Koordinationschemie mit den komplexen Chelatliganden [{Fe₂Cp₂(CO)₃}₂{CN[CH₂]_nNC}] (n = 2, 3). Heteropentanukleare „Superkomplexe”︁ mit μ₅Diisocyanid‐Brücken

Abstract

Koordinationschemie mit den komplexen Chelatliganden[ {Fe2Cp2(CO),>2{CN[CH2]nNC>] (n = 2, 3). Heteropentanukleare ,,Superkomplexe" mit p5-Diisocyanid-Brucken" Coordination Chemistry with the Complex Chelating Ligands [(Fe2Cp2(CO)3)2(CN[CH2]nNC]] (n = 2, 3). Heteropentanuclear "Supercomplexes" with ps-Diisocyanide Bridges"' The tetranuclear complexes [(Fe,Cp,(CO),(p-CO) J2(p4-tra. Reaction of 2 with [Ni(COD),] in CHzClz gave only rise CN[CH2],NC)] [n = 2 (2), 3 (3)] act as bidentate chelating to the dichloronickel(I1) species 9a. Very remarkably, the ligands towards the Lewis-acidic metal halides MnC12, pentairon complex [ (Fe2Cp2(CO),(p-CO))2{p5-CN(CH2)2-MnBr,, FeC12, CoCIz, NiCl,, NiBr2, CuCl,, CuBrz, ZnC12, NCJIFeCl, (7) also formed spontaneously (!) when 2 was re-ZnI,, CdC12, CdI2, HgCl,, the chloro complexes [MClZ-fluxed in chloroform for several hours. The X-ray structure (NCPh),] (M = Pd, Pt), Zn(OAc)z . HzO, and [Mo(CO),( q-analysis of [(Fe2Cp2(CO)z(p-CO))~{p5-CN(CH2)2NC}]CdI,NBD)) (NBD = 2,5-norbornadiene) to give a total of 22 penta-(14b) confirms the twofold p3-(C,C,N) bridging mode of a dinuclear "superconiplexes" 6-21, which have been characte-isocyanide ligand in a cis/cis-anfi-configurated [Fe&Cd penrized by elemental analyses and IR and NMR ('H, I3C) spec-tanuclear system of crystallographic C2 symmetry. * noch erscheinen die Ligandenqualitaten von 1 -sein Raumbedarf, seine Starrheit und sein nur maDiges Donorvermogen stehen einer forcierten ,,Superkomplex"-Bildung entgegenverbesserungswurdig. Im folgenden beschreiben wir Metallkomplexe mit den ,,Chelatliganden" [{ Fe2Cp2-(C0)3}2CN[CH2],NC] [n = 2 (2), 3 (3)], bei denen die genannten Defizite wesentlich gemildert sind.

Aminocarbyne ligands in organometallic chemistry

“…A comparative view of the X-ray structures of cationic aminocarbyne complexes based on the Fe2Cp2(CO)x scaffold (x = 2 or 3) is provided in Figure 6. A special case is represented by bidentate diisocyanide ligands, which generate a tetranuclear scaffold by bridging two {Fe2Cp2(CO)3} units [112,113]. The 1,2-diisocyanoethane ligand undergoes a double alkylation with excess [Me3O]BF4 to afford the bis-aminocarbyne [Fe2Cp2(CO)3{μ-CN(Me)CH2}]2 (40d).…”

“…Protonation of isocyanides in di-and tri-metallic compounds is usually carried out with strong, poorly coordinating, Brønsted acids such as CF3SO3H, HPF6, HBF4, HClO4, HI, HCl or [HOEt2][BAr F ], in mixed aqueous-organic or in strictly anhydrous organic solvents [93,103,112,113,172,173,200,201,202,203,204]. Compound [{Fe2Cp2(CO)3}2(μ-1,2-diisocyanobenzene)] is another stark example of different behavior towards protonation and alkylation.…”

“…Lewis acids other than protonating and classical alkylating agents may react with isocyanide complexes to form aminocarbyne-like species. The addition to isocyanides of a range of metal dihalides and boranes yield, respectively, 'metallaaminocarbynes' and 'borataaminocarbynes', which might be viewed as bi-or tri-metallic units bridged by a C,N isocyanide moiety and will not be discussed further [112,113,235,236,237,238,239]. An overview of 2-aminocarbyne-like ligands derived from the possible isocyanide-Lewis acid combinations is given in Scheme 43.…”

“…In this respect, a rather wide range of CN stretching wavenumbers has been reported (1640-1300 cm -1 ). In particular, compounds [Co3Cp3(μ3-S)(μ3-CNRR')] + (112) are very sensitive to the nature of the N-substituents, showing a CN band around 1500 cm -1 with alkyl groups, moving down to 1300 cm -1 with electron-withdrawing aryl groups [251].…”

ansa-Chromocene Complexes. 2. Isocyanide Derivatives of Cr(II) and Cr(III), Their Syntheses, X-ray Crystal Structures, and Physical Properties

“…Isocyanide ligands are often interchangeable with CO in transition metal complexes, although they are, in general, better σ-donors and poorer π-acceptors than CO. , They are also similar to CO in their usefulness for probing the electron-donating/accepting properties of the metal, which is manifested in the energy of the C−N stretching vibration, the bond angle about nitrogen, and the 13 C and 15 N NMR chemical shifts of the ligands. , Isocyanide ligands are more versatile ligands than CO in the sense that the substituent on nitrogen can be varied to influence the donor/acceptor properties of the ligand and to manipulate the architectures of metal complexes that are constructed with the ligand. For example, bridging diisocyanide ligands have been used to support a variety of dinuclear metal−metal bonded species − as well as metal-containing macrocycles and polymers. − …”