The synthesis and structures of rare earth 2-fluorophenyl- and 2,3,4,5-tetrafluorophenyl-N,N′-bis(aryl)formamidinate complexes

Article abstract of DOI:10.1016/j.poly.2015.10.016

Redox transmetallation/protolysis (RTP) reactions between free rare-earth metals (La, Nd, or Yb), Hg(C₆F₅)₂, and FFormH (FFormH = N,N′-bis(2-fluorophenyl)formamidine) in thf afforded four rare-earth complexes: trivalent [L

Full text of DOI:10.1016/j.poly.2015.10.016

Polyhedron 103 (2016) 178–186
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
The synthesis and structures of rare earth 2-fluorophenyl-
and 2,3,4,5-tetrafluorophenyl-N,N0-bis(aryl)formamidinate complexes q
b,
c
Glen B. Deacon a, , Peter C. Junk , Daniel Werner
⇑
⇑
a School of Chemistry, Monash University, Clayton, Victoria 3800, Australia
b College of Science, Technology & Engineering, James Cook University, Townsville, Queensland 4811, Australia
c Institute for Anorganische Chemie, Tuebingen University, Auf der Morgenstelle 18, 72076, Germany
a r t i c l e i n f o
a b s t r a c t
Article history:
Redox transmetallation/protolysis (RTP) reactions between free rare-earth metals (La, Nd, or Yb), Hg
(C6F5)2, and FFormH (FFormH = N,N0-bis(2-fluorophenyl)formamidine) in thf afforded four rare-earth
complexes: trivalent [La(FForm)3(thf)2]ꢀthf, [Nd(FForm)3(thf)x], [Yb(FForm)3(thf)] (when a slight excess
of Yb was used), and divalent [Yb(FForm)2(thf)2] (when a large excess of Yb was used). With the excep-
tion of [Yb(FForm)3(thf)], the complexes did not readily crystallise from thf. However, crystallisation from
either dme (La, Yb) or diglyme (Nd), produced single crystals of [La(FForm)3(dme)], [Yb(FForm)2(dme)2],
Received 22 September 2015
Accepted 9 October 2015
Available online 23 October 2015
Keywords:
Lanthanoids
Lanthanides
and [Nd(FForm)3(diglyme)], respectively.
A
Nd complex of N,N0-bis(2,3,4,5-tetrafluorophenyl)for-
mamidine (TFFormH): [Nd(TFForm)3(dme)], was also prepared by a similar RTP reaction, and was crys-
tallised from dme. Heating the previously reported divalent TFForm complex: [Yb(TFForm)2(thf)3], in
either PhMe or diglyme, separated out trace amounts of the trivalent complex [Yb(TFForm)3(thf)2] from
PhMe, or the mixed oxidation state, solvent separated ion pair (SSIP) [Yb(TFForm)(diglyme)2][Yb
(TFForm)4] from diglyme. The SSIP complex is the first crystallographically characterised trivalent ytter-
bium complex coordinating four discrete amidinate ligands.
Fluorinated ligands
Formamidinates
Structures
Crown Copyright Ó 2015 Published by Elsevier Ltd. All rights reserved.
1. Introduction
[20]. When ArForm ligands of low bulk are coordinated, namely
N,N0-bis(4-methylphenyl)formamidinate (p-TolForm), the thf
In efforts to explore N-donor based alternatives to cyclopentadi-
enyl-type ligands [1–10], our attention has focused on tꢁhe coordi-
nation of N,N0-bis(aryl)formamidinate ligands ({ArForm} ), to rare-
earth metals [11–17]. ArFormH ligands can be readily prepared
from an acid catalysed reaction between a functionalised aniline
and triethyl orthoformate (Scheme 1) [12,18].
Thus, with a wide variety of different ArForm ligands available,
several different aspects of rare-earth ArForm chemistry has been
investigated, providing [Ln(ArForm)3(solv)n] (n = 0–2) [11] and [Ln
(ArForm)2(solv)n] (n = 2, 3) [12] complexes. Through the coordina-
tion of the sterically demanding DippForm (DippFormH = N,N0-bis
(2,6-diisopropylphenyl)formamidine) ligand to rare-earth ions, it
is possible to generate terminal fluorides, namely [Ln(DippForm)2F
(thf)] (Ln = La, Ce, Nd, Sm, Tm) [11,17], from C–F activation
reactions, or products from the reduction of benzophenone or CS2
solvated complexes, [Ln(p-TolForm)3(thf)2] (Ln = La, Ce, Nd, Sm),
rapidly dimerise into [{Ln(p-TolForm)3}2] (Ln = La, Ce, Nd, Sm),
losing coordinated thf under mild conditions and adopting
l-1j
(N,N0):2 (N,N0) coordination [14].
j
Recently fluorinated based ArForm ligands have attracted
our attention [13,21]. We recently reported that homoleptic
[La(CF3Form)3] (CF3FormH = N,N0-bis(2-trifluoromethylphenyl)for-
mamidine), when heated in PhMe [13], rapidly decomposes via a
C–F activation pathway forming LaF3 and two organic species
obtained from the combination of three CF3Form ligands with
one CF3 group completely de-fluorinated [13]. In coordination
chemistry, increasing the number of fluorine atoms on the phenyl
substituent of the ArForm ligand has an impact on the coordination
chemistry of divalent ArForm complexes. When TFForm
(TFFormH = N,N0-bis(2,3,4,5-tetrafluorophenyl)formamidine) was
coordinated to divalent ytterbium [12], it crystallised from a thf
solution as seven coordinate [Yb(TFForm)2(thf)3]ꢀ2thf, whereas all
non-fluorinated ArForm divalent ytterbium compounds crys-
tallised with two coordinated thf ligands, [Yb(ArForm)2(thf)2],
(e.g. ArForm = N,N0-bis(2,6-dimethylphenyl)formamidinate, or
DippForm) [12]. Such an observation is rationalised by the increase
q
Dedicated to Prof. Malcolm Chisholm F.R.S. on the occasion of his 70th birthday
in recognition of his stellar contributions to Inorganic Chemistry.
⇑
Corresponding authors.
E-mail addresses: Glen.Deacon@monash.edu (G.B. Deacon), Peter.Junk@jcu.edu.
au (P.C. Junk), Daniel.werner.07@gmail.com (D. Werner).
http://dx.doi.org/10.1016/j.poly.2015.10.016
0277-5387/Crown Copyright Ó 2015 Published by Elsevier Ltd. All rights reserved.

