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Improved synthesis of (η5-CpR)M(CO)4 compounds and the Nujol matrix photochemistry of (η5-C5H5)M(CO)4 and (η5-C9H7)M(CO)4, where M=Nb and Ta

1998; Elsevier BV; Volume: 557; Issue: 1 Linguagem: Inglês

10.1016/s0022-328x(97)00735-3

1872-8561

Thomas E. Bitterwolf, Skip Gallagher, J. Timothy Bays, Bruce Scallorn, Arnold L. Rheingold, Ilia A. Guzei, Louise M. Liable‐Sands, John C. Linehan,

Fluorine in Organic Chemistry

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, Pı̄, 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.