Potentially Heptadentate Ligands Derived from Tris(2-aminoethyl)amine(tren)

Lanthanide complexes of potentially heptadentate Schiff base ligands

“…Solid-state spectra show a prominent shoulder centered near 23 000 cm-I which obscures observations of either d-d or f-f transitions in this region. Strong bands observed near 18000cm-' for the iron(1II) com- plexes of ligands I are probably also of chargetransfer (phenol -, iron(II1)) type (ll), but the weaker shoulder near 18000cm-' for the chromium(II1) complexes of I may be the expected ( I 1) vl transition for octahedral chromium(I1I) complexes since no shoulder to the 26000 cm-I band is found for the Sc (3,Saltren) and La (3,Saltren) complexes. Similarly, the weak band at 16400 cm-I observed in the solid state spectrum of Co (3,Saltren) M(5-ClSaltren) 3H20 (M = Cr, Mn, Fe) (5).…”

“…Strong bands observed near 18000cm-' for the iron(1II) com- plexes of ligands I are probably also of chargetransfer (phenol -, iron(II1)) type (ll), but the weaker shoulder near 18000cm-' for the chromium(II1) complexes of I may be the expected ( I 1) vl transition for octahedral chromium(I1I) complexes since no shoulder to the 26000 cm-I band is found for the Sc (3,Saltren) and La (3,Saltren) complexes. Similarly, the weak band at 16400 cm-I observed in the solid state spectrum of Co (3,Saltren) M(5-ClSaltren) 3H20 (M = Cr, Mn, Fe) (5). The absence of a shoulder to the intense 26000cm-' (E x 2 x lo3 mol-' L cm-I) band for dimethylsulfoxide solutions of the Ln(3,SSaltren) complexes doubtless implies an increase in coordination number upon dissolution, since the complexes are also insoluble in other common organic solvents.…”

“…Related complexes H,3,5-C1,Saltren 433bm, 375bs, 295bs, 130vs Cr Saltren) 476vs, 425111, 366m Fe (3,Saltren) 470b,sh, 450vs, 415111, 395m, 327b,s, 284m Sc (3,5-C1,Saltren) 462sh, 450vs, 440bvs, 413m, 395s, 343m, 327vs, 302s, 260s, 245111, 218s, 205m, 192wm, 134111 Y(3,5-C1,Saltren) 424s, 412m,380s, 343111, 306s, 280s, 220s, 167m since lanthanide metal isopropoxides and j3-diketonates also show strong bands in the same range (6,10). Of the bands at lower frequency, those near 270 cm-I and 200 cm-' appear to be likely candidates for the v(Ln-N) modes (6).…”

“…In the present work, we accordingly explore the ligating properties of potentially heptadentate Schiff base ligands (I) with several trivalent lanthanide metals. R = H , R' = H H3Saltren (Ia) R = H , R' = NO, H,5-N0,Saltren (Ib) R = H, R' = Cl H3S-ClSaltren (Ic) R = C1, R' = C1 H33,5-C1,Saltren (Id) Earlier work in our laboratory (3) described the synthesis of these trianionic ligands derived from tris(2-aminoethyl)amine(tren) and 3 mol of (substituted) salicylaldehydes and the characterization of M (3,Saltren) (M = Cr, Fe, La), where M33,5-C1,Saltren represents tris (3,5-dichlorosalicylidene-2-iminoethy1)amine (Id). The present trivalent metal complexes, prepared according to [l] are expected to have structures represented by the following:…”

Crystal Structure of a Gadolinium(III) Complex of Tripodal Tris(((5-chlorosalicylidene)amino)ethyl)amine

“…1 Heptadentate ligands, tris(((5-chlorosalicylidene)-amino)ethyl)amine (H3L) and tris(((salicylidene)amino)ethyl)-amine (H3L′), are condensation products of tren with 3 equivalents of salicylaldehyde or its 5-substituted derivative. We have reported lanthanide complexes of the tripodal heptadentate ligands, H3L and H3L′.…”