, thus forming cyclotetraphosphanes, P₄(CMe₃)₂[P(CMe₃)₂]₂ 1 out of 3 , P₄(SiMe₃)₂[P(SiMe₃)₂]₂ 2a (cis) and 2b (trans) out of 4 . The formation of 1 proceeds via (Me₃C)₂P? P?PCMe₃ 5 as intermediate compound, which after addition to cyclopentadiene to give the Diels-Alder-adduct 6 (exo and endo isomers) was isolated. 6 generates 5 , which then forms the dimer compound 1 . Likewise (Me₃C)₂P? P?P-SiMe₃ 8 (as proven by the adduct 7 ) is formed out of 4 , leading to 2a (cis) and 2b (trans). Compound 1 is also formed out of the iso-tetraphosphane P[P(CMe₃)₂]₂[P(CMe₃)Cl] 9 , which loses P(CMe₃)₂Cl when warmed to a temperature of 20°C. 1 crystallizes monoclinically in the space group P2₁/a (no. 14); a = 1762.0(15) pm; b = 1687.2(18) pm; c = 1170.5(9) pm; β = 109.18(5)° and Z = 4 formula units in the elementary cell. The molecule possesses E conformation. The central four-membered ring is puckered (approx. symmetry 4 2m; dihedral angle 47.4°), thus bringing the substituents into a quasi equatorial position and the nonbonding electron pairs into a quasi axial position. The bond lengths in the four-membered ring of 1 (d (P? P) = 222.9 pm) are only slightly longer than the exocyclic bonds (221.8 pm). The endocyclic bond angles \documentclass{article}\pagestyle{empty}\begin{document}$ \bar \beta $\end{document}(P/P/P) are 85.0°, the torsion angles are ±33° and d (P? C) = 189.7 pm.     

Kristallstruktur des Bis[lithium-tris(trimethylsilyl)-hydrazids] und Reaktionen mit Fluorboranen, -silanen und -phosphanen

Crystal Structure of Bis[lithium-tris(trimethylsilyl)hydrazide] and Reactions with Fluoroboranes, -silanes, and -phospanes Tris(trimethylsilyl)hydrazine reacts with n-butyllithium in n-hexane to give the lithium-derivative 1 . The reaction of 1 with SiF₄, PhSiF₃, BF₃ · OEt₂, F₂BN(SiMe₃)₂ and PF₃ leads to the substitution products 2–6 . The 1,2-diaza-3-bora-5-silacyclopentane 7 is formed by heating (Me₃Si)₂N? N(SiMe₃)(BFNSiMe₃)₂ ( 5 ) at 250°C. In the reaction of (Me₃Si)₂N? N(SiMe₃)PF₂ ( 6 ) with lithiated tert.-butyl(trimethylsilyl)amine the hydrazino-iminophosphene (Me₃Si)₂N? N = P? N(SiMe₃)(CMe₃) ( 8 ) is obtained. In the molar ratio 2:1 1 reacts with SiF₄ and BF₃ · OEt₂ to give bis[tris(trimethylsilyl)hydrazino]silane 9 and -borane 10 .     

Reducing Ga?H and Ga?C Bonds in Close Proximity to Oxidizing Peroxo Groups: Conflicting Properties in Single Molecules

