Synthesis and characterization of bis(diphenylphosphido)bis(pentamethylcyclopentadienyl)thorium(IV), [(.eta.5-C5(CH3)5]2Th(PPh2)2

Abstract

Synthesis and Characterization of Bis( diphenylphosphido) bis( pentamethylcyclopentadieny1)-thorium ( I V ) , [ (q5-C5( CH&],Th( PPh,),The first diorganophosphido actinide complexes Cp*2Th(PRZ), (Cp* = T~-C~( C H~)~, R = Ph, Cy, Et) have been prepared by reaction of Cp*zThC12 with LiPR2. These complexes have been characterized spectroscopically, and Cp*zTh(PPh2)z has been structurally characterized by a complete single-crystal X-ray diffraction study. This compound crystallizes in the space group P2,/c with a = 35.071 (8) A, b = 15.203 (6) A, c = 21.840 (11) A, ( 3 = 92.97 ( 2 ) O , at T = -95 "C, and V = 11629.3 A3 and 2 = 12 (Mo Ka, radiation, X = 0.709 30 A). The structure refined to RF = 0.08 and RwF = 0.07. There are three crystallographically independent molecules in the asymmetric unit. All three molecules exhibit pseudotetrahedral geometry about the thorium atom with the pentamethylcyclopentadienyl ligands and two diphenylphosphido groups occupying the four coordination sites. While the angles about the phosphorus atoms are far from the tetrahedral, there is no evidence for significant Th-P multiple bonding. The average Th-P distance is 2.87 (2) A. (1) (a) Bruno, J. W.; Huffman, J. C.; Green, M. A.; Caulton, K. G. J . Am. Chem. SOC. 1984,106,8310. (b) Casey, C. P.; Jordan, R. F.; Rheingold, A. L. Ibid. 1983,105,665. (c) Wrobleski, D. A.; Day, C. S.; Goodman, B. A.; Rauchfuss, T. B. Ibid. 1984,106,5464. (d) Rosenburg, S.; Whittle, R. R.; Geoffroy, G. L. Ibid. 1984, 106,5934. (e) Breen, M. J.; Shulman, P. M.; Geoffroy, G. L.; Rheingold, A. L.; Fultz, W. C. Organometallics 1984, 3, 782. ( f ) Regragui, R.; Dixneuf, P. H.; Taylor, N. J.; Carty, A. J. Ibid. 1984,3,814. (9) Chandler, D. J.; Jones, R. A.; Stuart, A. L.; Wright, T. C.

Thorium–phosphorus triamidoamine complexes containing Th–P single- and multiple-bond interactions

“…The Th–P bond distance in 2 is in good agreement with the sum of the single-bond covalent radii for thorium and phosphorus67, but is relatively long for a thorium(IV)–phosphanide bond545556575859. However, this can be rationalized on the sterically demanding Tren TIPS ligand whereas all other thorium(IV)–phosphanide complexes involve a bis (pentamethylcyclopentadienyl) ligand combination that presents a sterically more accessible wedge for phosphanide ligation545556575859. Interestingly, the Th–P bond is ∼0.05 Å longer than might be expected from the difference in covalent radii of thorium and uranium67 when compared with the parent uranium(IV)–phosphanide congener34, which may reflect a more ionic Th–P interaction compared with the U–P interaction as suggested by calculations (see below).…”

“…The Th–P bond distance in 2 is in good agreement with the sum of the single-bond covalent radii for thorium and phosphorus67, but is relatively long for a thorium(IV)–phosphanide bond545556575859. However, this can be rationalized on the sterically demanding Tren TIPS ligand whereas all other thorium(IV)–phosphanide complexes involve a bis (pentamethylcyclopentadienyl) ligand combination that presents a sterically more accessible wedge for phosphanide ligation545556575859.…”

“…2.866 Å), [Th(η 5 -C 5 Me 5 ) 2 {P(SiMe 3 ) 2 }(Me)] (2.888(4) Å) and [Th(η 5 -C 5 Me 5 ) 2 (HP-2,4,6-Pr i 3 C 6 H 2 ) 2 ] (av. 2.879 Å) (refs 54, 55, 56, 57, 58, 59). The Th–P distance in 2 can also be compared with the U-P distance in the uranium analogue (2.883(2) Å) (ref.…”

“…For example, under ambient conditions there are only a handful of each class of structurally authenticated formal Th=C carbene134445, Th=N imido464748 and terminal Th=O oxo or Th=E···K (E=O, S, Se, Te) complexes495051 known; where thorium–phosphorus multiple bonds are concerned, they are conspicuous by their absence outside of cryogenic matrix isolation experiments52. Indeed, of fewer than thirty crystallographically authenticated thorium–phosphorus complexes in the Cambridge Structural Database53 seven are phosphanides54555657585960, three are polyphosphides6162, one is a phosphinidiide54, a term we use to indicate its bridging nature, and the remainder are phosphine derivatives; a dithorium-phosphinidiide complex [{Th(η 5 -C 5 Me 5 ) 2 (OMe)} 2 (μ-PH)] (ref. 36) has been described though not structurally confirmed.…”

Dimorphism in Actinide Phosphides: Tetrakis[bis(2-dimethylphosphinoethyl)phosphido]thorium(IV)

“…The metal-ligand bond lengths correspond well with those found for the previously reported dimorph (Edwards, Harman, Hursthouse & Parry, 1992 (Wrobleski, Ryan, Wasserman, Salazer, Paine & Moody, 1986 (Edwards, Andersen & Zalkin, 1984). The difference between the average lengths of the formally anionic phosphidothorium bonds and the formally neutral phosphinothorium bonds is as expected (Domaille, Foxman, McNeese& Wreford, 1980).…”