257619-59-3Relevant academic research and scientific papers
Experimental evidence for magnetic exchange in Di-and trinuclear uranium(IV) ethynylbenzene complexes
Newell, Brian S.,Rappe, Anthony K.,Shores, Matthew P.
, p. 1595 - 1606 (2010/04/25)
We report the preparation andmagnetic property investigations of a structurally related family ofmono-, di-, and trinuclear U(IV) aryl acetylide complexes. The reaction between [(NN 3)UCl] and lithiated aryl acetylides leads to the formation of the hexacoordinate complexes [(NN 3)U(CCPh)2(Li 3 THF)] (1) and [(NN 3) 2U2(p-DEB)(THF)] (2) as red-brown and yellow-green crystalline solids, respectively. In contrast, combining the uranacycle [(bit-NN 3)U] (bit-NN3 = [N(CH2CH 2NSitBuMe2)2(CH2CH2SitBuMeCH 2]) with stoichiometric amounts of mono-, bis-, and tris(ethynyl) benzenes affords the yellow-green pentacoordinate arylacetylide complexes [(NN3)U(CCPh)] (3), [(NN3)2U 2-(m-DEB)] (4), [(NN3)2U2(p-DEB)] (5), and [(NN3)3U3(TEB)] (6), where NN 3 = [N(CH2CH2NSitBuMe2)3]. The measured magnetic susceptibilities for 1-6 trend toward non-magnetic ground states at low temperatures. Nevertheless, the di-and trinuclear pentacoordinate compounds 4-6 appear to display weak magnetic communication between the uranium centers. This communication is modeled by fitting of the direct current (DC) magnetic susceptibility data, using the spin Hamiltonian H =-2J(S iSi* S j). These results are consistent with weak ferromagnetic coupling for complexes 4-6 (J = 4.76, 2.75, and 1.11 cm -1, respectively), while the fit for 2 is consistent with a near-negligible exchange interaction (J =-0.05 cm-1). Geometry-optimized Stuttgart/6-31 g* B3LYP hybrid DFT calculations were carried out (spin-orbit coupling omitted) on model complexes of 3-5. The mononuclear complex shows a triplet ground state with singly occupied degenerate f orbitals. The meta-and para-bridged species are computed to show very weak ferro-and antiferromagnetic coupling, respectively. All three complexs show only small net spin density on the acetylide-containing ligands. The monomeric phenylacetylide complex 3 undergoes a reversible redox couple at-1.02 V versus [Cp2Fe]+/0, assignable to an oxidation of U(IV) to U(V).
Synthesis of a highly strained uranacycle: Molecular structures of organometallic products arising from reduction, oxidation and protonolysis
Boaretto, Rita,Roussel, Paul,Alcock, Nathaniel W.,Kingsley, Andrew J.,Munslow, Ian J.,Sanders, Christopher J.,Scott, Peter
, p. 174 - 184 (2007/10/03)
The reaction of [U(NN′3)I] [NN′3=N(CH2CH2NSiMe2Bu t)3] with Group 1 and 2 metal alkyls gives, via metalation of a methylsilyl group, a highly strained metallacycle [U(bit-NN′sub
