Abstract:Die Tetrachloride von Zirconium und Hafnium reagieren mit überschüssigem Phosphanimin Me3SiNPMe3 bei 220°C in Gegenwart von Natriumfluorid unter Abspaltung von FSiMe3 und Bildung der komplexen Ionenverbindungen [Zr3Cl6(NPMe3)5]+[Zr2Cl6(NPMe3)3]− und [Hf3Cl6(NPMe3)5]+[Hf2Cl7(NPMe3)2]−. Nach Kristallstrukturanalysen bilden in den Kationen die drei Metallatome zusammen mit drei NPMe3−‐Gruppen mit μ2‐N‐Funktion und zwei NPMe3−‐Gruppen mit μ3‐N‐Funktion trigonale Bipyramiden. Im Anion des Zirconium‐Komplexes sind d… Show more
“…In both cases the P−N−Zr angles were approaching linearity, being 174.8(4) and 175.2(4)° in 1 and 2 , respectively. These are much larger than those reported for the related dimeric ([Zr 2 Cl 4 (NPMe 3 ) 4 ( μ -HNPMe 3 )]) (159.3(2), 155.6(2)°) and trimeric ([Zr 3 Cl 6 (NPMe 3 ) 5 ] + ) (132.9(7), 126.1(6)°) species. The P−N bond distances of 1.588(5) and 1.569(7) Å, respectively, are typical of those found in other group IV phosphinimide complexes .…”
Section: Resultsmentioning
confidence: 65%
“…The P−N bond distances of 1.588(5) and 1.569(7) Å, respectively, are typical of those found in other group IV phosphinimide complexes . The Zr−N bond distances of 1.902(5) and 1.926(7) Å in 1 and 2 , respectively, are significantly shorter than the Zr−N bond distances found in the dimeric and trimeric species (1.95(2)−2.27(9) Å). − This suggests some degree of Zr−N multiple bond character. 1 ORTEP drawing of 1 .…”
Zirconium phosphinimide complexes of the form CpZr(NP-t-Bu 3 )Cl 2 (1) and Cp*Zr(NPR 3 )-Cl 2 (R ) i-Pr (2), t-Bu (3)) were readily prepared under ambient conditions via the reaction of [CpZrCl 3 ] n or Cp*ZrCl 3 with the appropriate trialkylphosphinimide lithium salt (R 3 PNLi). A series of derivatives were readily obtained via alkylation or arylation of the above dihalide precursors. These included CpZr(NP-t-Bu 3 )Me 2 (4), Cp*Zr(NPR 3 )Me 2 (R ) i-Pr (5), t-Bu (6)),. Reaction of 17 with the borane B(C 6 F 5 ) 3 yielded the zwitterionic and cationic complexes Cp*Zr(NP-t-Bu 3 )(CH 2 C(CH 3 )C(CH 3 )CH 2 B(C 6 F 5 ) 3 ) (18) and Cp*Zr(NP-t-Bu 3 )(THF)-(CH 2 C(CH 3 )C(CH 3 )CH 2 B(C 6 F 5 ) 3 ) (19). A number of the above compounds were screened for their potential as catalyst precursors in ethylene polymerization. In general, upon activation with methylaluminoxane, the resulting catalysts exhibit low activity. Efforts to understand the deactivation pathway for these zirconium catalysts involved investigating the interactions of catalyst precursors with activators. For example, reaction of 4 with the borane B(C 6 F 5 ) 3 leads to aryl group transfer and formation of catalytically inactive CpZr(NP-t-Bu 3 )(C 6 F 5 ) 2 (20). Interactions with MAO were modeled via reaction with AlMe 3 . The Zr clusters (Cp*Zr) 4 -(µ-Cl) 5 (Cl)(µ-CH) 2 ( 21) and (Cp*Zr) 5 (µ-Cl) 6 (µ-CH) 3 ( 22) were two of the products that were characterized from these reactions. The isolation of 21 and 22 infers that aryl for methyl exchange, ligand abstraction, and C-H bond activation may be catalyst deactivation pathways.
