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• 931-53-3 Cyclohexyl isocyanide 

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Electon-structured high-symmetry bonding of f-element. Part 33. First-time experimentalcrystal field analysis of a trigonal bipyramidal coordination lanthanide(III) system: Pr[N(SiMe3)2]3(CNR)2 (R = tBu, C6H11)

The absorption und magnetic circular dichroism spectra of the dissolved trigonal-bipyramidal complex Pr[N(SiMe3)2]3(CNtBu) 2 (1) as well as the luminescence and absorption spectra of both solid 1 and solid Pr[N(SiMe3)2]3(CNC6 H11)2 (2) (pellets, unoriented single crystals were measured at ambient and low temperatures. Because of the violation of the selection rules for D3h symmetry by both compunds a reliable crystal field (CF) splitting pattern for the ground manifold 3H4, but only a plausible for the f2 configuration could be derived on the basis of these measurements. The latter could be simulated with a reduced r.m.s. deviation of 32.6 cm-1 for 29 assignments by fitting the free parameters of a phenomenological Hamiltonian. The adequacy of the calculated wavefunctions of this fit in the low energy range is proved by the excellent agreement of calculated and experimental temperature dependence of μeff2 for compund 1. The CF parameters of this fit are considered as a master set of CF parameters for future CF analyses of the electronic structures of trigonal bipyramidally coordinated lanthanide(III) systems.

Electronic structures of highly symmetrical compounds of f elements. 34 [1] Synthesis and spectroscopic characterization of biscyclohexylisocyanide adducts derived from the tris(bis(trimethylsilyl)amido)lanthanide(III) moiety as well as crystal, molecular, and electronic structure of the corresponding neodymium compound

The reaction of tris(bis(trimethylsilyl)amido)lanthanide(III) (Ln(btmsa)3) with two equiv. of cyclohexylisocyanide gives good yields of complexes of composition Ln(btmsa)3(CNC6H11)2 (Ln = Y(1), La(2), Ce(3), Pr(4), Nd(5), Sm(6), Eu(7), Tb(8), Dy(9), Ho(10), Tm(11) and Yb(12)). Complex 5 crystallizes in the monoclinic space grouop C2/c with a = 25.689(8) A, b = 12.165(2) A, c = 17.895(15) A, β = 122.47 (2)°, V = 4718.07 A3, Z = 4 and R = 0.0342. The structure of compound 5 shows the five-coordinate Nd3+ ion in a nearly exact trigonal bipyramidal environment with two CNC6H11 molecules in the axial and the three btmsa ligands in the equatorial positions. The linear dichroism spectrum of a single crystal of complex 5 was measured at room temperature, and the absorption spectrum of powdered material at low temperatures. From the spectra obtained a truncated crystal field (CF) splitting pattern is derived, and simulated by fitting the parameters of a phenomenological Hamiltonian. For 80 assignments a reduced r.m.s, deviation of 20.7 cm-1 is achieved. Making use of the calculated wavefunctions and eigenvalues the experimentally determined temperature dependence of μ2eff could be reproduced by adopting an orbital reduction factor k = 0.991, and on the basis of the CF parameters used the experimentally oriented non-relativistic molecular orbital scheme of compound 5 is set up.