Reactivity Studies of Methylzirconocene Phosphide Complexes

Abstract

The reaction of Cp2ZrMe(PHR) with benzophenone, cyclohexanone, acetone, benzaldehyde, and benzophenone results in the insertion of the organic substrate into the Zr−P bond. In this way, the complexes Cp2ZrMe(OCPh2PH(C6H2-2,4,6-t-Bu3)) (3), Cp2ZrMe(OC6H10PH(C6H2-2,4,6-t-Bu3)) (4), Cp2ZrMe(OCMe2PHR) (R = (C6H2-2,4,6-t-Bu3) (5), R = (C6H2-2,4,6-Me3) (8), and Cp2ZrMe(NC(Ph)PH(C6H2-2,4,6-t-Bu3)) (6) were prepared. The species Cp2ZrMe(PH(C6H2-2,4,6-Me3)) (7) was also formed in the reaction of Cp2ZrMe2 with H2P(C6H2-2,4,6-Me3); however, 7 reacted further with Cp2ZrMe2 to give the bimetallic species (Cp2ZrMe)2(μ-P(C6H2-2,4,6-Me3) (9). In the analogous reaction of Cp2ZrMe2 with 1 equiv of H2P(C6H2-2,4,6-Me3), the species (Cp2Zr)(Cp2ZrPH(C6H2-2,4,6-Me3))(μ-P6H2-2,4,6-Me3))(μ-η1-η5-C5H4) (11) was obtained. Compound 11, which results from cyclopentadienyl C−H bond activation, was also formed directly from degradation of the unstable terminal phosphinidene species Cp2Zr(P(C6H2-2,4,6-Me3))(PMe3) (12). The implications of this chemistry are considered and discussed. Compound 3, 9, and 11 have been characterized crystallographically.

Phosphinidene-bridged binuclear complexes

“…In a similar study, the methyl complex [ZrCp 2 Me 2 ] was reacted with PH 2 Mes [45]. The stoichiometric reaction in refluxing toluene led to the formation of the phosphanyl phosphinidene complex 37 in ca.…”

From Dinuclear Zirconium(+3)‐Phosphido Complexes {[Cp2ZrP(H)R]2} to the First Neutral Zirconocene–Phosphinidene Dimers [(Cp2ZrPR)2] by P–H Dehydrogenation

“…[15] The 31 P chemical shifts of 3a-3c are similar to the values of the hitherto only known neutral zirconium phosphinidene complexes C (δ = 325.5, 303.0 ppm; see Figure 1). [4,16] The 1 H, 31 P, and 13 C NMR spectra of the products clearly indicate that there is only one configurational isomer present in solution even at low (-75°C) and high temperatures (+85°C). The composition of the novel complexes were confirmed by mass spectrometry and correct elemental analyses.…”

Zirconium - Phosphorus Chemistry: Strategies in Syntheses, Reactivity, Catalysis, and Utility

“…[34,39,40] The analogous insertion of phenylacetylene afforded 18, [41] and further substitution with phenylacetylide anion gave 19. [42] We showed that ketones, aldehydes, and nitriles also insert into the ZrÀP bonds of [Cp 2 ZrMe(PHMes*)] (Mes* 2,4,6-tBu 3 C 6 H 2 ) to give products of the type F (R Ph; R' Ph, H) and G. [11] In a similar Di-and triphosphanato complexes also exhibit facile ZrÀP acidolysis and insertion reactions. For example, hydrolysis of [Cp 2 Zr{(PPh) 2 }] gave the diphosphanes (PHR) 2 .…”

“…[11] Recently, Hey-Hawkins et al extended PÀH bond activation to monocyclopentadienyl Zr complexes. [79] Treating LiPHtBu with [{CpZrCl 3 } n ] results in a redox reaction in which Zr is partially reduced and the phosphanido group is oxidized to (PHtBu) 2 .…”