Absolute configuration of organometallic compounds. 4. X-ray determination of the structure and absolute configuration of (-)579-(.eta.5-C5H5)Fe(CO)[P(C6H5)3]COOC10H19

Abstract

The structure and the absolute configuration of (-)s79-(75-C5H5)Fe(CO)[P(C6H5)3]COOC10H19 (C10H19 = menthyl) have been determined by single-crystal x-ray diffraction methods using data acquired by a computer-controlled diffractometer and Bijvoet's technique. The substance crystallizes in the orthorhombic system, space group P2,2121, with cell constants of a = 11.221 (4), b = 14.817 (7), and c = 18.958 (3) Á. The observed and calculated densities are 1.25 (2) and 1.25 g/cm3 (for Z = 4 molecules/unit cell). The Fe-(i)5-C5H5) fragment has normal distances and angles and the Cp ring is planar, as expected. The Fe-P(C6H|)3 group has stereochemical parameters which are well within the values found in the literature (i.e., Fe-P = 2.214 (2) A, P-C = 1.830 (6), 1.838 (4), and 1.853 (6) Á), and the dihedral angles of the three phenyl rings are canted at arbitrary values dictated by packing. The most important features of the stereochemistry of the molecule are the following: (1) the Fe-C(C=0) and C=0 distances are, respectively, 1.670 (7) and 1.206 (9) Á. . The former is the shortest iron to carbonyl carbon distance observed thus far. (2) The Fe-ester fragment shows a large angular distortion at the C atom such that Fe-C=0 = 132.1 (5), Fe-C-OC10Hi9 = 117.7 (4), and 0=C-O = 108.8(5)°. Concomitant with this distortion is a shortening of the Fe-C(ester) bond to 1.825 (6) Á. Both of these observations point to an enhanced r-bonding interaction between the iron atom and the carbons of the carbonyl and ester group. When the current rules for ranking groups are applied, the configuration at the iron atom is specified to be 5.

Optically Active Organometallic Compounds of Transition Elements with Chiral Metal Atoms

“…These angles are frequently close to the octahedral angle of 908. [32] 4. Square-Pyramidal, Octahedral, and Tetrahedral Complexes with an Asymmetric Metal Atom…”

Optisch aktive metallorganische Verbindungen der Übergangselemente mit chiralen Metallatomen

“…Dies geht auch aus den Winkeln hervor, die die einzähnigen Liganden miteinander bilden: Sie liegen häufig nahe am Oktaederwinkel von 908. [32] 4. Quadratisch-pyramidale, oktaedrische und tetraedrische Komplexe mit asymmetrischem Metallatom…”

“…[45,46] Tetraedrische Komplexe und Halbsandwichkomplexe des Dreibein-Klavierstuhl-Typs gehören nach Ruch [47] zur Chiralitätsklasse a, für die eine achirale Grenze zwischen (R) und (S) existiert. Verbindungen mit quadratisch-pyramidalen und oktaedrischen Gerüsten dagegen gehören zur Chiralitätsklasse b, für die es keine solche achirale Grenze gibt.…”

“…[54] Diese chiroptischen Daten weisen auf eine Bild-Spiegelbild-Beziehung zwischen Ausgangsmaterial und Produkt und damit auf einen Inversionsmechanismus hin, der durch die röntgenstrukturanalytische Bestimmung der absoluten Konfiguration am Eisenatom in Ausgangsmaterial und Reaktionsprodukt bestätigt wurde. [45,46,55] Abbildung 6. Inversion der Konfiguration bei der Reaktion von 4 a mit LiCH 3 zu 16 b. CD-Spektren von 4 a und 16 b (Konzentrationen etwa 10 À3 mol L À1 in Benzol).…”

Structure of an acetylcarbonylcyclopentadienyliron complex with a phosphine ligand. I. (η-MeC5H4)Fe(CO)(COMe)(PPh2Et)

“…A form 2.106 (1) 1.748 (6) 1.968 (5) 2.102 1.740 B form 2.110 (1) 1.724 (6) 1.957 (6) 2-094 1.767 (i) References: (a) this paper; (b) Korp & Bernal (1981); (c) Reisner, Bernal, Brunner & Muschiol (1978) factors are from International Tables for X-ray Crystallography (1974). Computations were done with the UCLA Crystallographic Program Package (Strouse, 1978) as modified at Argonne National Laboratory.…”