Direct lanthanide-transition metal interactions: Synthesis of (NH3)(2)YbFe(CO)(4) and crystal structures of {[(CH3CN)(3)YbFe(CO)(4)](2)center dot CH3CN}(infinity) and [(CH3CN)(3)YbFe(CO)(4)](infinity)

The heterometallic complex (NH3)(2)YbFe(CO)(4) was prepared from the reduction of Fe-3(CO)(12) by Yb in liquid ammonia. Ammonia was displaced from (NH3)(2)YbFe(CO)(4) by acetonitrile in acetonitrile solution, and the crystalline compounds {[(CH3CN)(3)YbFe(CO)(4))](2) . CH3CN}(infinity) and [(CH3CN)(3)YbFe(CO)(4)](infinity) were obtained. An earlier X-ray study of {[(CH3CN)(3)YbFe(CO)(4)](2) . CH3CN}(infinity) showed that it is a ladder polymer with direct Yb-Fe bonds. In the present study, an X-ray crystal structure analysis also showed that [(CH3CN)(3)YbFe(CO)(4)](infinity) is a sheetlike array with direct Yb-Fe bonds. Crystal data for {[(CH3CN)(3)YbFe(CO)(4)](2) . CH3CN}(infinity); monoclinic space group P2(1)/c, a = 21.515(8) Angstrom, b = 7.838(2) Angstrom, c = 19.866(6) Angstrom, beta = 105.47(2)degrees, Z = 4. Crystal data for [(CH3CN)(3)YbFe(CO)(4)](infinity): monoclinic space group P2(1)/n, a = 8.364(3) Angstrom, b = 9.605(5) Angstrom, c = 17.240(6) Angstrom, beta = 92.22(3)degrees, Z = 4. Electrical conductivity measurements in acetonitrile show that these acetonitrile complexes are partially dissociated into ionic species. IR and NMR spectra of the solutions reveal the presence of [HFe(CO)(4)](-). However, upon recrystallization, the acetonitrile complexes show no evidence for the presence of [HFe(CO)(4)](-) the basis of their IR spectra. The solid state MAS H-2 NMR spectra of deuterated acetonitrile complexes give no evidence for [(HFe)-H-2(CO)(4)](-). It appears that rupture of the Yb-Fe bond could occur in solution to generate the ion pair [L(n)Yb](2+)[Fe(CO)(4)](2-), but then the highly basic [Fe(CO)(4)](2-) anion could abstract a proton from a coordinated acetonitrile ligand to form [HFe(CO)(4)](-). However, upon crystallization, the proton could be transferred back to the ligand, which results in the neutral polymeric species.