Uranium–hydrogen interactions: synthesis and crystal structures of tris(N,N-dimethylaminodiboranato)uranium(iii)

Abstract

The reaction of UCl(4) with Na(H(3)BNMe(2)BH(3)) in diethyl ether affords the uranium(III) product U(H(3)BNMe(2)BH(3))(3), which has been crystallized in two different structural isomers depending on the crystallization solvent. Both forms are polymeric, but the nature of the bridging interaction is different in the two forms.

Synthesis and Properties of a Fifteen‐Coordinate Complex: The Thorium Aminodiboranate [Th(H3BNMe2BH3)4]

“…Some derivatives of these compounds also have high coordination numbers, such as the 14-coordinate tetrahydrofuran complex [U(BH 4 ) 4 (thf) 2 ]. This compound extends our recent studies of a new class of chelating borohydride ligands, that is, the aminodiboranates, [23][24][25][26] some of which form highly volatile complexes that are useful as precursors for the chemical vapor deposition of thin films. [16,22] Herein, we report the synthesis, single-crystal X-ray and neutron diffraction studies, and DFT investigations of the first 15-coordinate complex.…”

“…DFT calculations suggest that this complex may adopt a 16-coordinate structure in the gas phase. This compound extends our recent studies of a new class of chelating borohydride ligands, that is, the aminodiboranates, [23][24][25][26] some of which form highly volatile complexes that are useful as precursors for the chemical vapor deposition of thin films. [25,26] Reaction of ThCl 4 with four equivalents of sodium N,Ndimethylaminodiboranate, Na(H 3 BNMe 2 BH 3 ), in tetrahydrofuran produced [Th(H 3 BNMe 2 BH 3 ) 4 ] (1), which could be isolated as colorless prisms by crystallization from diethyl ether.…”

“…The Th-H distances calculated from the neutron diffraction study range from 2.37(2) to 2.539 (18) , which are longer than the bridging thorium hydride distance calculated from the neutron diffraction study of [(Cp* 2 ThH) 2 (m-H)] (Th-H = 2.29(3) ; Cp* = pentamethylcyclopentadienyl), [27] and those observed from the single-crystal XRD study of [Cp* 3 ThH] and the m 2 -bridging hydrides in [Th 3 (m 3 -H) 2 (m 2 -H) 4 (O-2,6-tBu 2 C 6 H 3 ) 6 ] at 2.33(13) and 2.0(1)-2.3(1) , respectively. [24] In one of the two forms, some of the aminodiboranate ligands bridge between metal centers in a [U(k 3 -H 3 BNMe 2 BH 3 -k 3 )U] fashion. [29] Although the aminodiboranate ligands in 1 are chelating ligands, the coordination mode of 1 is not the only mode possible for this anion.…”

“…For example, the analogous reaction of UCl 4 with Na(H 3 BNMe 2 BH 3 ) results in reduction to form the related U III compound [U(H 3 BNMe 2 BH 3 ) 3 ], which crystallizes in two different forms. [24] In one of the two forms, some of the aminodiboranate ligands bridge between metal centers in a [U(k 3 -H 3 BNMe 2 BH 3 -k 3 )U] fashion. We have also seen bridging modes in aminodiboranate compounds of the lanthanides.…”

Synthesis and Properties of a Fifteen‐Coordinate Complex: The Thorium Aminodiboranate [Th(H3BNMe2BH3)4]

“…Although the aminodiboranate ligands in 1 are chelating ligands, the coordination mode of 1 is not the only mode possible for this anion. For example, the analogous reaction of UCl 4 with Na(H 3 BNMe 2 BH 3 ) results in reduction to form the related U III compound [U(H 3 BNMe 2 BH 3 ) 3 ], which crystallizes in two different forms 24. In one of the two forms, some of the aminodiboranate ligands bridge between metal centers in a [U(κ 3 ‐H 3 BNMe 2 BH 3 ‐κ 3 )U] fashion.…”