Treatment of [Li(H₂Ga{CH(SiMe₃)₂}₂)] ? 2 OEt₂ ( 1? 2 OEt₂) with two equivalents of tert‐butyl hydrogen peroxide, H‐O‐O‐CMe₃, afforded the organogallium peroxide [({(Me₃Si)₂HC}₂Ga(OH)(OOCMe₃)Li)₂] ( 3 ), which possesses oxidizing peroxo groups in close proximity to reducing Ga? C bonds. The lithium atoms of the dimeric formula units are coordinated by both oxygen atoms of the peroxides and by two hydroxo groups. The cleavage of the Ga? C bond was not observed, even when an excess of H‐O‐O‐CMe₃ was applied. Instead, the adduct [{(Me₃Si)₂HC}₂Ga(OH)(OOCMe₃)₂Li₂(HOOCMe₃)] ( 4 ) was isolated, which has an intact H‐O‐O‐CMe₃ molecule terminally attached to lithium. A similar structural motif was found for the compound [(LiOOCMe₃)₂(HOOCMe₃)₂] ( 5 ). The trihydrido gallanate [Li(H₃Ga? {CH(SiMe₃)₂})] ? OEt₂ ( 2 ) yielded the unique peroxide [({(Me₃Si)₂HC}? Ga(H)(OOCMe₃)₂Li)₂] ( 6 ) under similar conditions that possesses Ga? C and even more reactive Ga? H bonds beside peroxo groups. It decomposed at room temperature by the insertion of oxygen atoms into the Ga? H bonds and the formation of [({(Me₃Si)₂HC}? Ga(OH)(OCMe₃)(OOCMe₃)Li)₂] ( 7 ), which was isolated in a low yield. Further decomposition gave the complete degradation of all peroxo groups with the formation of a relatively complicated Li₄Ga₄O₈ cage ( 8 ).     

Über die Umsetzung von Thiazylfluorid mit mehrfunktionellen Stickstoffderivaten

Reaction of Thiazylfluoride with Multifunctional Nitrogen Derivatives From the reaction of NSF 1 with LiN(SiMe₃)R′ (R′ = CMe₃, SiMe₃), linear [e. g. (Me₃C? N?S?N? )₂S ( 11 ), Me₃C? N?S?N? CMe₃ ( 14 ), Me₃Si? N?S?N? SiMe₃ ( 17 ), (Me₃Si)₂N? S? N?S?N? SiMe₃ ( 19 )] and cyclic thiazenes (S₄N₅F ( 22 )) are isolated, (S₃N₄)_n ( 23 ) is obtained in high yield from 1 and 17 (in the ratio 2:1). Possible structures for 23 are discussed; the reaction of 23 with AsF₅ gives S₄N₄ · AsF₅ ( 24 ) in a hitherto unknown modification. Possible reactions of the terminal SN groups are discussed and the structures of 11 and 24 are reported.     

Ein Beitrag zur Reaktivität von (η5-C5Me5)(CO)2FeP(SiMe3)2 gegenüber P-Chlormethylenphosphanen

On the Reactivity of (η⁵-C₅Me₅)(CO)₂FeP(SiMe₃)₂ Toward P-Chloromethylene phosphanes The reaction of (η⁵-C₅Me₅)(CO)₂FeP(SiMe₃)₂ ( 2 ) with three equivalents of Cl? P?C(SiMe₃)₂ ( 3a ) afforded the 3-methanediyl-1,3,5,6-tetraphosphabicyclo[3.1.0]hex-2-ene (η⁵-C₅Me₅)(CO)₂Fe? ( 6a ). In contrast, 2 reacts with two equivalents of Cl? P?C(Ph)SiMe₃ ( 3b ) to give the thermolabile (η⁵-C₅Me₅) · (CO)₂Fe? P[P?C(Ph)SiMe₃]₂ ( 4b ) which decomposed during the reaction with further 3b. 4 b was also obtained from (η⁵-C₅Me₅)(CO)₂Fe? P(SiMe₃)? P?C(SiMe₃)₂ ( 1a ) and two equivalents of 3b .     

Das 1,2-Bis(trimethylsilyl)3,4-di(tert-butyl)cyclotetraphosphan

1,2-Bis(trimethylsilyl)-3,4-di(tert-butyl) cyclotetraphosphane cis-P₄(SiMe₃)₂(CMe₃)₂ 1 could be prepared by the reaction of (Me₃Si)₂P—P(SiMe₃)—P(SiMe₃)CMe₃ 2 with (Me₃C)PCl₂ 3 The compound 1 forms pale yellow crystals, m. p. 116°C. The ³¹P- and ¹H-NMR data of 1 are given.     

