A new macrocyclic ligand with a pendant naphthalene group, N-[2-(1-naphthyl)ethyl]-1-aza-4,8-dithiacyclodecane (L), has been synthesized and characterized. The copper(I)-acetonitrile complex [LCu(CH(3)CN)](PF(6)) (1) was synthesized from L and [Cu(CH(3)CN)(4)](PF(6)). The acetonitrile ligand from 1 was easily removed to give [LCu](PF(6)) (2). Complexes 1 and 2 have been crystallographically characterized. 1: C(21)H(28)N(2)CuF(6)PS(2), triclinic, P&onemacr;, a = 11.1901(10) Å, b = 11.2735(12) Å, c = 12.1350(10) Å, alpha = 98.996(8) degrees, beta = 117.188(6) degrees, gamma = 105.354(7) degrees, Z = 2, R1 = 0.0505 (wR2 = 0.1418). 2.0.5hexane: C(22)H(31)NCuF(6)PS(2), monoclinic, P2(1)/c, a = 15.7318(15) Å, b = 8.9164(10) Å, c = 17.205(5) Å, beta = 102.431(6) degrees, Z = 4, R1 = 0.0587 (wR2 = 0.1545). In addition, a cocrystallized mixture of both complexes was crystallographically characterized. 1&2.hexane: C(46)H(61)N(3)Cu(2)F(12)P(2)S(4), triclinic, P&onemacr;, a = 10.8308(9) Å, b = 12.6320(8) Å, c = 19.9412(13) Å, alpha = 80.445(5) degrees, beta = 76.405(6) degrees, gamma = 78.825(5) degrees, Z = 2, R1 = 0.0661 (wR2 = 0.1871). The solid-state structure of 2 features the pendant naphthalene group bound in an eta(2)-fashion, which is highly unusual for copper complexes. In CDCl(3), 2 exhibits fluxional behavior with the barrier to the process estimated, DeltaG() = 12-13 kcal. Variable temperature NMR spectroscopy gave compelling evidence for solution binding of the naphthalene group in 2, apparently the first example for copper(I). The fluxional process seen for 1 is best described as interconversion of the two enantiomers via a species with an unbound naphthalene group. Consistent with the weak binding of the naphthalene group, it is readily replaced with other ligands, such as triphenylphosphine to form [LCu(PPh(3))](PF(6)) (3). Complex 3 has also been structurally characterized: C(37)H(40)NCuF(6)P(2)S(2), monoclinic, P2(1)/c, a = 11.462(2) Å, b = 15.972(2) Å, c = 19.835(9) Å, beta = 94.50(3) degrees, Z = 4, R1 = 0.0906 (wR2 = 0.1889).

Variable-temperature one- and two-dimensional NMR experiments with [LCu](PF6) (L = N-(2-(1-naphthyl)ethyl)-1-aza-4,8-dithiacyclodecane) reveal solution binding of the pendant naphthalene group, consistent with the η2 binding found in the solid-state structure. The free energy for the barrier to the process that involves coordination/decoordination of the naphthalene group was estimated to be 12−13 kcal/mol.

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The syntheses of two new ligands containing macrocyclic [10]-aneNS 2 (1-aza-4,8-dithiacyclodecane) units are reported, including the N-methylated analogue (L Me ) and a dinucleating version that separates two [10]-aneNS 2 groups with a m-xylyl spacer (L 2 ). Copper complexes with these new ligands as well as previously reported related complexes have been found to mediate the aziridination of olefins. Thus, isolated copper complexes containing the ethylnaphthyl-appended [10]-aneNS 2 macrocyclic ligand (L nap ), including [L nap Cu]PF 6 (1) and [L nap Cu(CH 3 CN)]PF 6 (2), the Cu(I) complex [L Me Cu(CH 3 CN)]PF 6 (3), and the Cu(II) complex L Me CuBr 2 (4), were compared in their ability to function as aziridination precatalysts. In addition, the aziridination capabilities were probed for complexes generated in situ from copper(I) ion sources and L 2 , 1,4,7-triazacyclononane, 1,4,7-trithiacyclononane, or 1,4,7trimethyl-1,4,7-triazacyclononane. The synthesis and characterization of the new complexes 3 and 4 are reported, including X-ray crystal structures. The aziridination reaction using precatalyst 3 was examined for its tolerance to different functional groups near the olefin as well as to the use of other nitrogen group sources and reaction conditions.