Abstract:Das mit VOCl3 isoelektronische [VNCl3]⊖ entsteht mit Ph3PNPPh3⊕ als Gegenion in Form orangeroter Kristalle bei der Einwirkung von Ph3PNPPh3Cl auf Cl3VNSiMe3 in Dichlormethanlösung. Mit α,α'‐Dipyridyl entsteht hieraus braunes, über Chlorobrücken assoziiertes VNCl2(Dipy). Die IR‐Spektren werden mitgeteilt.
“…As always in cases like this, there remains the possibility of a cocrystallizing paramagnetic impurity (∼1%; S = 2) but there is also the possibility of genuine Pauli paramagnetism (temperature-independent paramagnetism). It is noted that Dehnicke et al4b have reported similar magnetic behavior for [V V NCl 2 (pyr) 2 ], for which they found 0.8 μ B /V.…”
Section: Resultsmentioning
confidence: 71%
“…This b 2 orbital is empty for V(V), half-filled in Cr(V), and filled in Mn(V) complexes. Due to an enormous structural trans-influence of the nitrido group, the ligand in a trans position is labilized to such an extent that nearly all complexes reported to date are five-coordinate, square pyramidal species with the nitrido group in the apical position (Table ). − This is thought to be the reason that, to the best of our knowledge, no octahedral nitrido complexes of vanadium(V), chromium(V), or manganese(V) have been structurally characterized. By making use of the well-known kinetic stability of the facially coordinated tridentate macrocycle 1,4,7-triazacyclononane (L) and its N-substituted derivatives, we have synthesized and characterized a series of octahedral nitrido complexes of V(V), Cr(V), and Mn(V) containing an [LM(didentate)] 2+ fragment. 1 Partial qualitative molecular orbital scheme for octahedral complexes with one terminal nitrido ligand; adapted from ref , p 33.…”
Photolysis of a series of octahedral monoazido complexes of the type [LM(III)(didentate ligand)(N(3))](n)(+)X(n) of vanadium(III), chromium(III), and manganese(III) in the solid state or in solution yields quantitatively the corresponding six-coordinate nitrido complexes [LM(V)(didentate ligand)(N)](n)(+)X(n) and 1 equiv of dinitrogen. L represents the macrocycle 1,4,7-triazacyclononane or its N-methylated derivative (L'), the didentate ligands are pentane-2,4-dionate (acac), 2,2,6,6-tetramethylheptane-3,5-dionate (tacac), picolinate (pic), phenanthroline (phen), and oxalate (ox), and X(-) represents perchlorate or hexafluorophosphate. The following nitrido complexes were prepared: [LV(V)(N)(acac)](ClO(4)) (6), [LCr(V)(N)(acac)](ClO(4)) (13), [LCr(V)(N)(tacac)](ClO(4)) (14), [LCr(V)(N)(pic)](ClO(4)) (15), [LCr(V)(N)(phen)](ClO(4))(2) (16), [LCr(V)(N)(ox)] (19), [L'Mn(V)(N)(acac)]PF(6) (21). Photolysis of [LCr(III)(N(3))(ox)] (17) in the solid state produces the &mgr;-nitrido-bridged mixed-valent species [L(2)Cr(2)(ox)(2)(&mgr;-N)](N(3)) (18). The structures of the precursor complex [L'Mn(acac)(N(3))]BPh(4) (20), of 13, and of [L'Mn(V)(N)(acac)]BPh(4) (21) have been determined by X-ray crystallography. Complex 13 crystallizes in the orthorhombic space group Pnma, with cell constants a = 27.187(5) Å, b = 9.228(2) Å, c = 7.070(1) Å, V = 1773.7(6) Å(3), and Z = 4; complex 20 crystallizes in the triclinic space group P&onemacr; with a = 14.769(5) Å, b = 16.83(1) Å, c = 16.96(1) Å, alpha = 108.19(5) degrees, beta = 105.06(4) degrees, gamma = 99.78(4) degrees, V = 3719(2) Å(3), and Z = 4; and complex 21 crystallizes in the monoclinic space group P2(1)/n with a = 10.443(3) Å, b = 16.035(4) Å, c = 21.463(5) Å, beta = 95.76(1) degrees, V = 3575.9(14) Å(3), and Z = 4. The Cr(V)&tbd1;N and Mn(V)&tbd1;N distances are short at 1.575(9) and 1.518(4) Å, respectively, and indicate a metal-to-nitrogen triple bond.
