2,4,6-Tri-tert-butyl-1,3,5-triphosphabenzene as an η6-Ligand in Transition Metal Complexes

Abstract

The η6‐1,3,5‐triphosphabenzene transition metal complexes 12a,b, 14, and 16 have been synthesized for the first time by the displacement of η6‐arene ligands (toluene, benzene and naphthalene) with 2,4,6‐tri‐tert‐butyl‐1,3,5‐triphosphabenzene (9). The new complexes have been fully characterized by a combination of elemental analysis, mass spectrometry, and 1H‐, 13C‐ and 31 P‐NMR spectroscopy.

Differences in the η1-ligating properties of 2,4,6-tritertiarybutyl-phosphabenzene, and 2,4,6-tritertiarybutyl-1,3,5-triphosphabenzene,

“…Yield = 180 mg, 73%. 1 H NMR (400 MHz, CD 2 Cl 2 ): 8.10, 8.05 (m, ring H's), 1.96 (m, 6H, P{CH 2 CH 3 } 3 ), 1.79 (s, 18H, Bu t ), 1.39 (s, 9H, Bu t ), 1.27, 1.23 (2 overlapping t, 9H, P{CH 2 CH 3 } 3 , 7.61 Hz). 31 3 Â 10 À4 mol) and 5 (0.044 g, 6.5 Â 10 À5 mol) were combined, dissolved in toluene and stirred vigorously for 24 hours.…”

“…Although previous studies have shown that the 2,4,6-tritertiarybutyl-1,3,5-triphosphabenzene ring 1 readily acts as a 6p-electron donor towards metal centres [1][2][3], the only reported examples of g 1 -bonded metal complexes are trans-[PtCl 2 (PR 3 )(g 1 -P 3 C 3 Bu t…”

Unprecedented triphosphinine iron interactions: Intramolecular electron transfer, reactivity round a corner, and a low-activated ring element exchange reaction

“…In the light of that result, identity of the 31 P spin systems of diamagnetic 12 and radical 7 À is not accidental, but reflects the single respectively double occupancy of analogous orbitals, which cause the distortions of 7 À and 12. This finding represents a strong contrast to the formal Ru-analogue of 12 [(h 4 -1,5-COD)(h 6 -2,4,6-tri-tert-butyl-1,3,5-triphosphinine)Ru] (14) [15]. As for other (h 6 -2,4,6-tri-tert-butyl-1,3,5-triphosphinine)Ru complexes [29], 14 appears to be a classical (h 6 -1,3,5-triphosphinine)M (0) complex with a planar and C 3 -symmetric heteroarene ligand.…”

“…The calculated molecular structure of 8c(t) seems to be somewhat strange; however, it is isoenergetic with 8b(t) and there exists a case of precedence. A reversible interligand bond forming process of that kind has been observed between two of the p-ligands of tris(2,4-di-tertbutyl-1,3-diphosphete)Mo (15) [30]. This specific reactivity was rationalized as a consequence of a pronounced ambiphilicity of p-bound unsaturated P-heterocycles.…”

“…The availability of free 7 allowed ligand displacement reactions of some Mn, Mo, W, and Ru (h 6 -arene)M complexes with hydrocarbon ligands to yield the related [(h 6 -2,4,6-tri-tert-butyl-1,3,5-triphosphinine)ML n ] complexes. They are stable compounds [15]. PES spectroscopy and DFT calculations of free 7 as well as a series of [(h 6 -2,4,6-tri-tert-butyl-1,3,5-triphosphinine)M(CO) 3 ] (M = Cr, Mo, W) complexes gave clear hints on the impact of the three phosphorus atoms on the electronic properties of the benzene ring system.…”