LANTHANIDE AND YTTRIUM COMPLEXES OF DEPROTONATED 4,13-DIAZA-18-CROWN-6 (DAC) - SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF Y[DAC][N(SIME(3))(2)] AND THE NOVEL TRINUCLEAR YTTERBIUM(II) COMPLEX (YB[N(SIME(3))(2)][MU-DAC])2YB
L. Lee et al., LANTHANIDE AND YTTRIUM COMPLEXES OF DEPROTONATED 4,13-DIAZA-18-CROWN-6 (DAC) - SYNTHESIS AND STRUCTURAL CHARACTERIZATION OF Y[DAC][N(SIME(3))(2)] AND THE NOVEL TRINUCLEAR YTTERBIUM(II) COMPLEX (YB[N(SIME(3))(2)][MU-DAC])2YB, Inorganic chemistry, 33(23), 1994, pp. 5302-5308
The ability of a deprotonated diazacrown ether, 4,13-diaza-18-crown-6
(DAC), to allow isolation of soluble lanthanide and yttrium complexes
was investigated. Reaction of H(2)DAC with Ln[N(SiMe(3))(2)](3) provid
ed soluble complexes, Ln[DAC][N(SiMe(3))(2)] (Ln = Y (1a), Ce (1b)). A
single crystal X-ray diffraction study of 1a revealed a seven-coordin
ate monomer in which the six donors of the DAC Ligand adopt a basketli
ke conformation around the yttrium atom. [Crystal data: monoclinic spa
ce group P2(l)/n, a = 9.471(1) Angstrom, b = 28.786(3) Angstrom, c = 1
0.567(3) Angstrom, beta = 114.45(1)degrees, V = 2622.5 Angstrom(3), Z
= 4, R = 0.010, R(w) = 0.124.] Reaction of H(2)DAC with divalent Yb-[N
(SiMe(3))(2)](2)[OEt(2)](2) in 2:3 stoichiometry provided the novel tr
inuclear cluster {[(Me(3)Si)(2)N]Yb(mu-DAC)}Yb-2 (2). The crystal stru
cture of 2 shows a linear (Me(3)Si)N-Yb-Yb-Yb-N(SiMe(3))(2) arrangemen
t with two DAC amido-N groups bridging between pairs of adjacent Yb ce
nters. The DAC ligand is folded back such that the four ether donors i
nteract with an outer Yb atom (seven-coordinate). The central four-coo
rdinate Yb exhibits distorted tetrahedral coordination. [Crystal data:
monoclinic space group P2(l)/n, a = 19.982(3) Angstrom, b = 17.870(2)
Angstrom, c = 16.933(3) Angstrom, beta = 113.56(1)degrees, V = 5542 A
ngstrom(3), Z = 4, R = 0.087, R(w) = 0.104.] Reaction of H(2)DAC with
Yb-[N(SiMe(3))(2)](2)[OEt(2)](2) in 1:2 stoichiometry produced the din
uclear complex {Yb[N(SiMe(3))(2)]}(2)(mu-DAC} (3). Divalent Sm[N(SiMe(
3))(2)](2)[THF](2) reacts with H(2)DAC to yield trivalent Sm[DAC][N(Si
Me(3))(2)] (4) in good yield. Experimental evidence suggests that this
product if formed by the unusual Sm(II) reduction of a DAC N-H bond.