Derivative chemistry of [UCl2{B(pz)4}2]: Stability of complexes containing the fragments [U{B(pz)4}2] and [U{HB(pz)3}2]

1999

Uranium tetrachloride reacts with two equivalents of K[B(pz)4] in THF affording [UCl2{B(pz)4}2] (1) in 75% yield. Complex 1 is monomeric and crystallizes in the monoclinic space group C2:c with cell parameters a= 13.700(6), b = 12.759(2), c=17.513(8) A° ;B= 101.37(2)°, V= 3001(2) A°3, Z=4. Derivatives [UCl(OR){B(pz)4}2] (RC2H5 (2), tBu (3), C6H4-o-OMe (4) and C6H2-2,4,6-Me3 (5)), [U(OtBu)2{B(pz)4}2] (6), [U(SiPr)2{B(pz)4}2] (7) and [UCl(Me){B(pz)4}2] (8) were obtained by reacting 1 with sodium alkoxides, with NaSiPr or with LiMe. X-ray crystallographic analysis of 5 and 7 shows that uranium is eight-coordinate by the two h3-[B(pz)4] ligands and by two monodentate coligands (5: crystallizes in the monoclinic space group C2:c with cell parameters a=30.575(3), b=9.929(1), c=24.884(3) A°, b=90.59(1)°, V=7554(1) A°3, Z=8; 7 crystallizes in the monoclinic space group C2:c with cell parameters a=24.286(7), b=9.471(2), c=16.076(3) A° , b=96.44(3)°, V=3674(2) A° 3, Z=4). Extended Huckel molecular orbital (EHMO) calculations were used to get a better insight into the electronic properties of the ligand [B(pz)4] and to get some explanation on the relative stability of complexes containing the fragments ‘[U{B(pz)4}2]’ and ‘[U{HB(pz)3}2]’.

Autores da comunidade :

• 

  A

  Adelino Leitão de Moura Galvão

  ist13175

  Afiliações e fontes

  IST > CQE

  Centro de Química Estrutural

  IST > DEQ

  Departamento de Engenharia Química

• 

  I

  Isabel da Graça Rego dos Santos

  ist25348

• 

  M

  Maria Paula Cordeiro Crespo Cabral Campello Aboim de Barros

  ist25375

  Afiliações e fontes

  De: cienciavitae

  ID: 616728

AO - Versão original do autor

Elsevier

Journal of Organometallic Chemistry

5

17

579

1-2

10.1016/s0022-328x(98)01134-6

chemical-sciences - Química

Palavras-chave

• Uranium
• Poly(pyrazolyl)borates
• EHMO calculations
• Stability

eng - Inglês

http://www.scopus.com/inward/record.url?eid=2-s2.0-0346341189&partnerID=MN8TOARS