“…In both cases the P−N−Zr angles were approaching linearity, being 174.8(4) and 175.2(4)° in 1 and 2 , respectively. These are much larger than those reported for the related dimeric ([Zr 2 Cl 4 (NPMe 3 ) 4 ( μ -HNPMe 3 )]) (159.3(2), 155.6(2)°) and trimeric ([Zr 3 Cl 6 (NPMe 3 ) 5 ] + ) (132.9(7), 126.1(6)°) species. The P−N bond distances of 1.588(5) and 1.569(7) Å, respectively, are typical of those found in other group IV phosphinimide complexes .…”
Section: Resultsmentioning
confidence: 65%
“…The P−N bond distances of 1.588(5) and 1.569(7) Å, respectively, are typical of those found in other group IV phosphinimide complexes . The Zr−N bond distances of 1.902(5) and 1.926(7) Å in 1 and 2 , respectively, are significantly shorter than the Zr−N bond distances found in the dimeric and trimeric species (1.95(2)−2.27(9) Å). − This suggests some degree of Zr−N multiple bond character. 1 ORTEP drawing of 1 .…”
Zirconium phosphinimide complexes of the form CpZr(NP-t-Bu 3 )Cl 2 (1) and Cp*Zr(NPR 3 )-Cl 2 (R ) i-Pr (2), t-Bu (3)) were readily prepared under ambient conditions via the reaction of [CpZrCl 3 ] n or Cp*ZrCl 3 with the appropriate trialkylphosphinimide lithium salt (R 3 PNLi). A series of derivatives were readily obtained via alkylation or arylation of the above dihalide precursors. These included CpZr(NP-t-Bu 3 )Me 2 (4), Cp*Zr(NPR 3 )Me 2 (R ) i-Pr (5), t-Bu (6)),. Reaction of 17 with the borane B(C 6 F 5 ) 3 yielded the zwitterionic and cationic complexes Cp*Zr(NP-t-Bu 3 )(CH 2 C(CH 3 )C(CH 3 )CH 2 B(C 6 F 5 ) 3 ) (18) and Cp*Zr(NP-t-Bu 3 )(THF)-(CH 2 C(CH 3 )C(CH 3 )CH 2 B(C 6 F 5 ) 3 ) (19). A number of the above compounds were screened for their potential as catalyst precursors in ethylene polymerization. In general, upon activation with methylaluminoxane, the resulting catalysts exhibit low activity. Efforts to understand the deactivation pathway for these zirconium catalysts involved investigating the interactions of catalyst precursors with activators. For example, reaction of 4 with the borane B(C 6 F 5 ) 3 leads to aryl group transfer and formation of catalytically inactive CpZr(NP-t-Bu 3 )(C 6 F 5 ) 2 (20). Interactions with MAO were modeled via reaction with AlMe 3 . The Zr clusters (Cp*Zr) 4 -(µ-Cl) 5 (Cl)(µ-CH) 2 ( 21) and (Cp*Zr) 5 (µ-Cl) 6 (µ-CH) 3 ( 22) were two of the products that were characterized from these reactions. The isolation of 21 and 22 infers that aryl for methyl exchange, ligand abstraction, and C-H bond activation may be catalyst deactivation pathways.
“…IR spectra were recorded as Nujol mulls on a Bruker IFS-88 FT, using CsI and polyethylene plates. Assignment of IR bands was made on the basis of comparative literature data. − ,, Mass spectra were recorded on either Varian MAT CH 7 or Varian MAT 711 by electron impact at 70 eV.…”
Section: Methodsmentioning
confidence: 99%
“…On the other hand, in (NPR 3 - ) complexes of electron-poor 4d-metals in their highest oxidation states {e.g. Zr(IV), Nb(V), Mo(VI) 5 } both terminal (A) and μ 2 -bridging (B) modes of the ligand have recently been described.…”
Phosphoraniminato complexes of cadmium [CdX(NPEt 3 )] 4 {X ) Cl (1), Br (2), I (3), [CdI(NPMe 3 )] 4 (4)} are formed by the reaction of cadmium dihalides with silylated phosphoranimines Me 3 SiNPR 3 (R ) Me, Et) in the presence of a fluoride source, e.g. NaF, at elevated temperatures. High yields can be achieved when R ) Et and X is a heavy halogen. The exocyclic bromo function in complex 2 can be replaced by reaction with organolithium reagents to give organocadmium compounds [CdMe(NPEt 3 )] 4 (5) and [Cd(C 2 SiMe 3 )(NPEt 3 )] 4 (6) in excellent yields. Complexes 1-6 consist of a [Cd 4 N 4 ] heterocubane core in which the cadmium atoms are linked by µ 3 -N bridges of the phosphoraniminato ligand with the cubane angles being close to 90°. The crystal structure of an unsymmetrical cubane [Cd 4 I 4 (OSiMe 3 )(NPEt 3 ) 3 ] (7) is reported, in which one of the phosphoraniminato moieties has been replaced by a silyloxy function. All complexes are colorless oxygen-and moisture-sensitive crystalline materials, the heterocubane structure of which has been shown by crystal structure determinations and is consistent with spectroscopic findings, including IR, NMR, and mass spectra.
[Zr2Cl4(NPMe3)4(HNPMe3)] · CH3CN, a Phosphorane Iminato Complex with ZrN Double Bonds
The title compound has been prepared from a molten mixture of ZrCl4 with Me3SiNPMe3 in the presence of potassium fluoride and subsequent extraction with acetonitrile. According to the crystal structure determination the zirconium atoms are linked by three μ2‐N atoms of two NPMe3− groups and by the HNPMe3 molecule. Two terminal bounded chlorine atoms and a terminally coordinated NPMe3− ligand complete the distorted octahedral surrounding of the zirconium atoms thus forming an edge sharing double octahedron. The ZrN bond lengths of the terminal NPMe3− groups of 194.6 pm correspond with double bonds.
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