“…As always in cases like this, there remains the possibility of a cocrystallizing paramagnetic impurity (∼1%; S = 2) but there is also the possibility of genuine Pauli paramagnetism (temperature-independent paramagnetism). It is noted that Dehnicke et al4b have reported similar magnetic behavior for [V V NCl 2 (pyr) 2 ], for which they found 0.8 μ B /V.…”
Section: Resultsmentioning
confidence: 71%
“…This b 2 orbital is empty for V(V), half-filled in Cr(V), and filled in Mn(V) complexes. Due to an enormous structural trans-influence of the nitrido group, the ligand in a trans position is labilized to such an extent that nearly all complexes reported to date are five-coordinate, square pyramidal species with the nitrido group in the apical position (Table ). − This is thought to be the reason that, to the best of our knowledge, no octahedral nitrido complexes of vanadium(V), chromium(V), or manganese(V) have been structurally characterized. By making use of the well-known kinetic stability of the facially coordinated tridentate macrocycle 1,4,7-triazacyclononane (L) and its N-substituted derivatives, we have synthesized and characterized a series of octahedral nitrido complexes of V(V), Cr(V), and Mn(V) containing an [LM(didentate)] 2+ fragment. 1 Partial qualitative molecular orbital scheme for octahedral complexes with one terminal nitrido ligand; adapted from ref , p 33.…”
Photolysis of a series of octahedral monoazido complexes of the type [LM(III)(didentate ligand)(N(3))](n)(+)X(n) of vanadium(III), chromium(III), and manganese(III) in the solid state or in solution yields quantitatively the corresponding six-coordinate nitrido complexes [LM(V)(didentate ligand)(N)](n)(+)X(n) and 1 equiv of dinitrogen. L represents the macrocycle 1,4,7-triazacyclononane or its N-methylated derivative (L'), the didentate ligands are pentane-2,4-dionate (acac), 2,2,6,6-tetramethylheptane-3,5-dionate (tacac), picolinate (pic), phenanthroline (phen), and oxalate (ox), and X(-) represents perchlorate or hexafluorophosphate. The following nitrido complexes were prepared: [LV(V)(N)(acac)](ClO(4)) (6), [LCr(V)(N)(acac)](ClO(4)) (13), [LCr(V)(N)(tacac)](ClO(4)) (14), [LCr(V)(N)(pic)](ClO(4)) (15), [LCr(V)(N)(phen)](ClO(4))(2) (16), [LCr(V)(N)(ox)] (19), [L'Mn(V)(N)(acac)]PF(6) (21). Photolysis of [LCr(III)(N(3))(ox)] (17) in the solid state produces the &mgr;-nitrido-bridged mixed-valent species [L(2)Cr(2)(ox)(2)(&mgr;-N)](N(3)) (18). The structures of the precursor complex [L'Mn(acac)(N(3))]BPh(4) (20), of 13, and of [L'Mn(V)(N)(acac)]BPh(4) (21) have been determined by X-ray crystallography. Complex 13 crystallizes in the orthorhombic space group Pnma, with cell constants a = 27.187(5) Å, b = 9.228(2) Å, c = 7.070(1) Å, V = 1773.7(6) Å(3), and Z = 4; complex 20 crystallizes in the triclinic space group P&onemacr; with a = 14.769(5) Å, b = 16.83(1) Å, c = 16.96(1) Å, alpha = 108.19(5) degrees, beta = 105.06(4) degrees, gamma = 99.78(4) degrees, V = 3719(2) Å(3), and Z = 4; and complex 21 crystallizes in the monoclinic space group P2(1)/n with a = 10.443(3) Å, b = 16.035(4) Å, c = 21.463(5) Å, beta = 95.76(1) degrees, V = 3575.9(14) Å(3), and Z = 4. The Cr(V)&tbd1;N and Mn(V)&tbd1;N distances are short at 1.575(9) and 1.518(4) Å, respectively, and indicate a metal-to-nitrogen triple bond.
“…-3LiCl ( 11) Die Reaktion von 1 mit überschüssigem Chlorwas serstoff führt über die Zwischenstufe 2, die in reiner Form nur mit geringer Ausbeute (2 -3%) abgetrennt werden kann, zu einer Vanadiumverbindung 6 von unbekannter Konstitution. In der Reaktionslösung werden nur Trimethylchlorsilan ( l H-NMR) und 2 (51V-NMR) nachgewiesen.…”
Imidovanadium(V) TrichloridesThe reactions of Me3SiN=VCl3 (1) with MeOH, PhOH, HCl, PyH+Cl~ or LiO'Bu have been studied. The reductive decomposition of 1 by hydrogen chloride in toluene yields HN=VC13 as a labile intermediate which could be isolated only in a small amount. The syntheses of RN=VC13 (R = neopent, "Pr, cyclohex, CPh3, 1-Ad) and [('BuN)2V2Cl4(/i-OC13H9)2] (15) are also described. All compounds obtained are characterized by 5 V NMR spectroscopy, the fluorenolato complex 15 by X-ray diffraction analysis. Einleitung Arylimidovanadium(V)-trichloride sind bekannt und auf folgendem Weg zugänglich [1]: Ergebnisse und Diskussion Halogenid-Ionen (F-, CI" ) spalten die Silicium-Stickstoff-Bindung in 1 unter Bildung des Nitrido-Komplexes [N = VC13]" [10, 11]. Wir haben in Toluol die Reaktion von 1 mit Me thanol, Phenol und Chlorwasserstoff im Mol verhältnis 1 : 1 untersucht und gefunden, daß der nucleophile Angriff von Methanol und Phe nol am Vanadiumatom unter Eliminierung von Chlorwasserstoff erfolgt, während Chlorwasser stoff das Siliciumatom angreift und die Si-N-Bindung spaltet unter Bildung von HN=VC13 (2), siehe Gin. (7), (8), (10).Bei der äquimolaren Umsetzung von 1 mit Chlor wasserstoff entsteht in der Reaktionslösung ein unlöslicher, gelber Niederschlag. Die 51V-NMR-Reaktionskontrolle liefert die Signale von 1 und 2, was zeigt, daß bereits vor dem vollständigen Ab lauf der Reaktion (8) die Zersetzung des Imidovanadium(V)-trichlorids durch Chlorwasserstoff ein setzt (Gl. (11)).
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