on the occasion of his 65th hirthday
The recently reported successful stabilization of cyclo-As5 and cyclo-P, ("hexaphosphabenzene") as bridge ligand ("middle deck") in the triple-decker complexes l"] and 2") respectively, signaled the possibility of also stabilizing cvclo-P, in the same way.[31
If, in analogy to the synthesis of 2, the Cr,-complex 3 is allowed to react with P4, then not only traces of the yellow q3-P3-complex 4 are formed but also the p,q'-P, tripledecker complex 5, which can be isolated as blackish-red, shiny-metallic crystals (dec. 250°C).L4.'71 xylene 140 O C . 2 h ! p4 Cr I Cr Me -&Me Me Me 5 5,I4I which is only sparingly soluble in pentane but moderately soluble in benzene and dichloromethane (the solu- tions are very air-sensitive), is a paramagnetic triple-decker complex.['] With 27 valence electrons (3 x 5 and 2 x 6), 5 closes a gap, since up to now only examples with 26 and 28 to 34 valence electrons were known.[6,'61 In the 'H-NMR spectrum (200 MHz, 293 K, CDCI,, TMS int.), a broad signal (halfwidth = 30 Hz) is observed at 6= -7.1 (paramagnetic shift), in the "P( 'H)-NMR spectrum (80.82 MHz, [D,]benzene, 85% H3P04 ext.), a sharp singlet at 6=290.5 ('3C('H)-NMR (50.28 MHz, [D,]benzene, TMS int.): 6= 80.4 (s, C,Me,), -2.2 (s, CH,)). In the mass spectrum,['] the line for the molecular ion is the strongest-intensity line.