Copper(I) Complexes with a NS₂-Macrocyclic Ligand Bearing a Pendant Naphthyl Group:  Structures of {N-[2-(1-Naphthyl)ethyl]-1-aza-4,8-dithiacyclodecane}copper(I)−Ligand, where Ligand = η²-Naphthalene, Acetonitrile, or Triphenylphosphine

Abstract

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).

Tryptophan π‐Electron System Capping a Copper(I) Binding Site—A New Organometallic Bonding Mode in Proteins

“…The CuC bond lengths are almost equal (2.23 and 2.27 Å). B) Crystal structure of the η 2 ‐naphthyl‐1‐aza‐2,4,8‐dithiacyclodecane Cu I complex 31. Two thioether sulfurs and the tertiary amine nitrogen coordinate as common σ‐donor ligands to Cu I , and the tetrahedral sphere is completed by the π‐electron system of the naphthyl ring.…”

Metal–Arene Interactions in Dialkylbiarylphosphane Complexes of Copper, Silver, and Gold

“…[46] A few other arene-Cu I complexes have been structurally characterized and show unsymmetrical h 2 coordination (2.13-2.66 ). [47,48] It has been argued that the largest meaningful silverarene interaction should be less than 2.85 . [41] This value was based on an effective thickness of 3.4 for the aromatic plane (1.7 on each side) and an ionic radius of 1.15 for Ag I .…”

“…A few other arene–Cu I complexes have been structurally characterized and show unsymmetrical η 2 coordination (2.13–2.66 Å) 47. 48…”

A Copper(I)–Arene Complex With an Unsupported η6 Interaction

“…Received: November 11, 2014 Published online: January 21,2015 . Keywords: bonding analysis · copper · metal arenes · organometallic compounds · p complexes Table 2: Mulliken charges on the central Cu + ion for complexes 2 and 3 with a h 6 bound arene.…”

“…[16,17] Group 11 metal-arene complexes strongly prefer the h 2 binding mode. [12,[18][19][20][21][22][23] This binding mode is favored as it lessens the interaction between the filled nd orbitals with the filled arene p orbitals. [24] Consistent with this analysis, the only reported Cu arene complexes that contain the h 6 binding mode feature tethered arene rings and long Cu-C cent distances ( % 2.5-3.0 ) indicative of weak interactions (Figure 1).…”