Synthesis and Structural Characterization of 2,6-Dimesitylphenyl Complexes of Scandium, Ytterbium, and Yttrium

The molecular structures of a number of 2,6-dimesitylphenyl-based (2,6-dimesitylphenyl = Dmp) complexes of the
group 3 elements scandium and yttrium as well as of the lanthanide element ytterbium are reported. Reaction of
1 equiv of DmpLi with 1 equiv of MCl3 (M = Sc, Yb, Y) in tetrahydrofuran at room temperature followed by
crystallization from toluene/hexanes at −30 °C produces DmpMCl2(THF)2 (M = Sc:  1; M = Yb:  2) and DmpMCl2(THF)3 (M = Y:  3), respectively. The one-pot reaction of DmpLi with 1 equiv of YbCl3 in tetrahydrofuran at room
temperature followed by addition of 1 equiv of KOtBu produces the heterobimetallic monoalkoxide complex DmpYb(THF)(OtBu)(μ-Cl)2Li(THF)2 (4), which was crystallized from toluene/tetrahydrofuran (20:1) at −30 °C. Crystal data
for 1:  monoclinic, P21/n; T = 203 K; a = 10.178(3) Å; b = 15.468(3) Å; c = 20.132(5) Å; β = 101.85(3)°; V =
3102.0(17) Å3; Z‘ = 4; Dcalcd = 1.228 g cm-3; R1 = 5.89%. Crystal data for 2:  monoclinic, P21/n; T = 173 K; a
= 10.2447(7) Å; b = 15.5683(12) Å; c = 20.0979(14) Å; β = 101.749(4)°; V = 3238.3(5) Å3; Z‘ = 4; Dcalcd =
1.485 g cm-3; R1 = 4.32%. Crystal data for 3:  monoclinic, P21/n; T = 203 K; a = 15.950(3) Å; b = 11.865(2)
Å; c = 18.254(3) Å; β = 92.323(3)°; V = 3451.9(10) Å3; Z‘ = 4; Dcalcd = 1.327 g cm-3; R1 = 4.43%. Crystal data
for 4:  triclinic, P1̄; T = 193 K; a = 10.2252(2) Å; b = 11.3497(2) Å; c = 18.5814(2) Å; α = 98.7353(6)°; β =
102.8964(6)°; γ = 94.8058(5)°; V = 2062.09(5) Å3; Z‘ = 2; Dcalcd = 1.375 g cm-3; R1 = 4.56%. The molecular
structures of 1−3 feature monomeric complexes with distorted trigonal-bipyramidal (1 and 2) or octahedral (3)
coordination geometry about the metal atom, with the two chlorine atoms occupying the axial positions. 4 represents
the first example of an alkoxide derivative of a terphenyl lanthanide complex. The molecular structure of the ate
complex 4 exhibits a heavily distorted trigonal-bipyramidal coordination polyhedron about the ytterbium atom, with
one of the μ-chlorine atoms and the oxygen atom of the tetrahydrofuran ligand representing the axial positions of
the trigonal-bipyramidal arrangement. A terminal alkoxide ligand is another main feature of the molecular structure
of complex 4.