Copper(II) complexes of mono- and di-nucleating hexaamines †

Diverse Solid-State and Solution Structures within a Series of Hexaamine Dicopper(II) Complexes

“…The solution spectroscopic properties of the monometallic [Cu(HL 3 )] 3+ ion are unique among all other complexes reported in this work. The visible electronic maxima for this complex (ε ∼ 850 nm ≈ 190 M -1 cm -1 (shoulder), ε 732 nm = 210 M -1 cm -1 , and ε ∼ 650 nm ≈ 170 M -1 cm -1 (shoulder)) are very similar to those reported for the distorted trigonal bipyramidal relative [Cu(HL 1 )] 3+ , and an assignment of these transitions has been given elsewhere . The frozen solution EPR spectra of [Cu(HL 3 )] 3+ and [Cu(HL 1 )] 3+ are also indistinguishable and again consistent with distorted trigonal bipyramidal monometallic Cu II complexes; g x = 2.264 ( A x = 131 G), g y = 2.140 ( A y = 25 G), g z = 2.025 ( A z = 25 G).…”

“…The Cu−Cu separations within the centrosymmetric Cu 4 rectangular array are 5.091(1) Å (across the bridging carbonate), 7.912(1) Å (across the C-3 bridge), 9.313(2) Å (diagonal Cu1···Cu1 # ), and 9.502(2) Å (diagonal Cu2···Cu2 # ). The observation that N-methylation of the primary amines of this class leads to 2:1 metal/ligand complexes was first demonstrated for the mono- and bimetallic complexes of the ligands L 1 and L 2 , respectively . In this case, a similar result is obtained where the steric bulk of the dimethylamino arms disfavors a 1:1 metal/ligand complex, which would require the simultaneous coordination of five or six tertiary amines to the one metal center.…”

“…7 Recently, a pyridyl-appended macrocyclic ether has also been reported, which forms a dicopper complex with O 2 -binding activity. 8 Recently we reported 9 the syntheses, crystal structures, and spectroscopic properties of the Cu II complexes of the branched hexaamines L 1 and L 2 . We found that the EDTA analogue L 1 binds as a pentadentate to give a trigonal bipyramidal monometallic Cu II complex with one free aminoethyl "arm".…”

Template Synthesis of Copper(II) Complexes of N3O-Donor Macrotricycles Containing N-CH2-N and N-CH2-O Linkages

“…[18][19][20][21] It has been also observed that regular and distorted square-pyramidal copper(II) complexes exhibit a d-d transition band in the region 550-670 nm, whereas trigonal bipyramidal ones show a maximum absorption at > 670 nm. 18,19,[21][22][23] Unfortunately, we could not obtain single crystals of the copper(II) complexes suitable for X-ray work, and their crystal structures have not been investigated. However, the longer wavelengths and the larger molar absorption coefficients for [CuL (Table 2) …”

The Stability of MetalN,N,N′,N′-Tetrakis(2-aminoethyl)ethane- 1,2-diamine (=penten) Complexes and the X-Ray Crystal Structure of [Tl(NO3)(penten)](NO3)2

“…2). Quite recently, it was shown that, in the solid state, [Cu(penten)] 2 has a coordination number of five with a trigonal bipyramidal structure [18].…”