An Inverted-Sandwich Diuranium μ-η(5):η(5)-Cyclo-P5 Complex Supported by U-P5 δ-Bonding.
Reaction of [U(Tren(TIPS))] [1, Tren(TIPS)=N(CH2CH2NSiiPr3)3] with 0.25 equivalents of P4 reproducibly affords the unprecedented actinide inverted sandwich cyclo-P5 complex [{U(Tren(TIPS))}2(μ-η(5):η(5)-cyclo-P5)] (2). All prior examples of cyclo-P5 are stabilized by d-block metals, so 2 shows that cyclo-P5 does not require d-block ions to be prepared. Although cyclo-P5 is isolobal to cyclopentadienyl, which usually bonds to metals via σ- and π-interactions with minimal δ-bonding, theoretical calculations suggest the principal bonding in the U(P5)U unit is polarized δ-bonding. Surprisingly, the characterization data are overall consistent with charge transfer from uranium to the cyclo-P5 unit to give a cyclo-P5 charge state that approximates to a dianionic formulation. This is ascribed to the larger size and superior acceptor character of cyclo-P5 compared to cyclopentadienyl, the strongly reducing nature of uranium(III), and the availability of uranium δ-symmetry 5f orbitals.
School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD (UK).
Benedict M
BM
Gardner
School of Chemistry and Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL (UK).
Floriana
F
Tuna
School of Chemistry and Photon Science Institute, University of Manchester, Oxford Road, Manchester, M13 9PL (UK).
Eric J L
EJ
McInnes
School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD (UK).
Jonathan
J
McMaster
School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD (UK).
William
W
Lewis
School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD (UK).
Alexander J
AJ
Blake
School of Chemistry, University of Nottingham, University Park, Nottingham, NG7 2RD (UK). stephen.liddle@nottingham.ac.uk.
Stephen T
ST
Liddle
cyclo-P5; density functional theory; phosphorus; uranium; δ bonding