Bm. Rapko et al., Coordination of lanthanide triflates and perchlorates with N,N,N ',N '-tetramethylsuccinamide, INORG CHEM, 39(21), 2000, pp. 4858-4867
Compounds formed from the reaction of N,N,N,N-tetramethylsuccinamide (TMSA)
with trivalent lanthanide salts possessing the poorly coordinating counter
anions triflate (CF3SO3-) and perchlorate (ClO4-) have been prepared and ex
amined. Structural features of these Ln-TMSA compounds have been studied in
the solid phase by thermogravimetric analysis, infrared spectroscopy, and,
in selected cases, by single-crystal X-ray diffraction and in solution by
infrared spectroscopy. Eight-coordinate compounds, [Ln(TMSA)(4)](3+), deriv
ed from coordination of four succinamide ligands to the metal ion could be
formed with all lanthanides examined (Ln = La,Pr,Nd, Eu, Yb, Lu). Structura
l analyses by single-crystal X-ray diffraction were performed for the lanth
anide triflate salts Ln(C8H16N2O2)(4)(CF3SO3)(3): Ln = La, compound 1, mono
clinic, P2(1)/n, a = 11.0952623 Angstrom, b = 19.2672(2) Angstrom, c = 24.9
759(3) Angstrom, beta = 90.637(1)degrees Z = 4, D-calcd = 1.586 g cm(-3); L
n = Nd, compound 2, monoclinic, C2/c, a = 24.6586(10) Angstrom, b = 19.3078
(7) Angstrom, c = 11.1429(4) Angstrom, beta = 90.450(1)degrees, Z = 4, D-ca
lcd = 1.603 g cm(-3); Ln = Eu, compound 3, monoclinic, C2/c, a = 24.4934(2)
Angstrom, b = 119.3702(1) Angstrom, c = 11.1542(1) Angstrom, beta = 90.229
(1)degrees Z = 4, D-calcd = 1.617 g cm(-3); Ln = Lu, compound 5, monoclinic
, C2/c, a = 24.2435(4) Angstrom, b = 19.6141(2) Angstrom, c ;= 11.2635(1) A
ngstrom, beta = 90.049(1)degrees Z = 4, D-calcd = 1.626 g cm(-3). X-ray ana
lysis was also carried out for the perchlorate salt: Ln = Eu, compound 4, t
riclinic, P1, a = 10.9611(2) Angstrom. b = 14.6144(3) Angstrom, c = 15.7992
(2) Angstrom, a = 106.594(1)degrees, beta = 91.538(1)degrees gamma = 90.311
(1)degrees Z = 2, D-calcd = 1.561 g cm(-3). In the presence of significant
amounts of water, 7-coordinate compounds with mixed aquo-TMSA cation struct
ures [Ln(TMSA)(3)(H2O)(3+) (Ln = Yb)] and [Ln(TMSA)(2)(H2O)(3)](3+) (Ln = L
a, Pr, Nd, Eu, Yb) have been isolated with structural determinations by sin
gle-crystal X-ray diffraction obtained for the following species: Yb(C8H16N
2O2)(3)(H2O)(CF3SO3)(3), compound 6, monoclinic, P2(1)/n, a = 8.9443(3) Ang
strom, b = 11.1924(4) Angstrom, c = 44.2511(13) Angstrom, beta = 93.264(1)d
egrees, Z = 4, D-calcd = 1.735 g cm(-3); Yb(C8H16N2O2)(3)(H2O)(ClO4)(3), co
mpound 7, monoclinic, Cc, a = 19.2312(6) Angstrom, b = 11.1552(3) Angstrom,
c = 19.8016(4) Angstrom, beta = 111.4260(1)degrees, Z = 4, D-calcd = 1.690
g cm(-3); Yb(C8H16N2O2)(2)(H2O)(3)(CF3SO3)(3), compound 8, triclinic, P1,
a = 8.6719(1) Angstrom, b = 12.2683(2) Angstrom, c = 19.8094(3) Angstrom, a
lpha = 75.815(1)degrees, beta = 86.805(1)degrees, gamma = 72.607(1)degrees
Z = 2, D-calcd = 1.736 g cm(-3). Unlike in the analogous nitrate salts, onl
y bidentate binding of the succinamide ligand to the lanthanide metal is ob
served. IR spectroscopy studies in anhydrous acetonitrile suggest that the
solid-state structures of these Ln-TMSA compounds are maintained in solutio
n.