Über 1.2.3.4‐Tetrachlorcyclopentadien‐(1.3)

Abstract

1.2.3.4‐Tetrachlor‐cyclopentadien‐(1.3) wird aus Hexachlor‐cyclopentadien durch Reduktion mit Zinkstaub in Eisessig dargestellt. Die Verbindung addiert leicht Chlor und Brom, reagiert glatt mit verschiedenen dienophilen Komponenten und kuppelt mit Diazoniumsalzen bereits in stark saurem Medium. Unter den gleichen Bedingungen läßt sich das Tetrachlor‐cyclopentadien an der Methylengruppe oximieren. Die letztgenannten Reaktionen deuten auf eine hohe C–H‐Acidität der Methylengruppe hin.

Unusual chemical reactivity in the reactions of Re2(CO)8(μ-H)(μ-η1,η2-CHCHBu) with 2,3-bis(diphenylphosphino)maleic anhydride (bma) and Re2(CO)8(bma) with Ni(cod)2: X-ray diffraction structures of Re2(CO)8(bma), zwitterionic Re(CO)4[Re(CO)4(bma)], and the phosphido-bridged complex Re2(CO)8[μ-η1,η1-(O)](μ-PPh2)

“…The ORTEP diagram of Re 2 (CO) 8 Fig. 1 confirms the bridging of the Re-Re vector by the bma ligand and the staggered arrangement of the equatorial groups about the Re-Re bond [24].…”

“…The latter chemical was prepared from Ph 2 PH and TMSCl [8], while the Re 2 (CO) 10 was prepared from NaReO 4 and CO, employing the carbonylation procedure of Heinekey [9]. The hexenyl compound Re 2 (CO) 8 (l-H)(l-g 1 ,g 2 -CH@CHBu) (1) was obtained from the photochemical reaction of Re 2 (CO) 10 and 1-hexene, as originally described by Brown [10].…”

“…Both reductions are chemically reversible given the linear plots of the current function (I p ) vs the square root of the scan rate (m) and the near unity current ratios (I a p =I c p ) over the scan rates investigated [32]. The electron Table 2 Selected bond distances ( A) and angles (°) in the dirhenium compounds 2-4 a Re 2 (CO) 8 …”

“…Given the dearth of structurally characterized rhenium complexes that contain an ancillary bma ligand, we have embarked on the synthesis and study of other such rhenium complexes [6]. Herein we present our data on the reaction between the activated hexeny compound Re 2 (CO) 8 (l-H)(l-g 1 ,g 2 -CH@CHBu) and bma, which affords Re 2 (CO) 8 (bma) (2) and Re(CO) 4 [Re(CO) 4 (bma)] (3). The cleavage of the P-C bond in 2 by added Ni(cod) 2 gives the corresponding phosphidobridged dirhenium compound Re 2 (CO) 8 [l-g 1 ,g 1 -(O)](l-PPh 2 ) (4).…”

“…Herein we present our data on the reaction between the activated hexeny compound Re 2 (CO) 8 (l-H)(l-g 1 ,g 2 -CH@CHBu) and bma, which affords Re 2 (CO) 8 (bma) (2) and Re(CO) 4 [Re(CO) 4 (bma)] (3). The cleavage of the P-C bond in 2 by added Ni(cod) 2 gives the corresponding phosphidobridged dirhenium compound Re 2 (CO) 8 [l-g 1 ,g 1 -(O)](l-PPh 2 ) (4). Compounds 2-4 have been fully characterized in solution and their molecular structures established by X-ray crystallography.…”