Synthesis, Structure, and Chemistry of Niobium Cationic Ketenimine Complexes, [Nb(.eta.5-C5H4SiMe3)2(.eta.2-PhRCCNPh-C,N)(L)]+. Molecular Structure of [Nb(.eta.5-C5H4SiMe3)2(.eta.2-Ph2CCNPh-C,N)(CH3CN)][PF6]

• Published in: Organometallics Vol. 13; no. 4; pp. 1200 - 1207
• Main Authors: Antinolo, Antonio, Fajardo, Mariano, Gil-Sanz, Raquel, Lopez-Mardomingo, Carmen, Otero, Antonio, Atmani, Aziz, Kubicki, Marek M, El Krami, Soumia, Mugnier, Yves, Mourad, Youssef
• Format: Journal Article
• Language: English
• Published: WASHINGTON American Chemical Society 01.04.1994; Amer Chemical Soc
• Subjects: Chemistry; Chemistry, Inorganic & Nuclear; Chemistry, Organic; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; Organic chemistry; Organic compounds; Organometalloidal and organometallic compounds; Physical Sciences; Physics; Preparations and properties; Science & Technology; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Transition metals derivatives; ALKYL; INSERTION REACTIONS; ZIRCONIUM-MEDIATED FUNCTIONALIZATION; X-RAY STRUCTURE; ALKENYL; LIGAND; ZIEGLER-NATTA POLYMERIZATION; TITANIUM; ETHYLENE POLYMERIZATION; CATALYSTS; Cationic complex; Water; Catalytic reaction; Nitrile; Molecular structure; Silicon Organic compounds; Iminoacyl complexe; Organic ligand; Organic silane; Transition metal Complexes; Experimental study; X ray diffraction; Metallocene; Niobium Organic compounds; Cyclic voltammetry; Alkoxy complex; Hydroxo complex; Oxidation; Electrochemical reaction; Isocyanide; Methanol; Crystalline structure
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/om00016a024

Reaction of NbCp'2(eta2-PhRCCNPh-CN) (2a, R = Ph; 2b, R = Me; 2c, R = Et) (Cp' = eta5-C5H4SiMe3) with 1 equiv of [Cp2Fe]+X- (X = PF6, BPh4) in the presence of nitriles or isonitriles produces the cationic ketenimine niobiocene complexes [NbCP'2(eta2-PhRCCNPh-CN)(L)][X] (3a R = Ph, L = CH3CN,X=PF6; 3a'R = Ph, L = CH3CN, X = BPh4-; 3b R = Me, L = CH3CN, X = BPh4-; 3c R = Et, L = CH3CN, X = BPh4-; 3d R = Ph, L = tBuCN, X = BPh4-; 3e R = Ph, L = PhCN, X = BPh4-; 3f R = Ph, L = tBuNC, X = BPh4-; 3g R = Me, L = tBuNC, X = BPh4-; 3h R = Et, L = tBuNC, X = BPh4-) in practically quantitative yields. We have also studied the electrochemical oxidation process of 2a by means of cyclic voltammetry experiments. The structures of these compounds have been determined by spectroscopic methods. The structure of 3a was determined by single-crystal diffractometry. Compound 3a crystallizes in the triclinic space group P1BAR (No. 2) with a = 9.468(3) angstrom, b = 10-641(2) angstrom, c = 19.852(2) angstrom, alpha = 86.30(1)degrees, beta = 88.79(1)degrees, gamma = 74.64(2)degrees, Z = 2, V = 1924.6 angstrom3, D(calcd) = 1.420 g/mL, and R = 0.069, based on 5647 reflections. The molecular structure shows a typical bent-sandwich geometry around the niobium atom with the ketenimine and CH3CN ligands arrayed in the plane between the two cyclopentadienyl rings. Cationic ketenimine complexes 3 isolated as nitrile adducts are readily converted to the corresponding isonitrile compounds by treatment with an excess of isonitrile. However, the inverse reaction does not occur under the same conditions. Complexes 3a'-c react with water from wet acetone to produce the hydroxo iminoacyl complexes [NbCp'2(OH)(eta2-PhRHCCNPh-C,N)][BPh4] (5a, R = Ph; 5b, R = Me; 5c, R = Et), and 3a' reacts with methanol in the same manner to yield the corresponding methoxide complex [NbCp'2(OCH3)(eta2-Ph2HCCNPh-C,N)][BPh4], 6.