Synthesis and reactivity of the uranium phosphinidene metallocene [η⁵-1,3-(Me₃Si)₂C₅H₃]₂U(P-2,4,6-ⁱPr₃C₆H₂)(OPMe₃): influence of the coordinated Lewis base

Abstract

This paper describes the synthesis and reactivity of [5-1,3-(Me3Si)2C5H3]2U(=P-2,4,6-iPr3C6H2)(OPMe3) (6) which is accessible from a ligand exchange reaction between [5-1,3-(Me3Si)2C5H3]2U(=P-2,4,6-iPr3C6H2)(OPPh3) (2) and Me3PO at ambient temperature. Phosphinidene 6 exhibits no...

Small-Molecule Activation Mediated by [η5-1,3-(Me3Si)2C5H3]2U(bipy)

“…1 H NMR (C 6 D 6 ): δ 86.72 (s, 4H, ring C H ), 83.36 (s, 2H, ring C H ), −0.73 (s, 36H, Si­(C H 3 ) 3 ), −13.81 (s, 36H, Si­(C H 3 ) 3 ), −86.01 (s, 4H, ring C H ), −90.06 (s, 2H, ring C H ) ppm. These spectroscopic data agreed with those reported in the literature …”

“…Addition of pyridine N -oxide (pyO) to 2 yields the known dimeric uranium oxido species {[η 5 -1,3-(Me 3 Si) 2 C 5 H 3 ] 2 U} 2 (μ-O) 2 ( 9 ), ,, free pyridine (py), and free bipy (Scheme ). We propose that similar to the reactivity of the uranium bipyridyl metallocene [η 5 -1,2,4-(Me 3 C) 3 C 5 H 2 ] 2 U­(bipy), pyO reacts initially with 2 to displace bipy and to yield the oxido uranium pyridine adduct [η 5 -1,3-(Me 3 Si) 2 C 5 H 3 ] 2 UO­(py) .…”

“…The U–N(2) and U–N(3) distances in 12 are 2.711(10) and 2.630(10) Å (Figure and Table ), respectively, whereas the U–N(1) distance is 2.013(9) Å, close to that found in [η 5 -1,2,4-(Me 3 C) 3 C 5 H 2 ] 2 UN­( p -tolyl) (1.988(5) Å) . Moreover, two-electron transfer processes are also encountered in the reactions of 2 with 1 equiv of CS 2 or PhNCS, from which the known dimeric uranium sulfido complex {[η 5 -1,3-(Me 3 Si) 2 C 5 H 3 ] 2 U} 2 (μ-S) 2 ( 14 ) are exclusively isolated, along with concomitant extrusion of bipy, and “CS” or PhNC, respectively (Scheme ). Hence, complex 2 effectively cleaves the CS bonds of CS 2 and PhNCS to form the sulfido metallocene [η 5 -1,3-(Me 3 Si) 2 C 5 H 3 ] 2 US and carbon monosulfide “CS” or isonitrile PhNC, respectively, but the monomeric sulfido intermediate rapidly dimerizes to the thermodynamically more stable product 14 (Scheme ).…”

“…Furthermore, while the bipyridyl ligand in complex (η 5 -C 5 Me 5 ) 2 U­(bipy) is cleanly replaced by imine PhCHNPh, the reaction of 2 with PhCHNPh furnishes an insertion product [η 5 -1,3-(Me 3 Si) 2 C 5 H 3 ] 2 U­[(bipy)­(PhCHNPh)] ( 19 ). Clearly, the steric bulk exerted by the individual cyclopentadienyl ligands has a dominating influence on the reaction products obtained, with the C 5 Me 5 derivative being more sterically demanding than 1,3-(Me 3 Si) 2 C 5 H 3 . However, at the same time, electronic effects cannot be completely discounted.…”

“…Gratifyingly, these compounds can be utilized in a broad array of different reactions in which they serve as Cp 2 An­(II) transfer reagents . So far, we have mainly focused on alkyl-substituted Cp ligand, but we wondered if the reactivity of such species might be modulated with the less sterically demanding and more electron-deficient 1,3-bis­(trimethylsilyl)­cyclopentadienyl ligand 1,3-(Me 3 Si) 2 C 5 H 3 . It is also of note that Evans and co-workers employed this ligand to prepare well-defined An­(II) compounds of the type {[1,3-(Me 3 Si) 2 C 5 H 3 ] 3 An} − . ,− , Therefore, the synthesis of [η 5 -1,3-(Me 3 Si) 2 C 5 H 3 ] 2 U­(bipy) ( 2 ) and its reactivity toward small molecules are described herein.…”