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

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 cares, giving complexes of the type [(Fc-L)W(CO)(5)] (1-6) and [(Fc-L)(2)W(CO)(4)] (7 and 8). Three of these complexes were characterised by X-ray crystallography. Complex 2, [{Fc-C(Ph) = CH-CH5H5N}W(CO)(5)]: triclinic, <P(1)over bar>; a = 9.329(4), b = 12.115(3), c = 12.745(3) Angstrom; alpha = 66.66(2), beta = 71.87(2), gamma = 81.40(2)degrees; Z = 2; 3230 unique data; R(1) = 0.032, wR(2) = 0.090. Complex 3, [{Fc-C(Me) = CH-C5H4N)W(CO)(5)]: triclinic, <P(1)over bar>; a = 11.325(3), b = 12.328(2), c = 16.639(5) Angstrom; alpha = 79.83(2), beta = 77.30(2), gamma = 82.043(14)degrees; Z = 4; 5878 unique data; R(1) = 0.035, wR(2) = 0.103. Complex 7 . (CH2Cl2)(0.5), [{Fc-CH = CH-C5H4N)(2)W(CO)(4) . (C5H4N)(2)W(CO)(4) .(CH2Cl2)(0.5)]: triclinic, <P(1)over bar>; a = 10.290(2), b = 11.751(4), c = 16.328(4) Angstrom; alpha = 88.071(14), beta = 83.502(14), gamma = 67.50(2)degrees; Z = 2; 5054 unique data; R(1) = 0.047, wR(2) = 0.125. All of the complexes were fully characterised by H-1 and C-13 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.