Donor/acceptor complexes containing ferrocenyl-pyridine ligands attached to a tungsten carbonyl centre: Structural, spectroscopic and electrochemical properties

Article abstract of DOI:10.1016/S0022-328X(96)06395-4

A series of ferrocenyl-pyridine ligands (Fc-L) in which a 4-pyridyl side-arm is attached to a ferrocenyl core via a conjugated linker has been attached to tungsten carbonyl cores, giving complexes of the type [(Fc-L)W(CO)₅] (1-6) and [(Fc-L)₂W(CO)₄] (7 and 8). Three of these complexes were characterised by X-ray crystallography. Complex 2, [{Fc-C(Ph)=CH-C₅H₄N}W(CO)₅]: triclinic, P1; a = 9.329(4), b= 12.115(3), c= 12.745(3) A; α = 66.66(2), β = 71.87(2), γ = 81.40(2)°; Z = 2; 3230 unique data; R₁=0.032, wR₂ = 0.090. Complex 3, [{Fc-C(Me)=CH-C₅H₄N}W(CO)₅]: triclinic, P1; a= 11.325(3), b= 12.328(2), c= 16.639(5) A; α = 79.83(2), β = 77.30(2), γ = 82.043(14)°; Z = 4; 5878 unique data; R₁ = 0.035. wR₂ = 0.103. Complex 7 · (CH₂Cl₂)_0.5, [{Fc-CH = CH-C₅H₄N}₂W(CO)₄ · (CH₂Cl₂)_0.5]: triclinic, P1; a= 10.290(2), b = 11.751(4), c = 16.328(4) A; α = 88.071(14), β = 83.502(14), γ = 67.50(2)°; Z = 2; 5054 unique data; R₁ = 0.047, wR₂ = 0.125. All of the complexes were fully characterised by ¹H and ¹³C NMR, IR, UV-vis and luminescence spectroscopy, FAB mass spectrometry, and electrochemical measurements. The complexes show the expected spectroscopic and electrochemical features for both the ferrocenyl and substituted tungsten carbonyl chromophores. Although the individual molecules possess the necessary structural and electronic features required for second-order non-linear optical behaviour, the fact that the three crystallographically characterised complexes have centrosymmetric space groups precludes bulk solid-state measurements of NLO behaviour.