Silyl‐Phosphino‐Carbene Complexes of Uranium(IV)

Unprecedented silyl‐phosphino‐carbene complexes of uranium(IV) are presented, where before all covalent actinide–carbon double bonds were stabilised by phosphorus(V) substituents or restricted to matrix isolation experiments. Conversion of [U(BIPM^TMS)(Cl)(μ‐Cl)₂Li(THF)₂] ( 1 , BIPM^TMS=C(PPh₂NSiMe₃)₂) into [U(BIPM^TMS)(Cl){CH(Ph)(SiMe₃)}] ( 2 ), and addition of [Li{CH(SiMe₃)(PPh₂)}(THF)]/Me₂NCH₂CH₂NMe₂ (TMEDA) gave [U{C(SiMe₃)(PPh₂)}(BIPM^TMS)(μ‐Cl)Li(TMEDA)(μ‐TMEDA)_0.5]₂ ( 3 ) by α‐hydrogen abstraction. Addition of 2,2,2‐cryptand or two equivalents of 4‐N,N‐dimethylaminopyridine (DMAP) to 3 gave [U{C(SiMe₃)(PPh₂)}(BIPM^TMS)(Cl)][Li(2,2,2‐cryptand)] ( 4 ) or [U{C(SiMe₃)(PPh₂)}(BIPM^TMS)(DMAP)₂] ( 5 ). The characterisation data for 3 – 5 suggest that whilst there is evidence for 3‐centre P?C?U π‐bonding character, the U=C double bond component is dominant in each case. These U=C bonds are the closest to a true uranium alkylidene yet outside of matrix isolation experiments.     

Die Reaktion des [(Me3Si)2CH]2Al?CH2?Al [CH(SiMe3)2]2 mit Neopentyllithium: Bildung des {[(Me3Si)2CH]2Al?CH2?Al [CH(SiMe3)2]2CH2CMe3}⊖ [Li(TMEDA)2]⊕

Reaction of [(Me₃Si)₂CH]₂Al? CH₂? Al [CH(SiMe₃)₂]₂ with Neopentyllithium: Formation of {[(Me₃Si)₂CH]₂Al? CH₂? Al [CH(SiMe₃)₂]₂CH₂CMe₃} ? [Li(TMEDA)₂]⊕ The recently synthesized methylene bridged dialuminium compound [(Me₃Si)₂CH]₂Al? CH₂? Al [CH(SiMe₃)₂]₂ reacts with neopentyl lithium in the presence of TMEDA to give the stable {[(Me₃Si)₂CH]₂Al? CH₂? Al [CH(SiMe₃)₂]₂CH₂ · CMe₃}? [Li(TMEDA)₂]⊕ decomposing at 115°C. The aluminium atoms therein are not additionally bridged, but the new substituent is occupying a terminal position as detected by crystal structure determination. A compound is formed containing a saturated, fourfold coordinated neighbouring a formally unsaturated, threefold coordinated aluminium atom. Due to high sterical restrictions the Al? C bonds are lengthened up to 209.0(3) pm at the alanate site and the Al? C? Al angle in the methylene bridge is extraordinarily enlarged to 144.4(2)°.     

Bildung siliciumorganischer Verbindungen. 108. Thermisch induzierte Reaktionen aminosubstituierter Disilane

