4-(Ferrocenylmethyl)-2,2,6,6-tetramethyl-3,5-heptanedione, a non-enolized 1,3-diketone

Abstract

Program(s) used to solve structure: SHELXTL-Plus (Sheldrick, 1991). Program(s) used to refine structure: SHELXL93 (Sheldrick, 1993 AbstractThe analysis of the title compound, (r/5-cyclopentadien -shows that it exists in the solid state in the diketo form; there is no evidence at all for any keto-enol tautomeric contribution to the ground-state structure. CommentBoth in solution and in the vapour phase (Lowrey, George, D'Antonio & Karle, 1971), 1,3-diketones R'COCH2COR" generally exist as equilibrium mixtures of keto and enol tautomers where the enol tautomer contains a six-membered hydrogen-bonded ring.In the solid state, however, only a single form is generally observed. This is most frequently the enol form in which the hydrogen-bonded ring is virtually planar with the two C---O bonds necessarily cis (T~nnesen, Karlsen & Mostad, 1982;TCnnesen, Karlsen, Mostad, Pedersen, Rasmussen & Lawesson, 1983;Etter, Jahn & Urbanczyk-Lipkowska, 1987;Baxter, Blake, Heath & Stephenson, 1990 (Gyepes, Glowiak, Toma & Sold~inov~i, 1984) the ring containing the 1,3-diketone fragment is twisted severely as a result of the ring strain in the [3]ferrocenophane skeleton, so that enolization is again prevented. However, in the acyclic diketone 2-ethyl-1,3-diphenyl-l,3-propanedione, (PhCO)2CHC2H5 (MuUica, Karban & Grossie, 1987), the solid-state structure again indicates a complete lack of enolization associated with a markedly non-planar O==C~C---C==O fragment, although 1,3-diphenyl-1,3-propanedione itself is wholly in the enol form in both crystalline modifications (Jones, 1976a;Etter, Jahn & Urbanczyk-Lipkowska, 1987). In a study of the 1-ferrocenyldiketone [(CsHs)Fe-{(CsH4)COCH2COCH3}], it was found (Bell, Crayston, Glidewell, Mazid & Hursthouse, 1992) that in chloroform solution the enol:keto ratio was ca 17:1, but in the solid state both XSC CP-MAS (cross-polarization magic angle spinning) NMR and X-ray diffraction revealed only the enol form, 1-ferrocenyl-3-hydroxybut-2-en-l-one. In contrast, the 4-ferrocenylmethyl derivative [(CsHs)Fe{(CsHn)CH2CH(COCMe3)2}] (I) exhibits an enol:keto ratio in chloroform solution of 1:3 (Zakaria, Morrison, McAndrew, Bell & Glidewell, 1994), suggesting that, like (PhCO)2CHC2Hs, it might exist in the solid state solely in the diketo form. Here we report a single-crystal X-ray study of this compound which confirms that in the solid state it is indeed a non-enolizedCompound (I) crystallizes in the triclinic system (space group Pi) with one molecule in the asymmetric unit. The structure comprises isolated molecules with no short intermolecular contacts. In the --CH2CH(COCMe3)2 substituent, the C2---C3 and C2--C5 bond lengths (Table 2, Fig. 1) are typical of those in unenolized 1,3-diketones (range 1.507-1.537 ,~; Gyepes, Glowiak, Toma & Sold~inov~i, 1984;Gyepes, Glowiak & Toma, 1986;Mullica, Karban & Grossie, 1987), whereas in enolized 1,3-diketones the corresponding C---C distances lie in the range 1.34-1.43/~ (Bell, Crayston, Glidewell, Mazid & Hursthouse, 1992).The C3---O1 and C5----O2 distance...

Synthesis, characterization and X-ray crystal structures of chiral ferrocene-containing β-diketones

“…In agreement with FT-IR and NMR data (see Sections 2 and 3.1), the crystal structures confirm that the three complexes 1-3 exist solely as their diketo tautomer. The measured C(14)-O(1) and C(16)-O(2) bond lenghts (see Table 2) are typical of C=O double bonds [24], as found for another structurally characteerized non-enolized 1,3-diketone [25]. Moreover, the C-C bond distances (> 1.52 Å) and angles (~ 110°) around the central C(13) carbon are those expected for a sp 3 -hybridized carbon atom (Table 2) (Table 3), whereas intermolecular C-H•••O hydrogen bonds (Table 4) generate a dimeric unit in compound 2 creating a plane of symmetry between the molecules, and a chain structure in complex 3 (Fig.…”

Methyl 4-{[(1Z)-1-benzoyl-3-oxo-3-phenylprop-1-en-1-yl]amino}benzoate

“…-Diketone complexes of transition metals have been the subject of many different studies ranging from synthetic (Pedersen et al, 1959;Weinmayr, 1958), kinetic (Leipoldt, Basson et al, 1991;Leipoldt, Lamprecht & Steynberg, 1991;Leipoldt & Grobler, 1986) and structural (Roodt et al, 1992;Ferguson et al, 1994;Haaland & Nilsson, 1968;Yogev & Mazur, 1967) topics to catalysis (Cullen et al, 1991;Cullen & Wickenheiser, 1989) and many others (Stary, 1964;Mehrotra et al, 1978). Our research involves the synthesis of -diketones with different functionalities (du Plessis et al, 1999) and the complexation of these -diketones to metals (Lamprecht et al, 1993;Conradie et al, 2002Conradie et al, , 2005 for use in the study of model catalyst systems.…”

Molecular and Solid State Structure of the Doubly-Substituted B-Diketone 3,3'-Bis(ferrocenylmethyl)pentane-2,4-Dione#

“…27,37 The lengths of the C-C in the connecting tetrahedral core, and of the C-C and C-Fe bonds in the ferrocene sandwiches (see Table 2) fall all within the range of standard values. 36,38 The bond angles at the central carbon C (12) Within the crystal structure of 2 there are several short intermolecular contacts.…”