alpha-Addition von Aminen, Iminen und Hydrazinen an Allenyliden-Komplexe : Bildung von Carben-, Azetidinyliden- und Nitril-Komplexen

Diarylallenylidene(pentacarbonyl)-chromium and -tungsten complexes, (CO)5M=C=C=CR2 (M = W (1), Cr (2)), react with amines, imines and hydrazines by addition of the nitrogen nucleophile to the Cαallenylidene atom. With NEt3 the adduct formation is reversible. With secondary and primary amines, imines and hydrazines, the initially formed N-ylide complexes react readily further to give carbene, azetidinylidene and nitrile complexes, respectively. For example the reaction of (a) 1 and 2 with HNEt2 or H2NPh gives alkenyl(amino)carbene complexes, (CO)5M=C [C(H)=CR2] NR′2 (3–5); (b) of 1 and 2 with HN=CR2 gives alkenyl(alkylideneamino)carbene complexes, (CO)5M=C [C(H)=CR2] [N=CR′2] (6,7); (c) of 1 with (iPr)N=C(Ph) H the azetidinylidene complex 9; (d) of 1 with 1,2-disubstituted hydrazines such as H(Me)NN(R)H (R = Me, Ph) alkenyl (hydrazino)carbene complexes, (CO)5M=C [C(H)=CR2] [N(Me)N(R)H] (11) and (e) of 1 with H2NNR1R 2 (R1 = R2 = H, Me; R1 = H, R2 = Ph) alkenyl(amino)carbene complexes (13) and/or aciylnitrile complexes, (CO)5W[N = C-C(H=CR2] (12). The structures of representative examples of 6, 11 and 12 were established by X-ray analyses

Addition von Phosphanen an das Cα-Atom von Allenyliden(pentacarbonyl)chrom und Umlagerung in Phosphan-Komplexe

The allenylidene(pentacarbonyl)chromium complex (CO)5Cr[C=C=C(C6H4NMe2-p)2] (1a) adds phosphines PR3 at the Cα atom to give ylide complexes, (CO)5Cr-[C(PR3=C=C(C6H4NMe2-p)2] (PR3 = PMe3 (3), PHPh2 (3), PH2Mes (7) (Mes = C6H2Me3-2,4,6)). At room temperature complex 3 slowly rearranges to the allenylphosphine complex (CO)5Cr-PPh2[CH=C=C(C6H4NMe2-p)2] (4). The structure of 4 was established by an X-ray structure analysis. The adduct 7 obtained from 1a and PH2Mes, however, could not be detected. It immediately isomerizes to the alkynylphosphine complex (CO)5Cr-PH(Mes)[C≡C-CH(C6H4NMe2-p)2] (8). At room temperature the ylide complex 5, formed by addition of PHPh2 to the Cα atom of the allenylidene complex (CO)5Cr=C=C=C(o-C6H4)2O (1b), rearranges in CH2Cl2 in the presence of excess PHPh2 to give a binuclear bisphosphine complex (6). 6 corresponds to the product of the chemo-, regio- and stereo-selective dimerization of the allenylphosphine complex analogous to 4

Zirconocene dipicolinate and related dicarboxylate complexes : coordination geometries and reactivities

Monomeric zirconocene dipicolinate complexes, which have a formal 18-electron configuration, are stable towards water and relatively inert against aqueous HCl. Methylmagnesium chloride attacks these complexes at the dipicolinate carboxyl groups and subsequent reaction with aqueous HCl gives 2,6-diacetyl pyridine and the zirconocene dichloride. Other dicarboxylates, such as 3,4-dimethoxyfurane-2,5-dicarboxylate or isophthalate, form binuclear zirconocene complexes, in which one bidentate and one monodentate carboxylate ligand generate a formal 18-electron configuration. These complexes react with methylmagnesium chloride to give the respective zirconocene dimethyl complexes, i.e. by normal replacement of C=O bonds by C-CH3 bonds

Borata-Alkene Derived Syntheses of (F₅C₆)₂B‑Substituted Bis(indenyl) Group 4 Metal Complexes

An indene based borata-alkene was used as a reagent for the synthesis of B­(C₆F₅)₂-functionalized group 4 bent-metallocene complexes. The respective borata-alkene was prepared by HB­(C₆F₅)₂ hydroboration of dimethylbenzofulvene followed by deprotonation with lithium tetramethylpiperidide. Treatment of CpTiCl₃ or CpZrCl₃ with the borata-alkene gave the respective [(C₆F₅)₂B-indenyl]­CpMCl₂ bent-metallocene complexes. Both were characterized by X-ray diffraction. The boryl-functionalized metallocenes gave active ethene or propene polymerization catalysts, respectively, upon activation with triethylaluminum