Formation of Organosilicon Compounds. 108 [1]. Thermally Induced Reactions of Amino-Substituted Disilanes Thermally induced reactions of amino-substituted disilanes yield Si rich silanes. At 300°C, Me₃Si? SiMe₂? NMeH 1 yields Me₃Si? NMeH 2 and Me₃Si? (SiMe₂)₂-NMeH 3 in a ratio 1 : 2 : 3 = 1,6 : 1 : 1, whereas Me₃Si? SiMe₂? N(iPr)H 4 at 350°C yields Me₃Si? N(iPr)H 5 , Me₃Si? (SiMe₂)₂-N(iPr)H 6 and Me₃Si? (SiMe₂)₃? N(iPr)H 7 in a ratio of 4 : 6 : 7 = 0.8 : 1.0 : 0.6. Me₃Si? SiMe₂? NMe₂ 8 at 300°C (72 h) yields Me₃Si? NMe₂ 9 and Me₃Si-(SiMe₂)₂-NMe₂ 10 in a ratio of 9 : 8 : 10 = 1 : 0.22 : 0.44 The thermal stability of these disilanes is determined by the sterical requirements of the amino substituents NMeH < NMe₂ < N(iPr)H. The introduction of a second NMe₂ group decreases the stability and favours the formation of Si rich silanes. Such, Me₂N? (SiMe₂)₂? NMe₂ 11 already at 250°C (2 h) yields Me₂N? SiMe₂? NMe₂ 12 , Me₂N? (SiMe₂)₂? NMe₂ 13 and Me₂N? (SiMe₂)₄? NMe₂ 14 in a ratio of 11 : 13 : 14 = 0.3 : 0.9 : 1.0. The reactions can be understood as insertions of thermally produced dimethylsilylene into the Si? N bond of the disilanes. This process is strongly favoured as compared to the trapping reactions with Ph? C?C? Ph or Et₃SiH. The mentioned reactions correspond closely to those of the methoxy-disilanes[2]. However (MeN? SiMe₂? SiMe₂)₂ 15 , obtained from HMeN? (SiMe₂)₂? NMeH by condensation [3], at 400°C suffers a ring contraction to octymethyl-1,3-diaza-2,4,5-trisilacyclopentane (69 weight %), and yields also some solid residue, the composition of which corresponds to Si₃C₇NH₂₁.     

Reaktionen silylierter Cyclotetraphosphane mit Lithiumalkylen

Reactions of Silylated Cyclotetraphosphanes with Lithium Alkyles While the cyclotetraphosphanes P₄(CMe₃)₃SiMe₃ 1 and trans-P₄(CMe₃)₂(SiMe₃)₂ 2 in reaction with LiR (R = Me, n-Bu) in THF yield the cyclic phosphides LiP₄(CMe₃)₃ 3 and trans-LiP₄(CMe₃)₂SiMe₃ 4 , respectively, the compounds P₄(SiMe₃)₄ 5 , P₄(SiMe₃)₃ CMe₃ 6 and cis-P₄(CMe₃)₂(SiMe₃)₂ 7 by cleavage of a P? P bond produce primary n-tetraphosphides, which rearrange (1,3-shift of Li/SiMe₃) in THF even at low temperature to form the corresponding secondary n-tetraphosphides. Warming these solutions to room temperature initiates consecutive reactions including elimination of LiP(SiMe₃)₂, (Me₃Si)₃P, RP(SiMe₃)₂ and producing P-rich compounds. In this way Li₃P₇ is obtained as main-product from compound 5 , and LiP₅(CMe₃)₄, LiP₃(CMe₃)₂, P₄(CMe₃)₄ from compound 7 . However, the reaction of 6 and LiR gives raise only to traces of Li₃P₇ and Li₂P₇CMe₃. The above mentioned primary as well as the secondary n-tetraphosphides generate stable n-tetraphosphane derivatives by reaction with Me₃SiCl, or MeCl, respectively.     

Übergangsmetall-substituierte Acylphosphane und Phosphaalkene. 22 [1] Insertionen von Hexafluoraceton in die PX-Bindung von Metallophosphanen des Typs (η5-C5Me5)(CO)2M?PX2 (M = Fe,Ru; X = Me3Si,Cl). Strukturbestimmung von (η5-C5Me5)(CO)2Fe?P(SiMe3)C(CF3)2(OSiMe3)

