Improved preparative routes for cyclopentadienyl (Cp) and substituted Cp(CO)4 derivatives of niobium and tantalum and their precursors are described. New compounds are fully characterized by IR, NMR, and elemental analysis. The molecular structures of five compounds were determined: (vinylCp)Nb(CO)4: triclinic, Pī, a=6.770(1) Å, b=6.937(1) Å, c=12.706(2) Å, α=90.42(1)°, β=91.07(1)°, γ=105.560(8)°, V=574.71(12) Å3, Z=2, R(F)=2.82; (acetylCp)Nb(CO)4: monoclinic, P21/c, a=10.316(2) Å, b=14.490(3) Å, c=7.957(3) Å, β=94.68(2)°, V=1185.4(4) Å3, Z=4, R(F)=2.58; (Cp)Ta(CO)4: orthorhombic, Pnma, a=7.756(1) Å, b=12.159(2) Å, c=10.580(1) Å, V=997.7(2) Å3, Z=4, R(F)=2.60; (indenyl)Ta(CO)4: monoclinic, P21/n, a=6.602(2) Å, b=12.399(1) Å, c=7.4775(9) Å, β=92.05(2)°, V=611.2(2) Å3, Z=2, R(F)=3.05; and (benzoylCp)Ta(CO)4: monoclinic, P21/c, a=12.552(10) Å, b=6.5247(2) Å, c=18.4682(2) Å, β=98.9152(4)°, V=1494.24(5) Å3, Z=4, RF)=2.83 are reported. Photolysis of CpMCO)4 and indenyl)MCO)4, where M=Nb and Ta, in Nujol glass matrices were found to result in loss of one to three CO ligands as a function of the wavelength of the incident light. Annealing or reverse photolysis resulted in reversal of these CO-loss reactions.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Organic Chemistry
- Inorganic Chemistry
- Materials Chemistry