85848-65-3Relevant articles and documents
Axial-equatorial isomerism in the complexes M(CO)4(L) (M = Fe, Ru, Os; L = group 15 ligand). Crystal structures of ax-Ru(CO)4(AsPh3), ax-Ru(CO)4(SbMe3), and eq-Os(CO)4(SbPh3)
Martin, Lillian R.,Einstein, Frederick W. B.,Pomeroy, Roland K.
, p. 2777 - 2785 (2008/10/08)
The compounds M(CO)4(L) (M = Fe, Ru, Os; L = EPh3, E = P, As, Sb; L = PMe3, P(OCH2)3CMe. M = Ru, Os; L = SbMe3) have been synthesized from L and M(CO)5. The crystal structures of ax-Ru(CO)4(AsPh3), ax-Ru(CO)4(SbMe3), and eq-Os-(CO)4(SbPh3) have been determined by X-ray crystsllography. ax-Ru(CO)4(AsPh3): space group P1; a = 10.605 (3), b = 11.068 (4), c = 9.979 (3) ?; α = 113.57 (3), β = 93.14 (3), γ = 91.47 (3)°; Z = 2; R1 = 0.020, R2 = 0.021 (1650 observed reflections); AsPh3 in an axial position of the trigonal-bipyramidal coordination sphere, Ru-As = 2.461 (1) ?. ax-Ru(CO)4(SbMe3): space group R3, a = 10.378 (1), c = 9.632 (1) ?; Z =_3; R1 = 0.023, R2 = 0.030 (523 observed reflections); SbMe3 axial, Ru-Sb = 2.619 (1) ?. eq-Os(CO)4(SbPh3): space group P1; a = 11.123 (2), b = 11.284 (4), c = 12.714 (4) ?; α = 129.29 (2), β = 102.35 (2), γ = 102.45 (2)°; Z = 2; R1 = 0.019, R2 = 0.021 (3115 observed reflections); SbPh3 equatorial, Os-Sb = 2.612 (2) ?. Infrared spectroscopy revealed that in solution many of the complexes exhibited axial - equatorial isomerism. The tendency to give the less common equatorial isomer was Ru > Os > > Fe, Sb > As > P, Ph > Me, and P(OCH2)3CMe > PMe3, PPh3. The order for the group 15 element was rationalized in terms of the σ-donor ability of the element: in agreement with theoretical predictions, weaker donors prefer the equatorial site. The π-bonding ability of the ligands may also be important in determining the other trends. Carbon-13 NMR spectra, which revealed the isomers were in rapid equilibrium in solution, were also recorded.