Transition Metal-substituted Acylphosphanes and Phosphaalkenes. 22. Insertions of Hexafluoroacetone into the PX-Bond of Metallophosphanes (η⁵-C₅Me₅)(CO)₂M? PX₂ (M = Fe, Ru; X = Me₃Si, Cl). Structure Determination of (η⁵-C₅Me₅)(CO)₂Fe? P(SiMe₃)C(CF₃)₂(OSiMe₃) Reaction of the metallophosphanes (η⁵-C₅Me₅)(CO)₂M? P(SiMe₃)₂ ( 1a : M = Fe; 1b : M = Ru) with hexafluoroacetone (HFA) afforded the complexes (η⁵-C₅Me₅)(CO)₂M? P(SiMe₃)C(CF₃)₂(OSiMe₃) ( 2a, b ). The attempted synthesis of a metallophosphaalkene from 2a by thermal elimination of hexamethyldisiloxane failed. The acid catalyzed hydrolysis of 2a afforded compound (η⁵-C₅Me₅) · (CO)₂Fe? P(H)C(CF₃)₂(OSiMe₃) ( 3 ). Hexafluoracetone and (η⁵-C₅Me₅)(CO)₂Fe? PCl₂ ( 4 ) under-went reaction to give the metallochlorophosphan (η⁵-C₅Me₅) · (CO)₂Fe? P(Cl)? O? C(CF₃)₂Cl ( 5 ). Constitutions and configurations of the compounds ( 2–5 ) were established by elemental analyses and spectroscopic data (IR, ¹H-, ¹³C, ¹⁹F-, ²⁹Si-, ³¹P-NMR, MS). The molecular structure of 2a was determined by x-ray diffraction analysis.     

Phosphaniminato‐Cluster von Eisen. Die Kristallstrukturen von [FeCl(NPEt3)]4, [Fe(C=C–SiMe3)(NPEt3)]4 und [Fe3Cl4{NP(NMe2)3}3]

Phosphoraneiminato Cluster of Iron. The Crystal Structures of [FeCl(NPEt₃)]₄, [Fe(C=C–SiMe₃)(NPEt₃)]₄, and [Fe₃Cl₄{NP(NMe₂)₃}₃] The reaction of iron dichloride with the silylated phosphaneimine Me₃SiNPEt₃ in the presence of potassium fluoride at 165 ?C leads to the phosphoraneiminato complex [FeCl(NPEt₃)]₄ ( 1 ). Compound 1 forms black, moisture and oxygen sensitive crystals. According to the crystal structure analysis 1 has a heterocubane structure, in which the iron and the nitrogen atoms of the NPEt₃^– groups occupy the corners of a distorted cube and form Fe–N–Fe bond angles of 83.1? and N–Fe–N angles of 96.5?. This results in significantly short Fe…Fe contacts of 272.9 pm. The results of magnetic susceptibility measurements in the range of temperatures from 1.8 to 293 K and the ⁵⁷Fe‐Mössbauer spectra in the range of temperatures from 2 to 300 K are reported. Compound 1 reacts with the lithiated acetylenes LiC=C–CMe₃ and LiC=C–SiMe₃ in n‐hexane to form the iron‐organic derivatives [Fe(C=C–R)(NPEt₃)]₄ [R = CMe₃ ( 2 a ), R = SiMe₃ ( 2 b )] keeping the heterocubane structure. Compounds 2 a and 2 b form crystals which are very reactive and also black. According to the crystal structure analysis 2 b has a Fe₄N₄ heterocubane structure which is less distorted than that in 1 with bond angles Fe–N–Fe of 85.5? and N–Fe–N of 94.2?. This leads to the longer Fe…Fe contacts of 281.4 pm. With the dimethylamido derivative Me₃SiNP(NMe₂)₃ iron dichloride reacts under conditions similar to those in the synthesis of 1 to form the dark green mixed‐valenced Fe^II/Fe^III cluster [Fe₃Cl₄{NP(NMe₂)₃}₃] ( 3 ). According to the crystal structure analysis the three iron atoms in 3 are connected via one μ₃‐N atom of a NP(NMe₂)₃^– ligand, via two μ‐N atoms of the two remaining phosphoraneiminato ligands, and via one μ‐Cl atom to form an incomplete heterocubane skeleton.     

[WCl4(Me3Si?CC?SiMe3)]2 Synthese,IR-Spektrum und Kristallstruktur

[WCl₄(Me₃Si? C?C? SiMe₃)]₂. Synthesis, I.R. Spectrum, and Crystal Structure The title compound is obtained from tungsten hexachloride and bis-trimethylsilyl acetylene in the presence of C₂Cl₄ in dichloro methane, forming green crystals. The complex is characterized by the mass spectrum, the i.r. spectrum, and by a structural analysis with the aid of X-ray diffraction data. [WCl₄(Me₃Si? C?C? SiMe₃)]₂ crystallizes triclinic in the space group P1 with one dimeric formula unit per unit cell (2 231 observed, independent reflexions, R = 4.6%). The cell dimensions are a = 928, b = 938, c = 1 080 pm; α = 115.3°, β = 91.9°, γ = 100.0°. The complex forms centrosymmetric dimers, the units being linked by chloro bridges of bond lengths W? Cl 244 and 272 pm. The trans-position to the long W? Cl bridge is occupied by the acetylene ligand which is bonded side-on with identical W? C bond lengths of 203 pm. Together with the three terminal chlorine ligands (mean W? Cl distance 231 pm) the tungsten atom achieves coordination number seven.     

Structural Analysis of Zincocenes with Substituted Cyclopentadienyl Rings

New zincocenes [ZnCp′₂] ( 2 – 5 ) with substituted cyclopentadienyl ligands C₅Me₄H, C₅Me₄tBu, C₅Me₄SiMe₂tBu and C₅Me₄SiMe₃, respectively, have been prepared by the reaction of ZnCl₂ with the appropriate Cp′‐transfer reagent. For a comparative structural study, the known [Zn(C₅H₄SiMe₃)₂] ( 1 ), has also been investigated, along with the mixed‐ring zincocenes [Zn(C₅Me₅)(C₅Me₄SiMe₃)] ( 6 ) and [Zn(C₅Me₅)(C₅H₄SiMe₃)] ( 7 ), the last two obtained by conproportionation of [Zn(C₅Me₅)₂] with 5 or 1 , as appropriate. All new compounds were characterised by NMR spectroscopy, and by X‐ray methods, with the exception of 7 , which yields a side‐product ( C ) upon attempted crystallisation. Compounds 5 and 6 were also investigated by ¹³C CPMAS NMR spectroscopy. Zincocenes 1 and 2 have infinite chain structures with bridging Cp′ ligands, while 3 and 4 exhibit slipped‐sandwich geometries. Compounds 5 and 6 have rigid, η⁵/η¹(σ) structures, in which the monohapto C₅Me₄SiMe₃ ligand is bound to zinc through the silyl‐bearing carbon atom, forming a Zn? C bond of comparable strength to the Zn? Me bond in ZnMe₂. Zincocene 5 has dynamic behaviour in solution, but a rigid η⁵/η¹(σ) structure in the solid state, as revealed by ¹³C CPMAS NMR studies, whereas for 6 the different nature of the Cp′ ligands and of the ring substituents of the η¹‐Cp′ group (Me and SiMe₃) have permitted observation for the first time of the rigid η⁵/η¹ solution structure. Iminoacyl compounds of composition [Zn(η⁵‐C₅Me₄R)(η¹‐C(NXyl)C₅Me₄R)] resulting from the reactions of some of the above zincocenes and CNXyl (Xyl=2,6‐dimethylphenylisocyanide) have also been obtained and characterised.     

Trialkylhydridoalanate RxR′3-xAlH⊖ [R = CMe3; R′ = CH(SiMe3)2]

Trialkylhydridoalanates R_xR′_3?xAlH^? [R = CMe₃; R′ = CH(SiMe₃)₂] The very strong base tert-butyl lithium reacts in the presence of chelating tetramethylethylendiamine with the aluminium organyls Al[CH(SiMe₃)₂]₂CMe₃ 1 and Al[CH(SiMe₃)₂](CMe₃)₂ 2 not under proton abstraction from the C? H acidic elementorganic substituent, but under β-elimination and addition of the thereby formed LiH to the coordinatively unsaturated aluminium atom. Two alanates — [Hal{CH(SiMe₃)₂}₂CMe₃]^? 3 and [HAl{CH(SiMe₃)₂}(CMe₃)₂]^? 4 each with Li(TMEDA)₂^⊕ as counterion — were isolated; they exhibit separate anions and cations in solid state as shown by a crystal structure determination on 3 . In absence of the chelating amine tert-butyl lithium decomposes under the catalytic effect of the aluminium compound to LiH, which does not add to aluminium and precipitates in a reactive form.