G.B. Deacon et al. / Polyhedron 103 (2016) 178–186
179
X
X
2-3 drops
CH3COOH
-3 EtOH
+
NH2
CH(OEt)3
2
N
H
N
X
N,N'-bis(aryl)formamidine
X = iPr
= 2-F
= 4-Me = 2,6-F
X = iPr: DippFormH
= 2-F: FFormH
= 4-Me: p-TolFormH = 2,6-F: DFFormH
= 2-CF3: CF3FormH = 2,3,4,5- TFFormH
= 2-CF3 = 2,3,4,5-F
Scheme 1. Synthesis of N,N0-bis(aryl)formamidines (ArFormH) [12,18], and common ArFormH abbreviations [12,13,15,19].
in Lewis acidity of Yb2+ induced by the electron withdrawing fluo-
rine substituents of the TFForm ligand, thereby allowing a higher
coordination number.
[Yb(FForm)2(thf)2] (Yb1)). Varying the excess of Yb metal used in
the RTP reaction enables either divalent or trivalent products. From
thf solutions, the FForm compounds Yb1, [La(FForm)3(thf)2]ꢀthf
(La1), and the Nd analogue [Nd(FForm)3(thf)x] (x = 1–2), required
substantial amounts of vacuum drying to remove solvent.
Although single crystals could not be obtained, the thf:ArForm
ratio for Yb1 and La1 was determined by 1H NMR spectroscopy.
The IR spectrum of La1 suggested that there was both coordinating
thf (893 cmꢁ1), and non-coordinating (926 cmꢁ1) thf. Thus, it is
likely that one of the thf molecules is a lattice solvate. This is sup-
ported by comparison with the cerium N,N0-bis(2,6-diflorophenyl)-
formamidinate (DFForm) analogue, [Ce(DFForm)3(thf)2],[15] which
has only two coordinated thf molecules, with a more fluorinated
ligand, and the o-TolForm La analogue, which has two coordinating
thf ligands and is a mono thf solvate, namely [La(o-TolForm)3
(thf)2]ꢀthf [11].
Herein, we report the coordination of N,N0-bis(2-fluorophenyl)-
formamidinate (FForm) to rare-earth metals: Yb, La, and Nd, isolat-
ing a divalent Yb complex, and three trivalent (La, Nd and Yb)
complexes. In addition, a trivalent neodymium TFForm complex
has been also prepared by RTP reactions. Heating known divalent
[Yb(TFForm)2(thf)3] [12] in either PhMe or diglyme caused separa-
tion of the trivalent species [Yb(TFForm)3(thf)2] (from PhMe), or
the mixed oxidation state, solvent separated ion pair (SSIP) [Yb
(TFForm)(diglyme)2][Yb(TFForm)4] (from diglyme). Both were
structurally characterised. These are the first reported eight coordi-
nate trivalent ytterbium ArForm complexes, and the SSIP contains
the first trivalent ytterbium complex coordinating four discrete
amidinate ligands.
The inability of the FForm complexes to crystallise readily from
thf is surprising considering how easily other ArForm complexes
crystallise from thf [11–13,15,21,22]. However, single crystals are
obtained when the FForm complexes are crystallised from either
dme (La1, Yb1), or diglyme/hexane (‘‘[Nd(FForm)3(thf)x]”) solu-
tions, giving [La(FForm)3(dme)] (La2), [Yb(FForm)2(dme)2] (Yb2),
and [Nd(FForm)3(diglyme)]ꢀdiglyme (Nd1ꢀdiglyme), respectively.
Nevertheless, crystals of the trivalent ytterbium species [Yb
(FForm)3(thf)] (Yb3), are readily obtained from a thf/hexane
solution. The neodymium N,N0-bis(2,3,4,5-tetrafluorophenyl)for-
mamidinate complex, [Nd(TFForm)3(dme)] (Nd2), is readily pre-
pared from RTP reactions in thf, followed by crystallisation from
a dme/PhMe solution. It is noteworthy that before dissolution in
2. Results and discussion
2.1. Synthesis of rare-earth ArForm complexes
The rare-earth ArForm (FForm, or TFForm) complexes are syn-
thesised by redox transmetallation/protolysis (RTP) reactions
between Ln0 metal (Ln = La, Nd, Yb), Hg(C6F5)2, and ArFormH
(FFormH, or TFFormH) in thf (Scheme 2).
The RTP reactions provide an effective route to both
divalent (Yb) and trivalent (La, Nd, Yb) rare-earth complexes,
giving good (50% [Yb(FForm)3(thf)], (Yb3)) to high yields (82%,
dme
[Ln(FForm)x(dme)n]
[Yb(FForm)2(thf)2] (Yb1)
Ln = Yb, x 2, n 2 (Yb2)
=
=
=
Ln = La, x 3, n 1 (La2)
=
(i)
dme
R
R
N
H
N
(va)
(vb)
(ii)
[Nd(TFForm)3(dme)] (Nd2)
[La(FForm)3(thf)2]⋅thf (La1)
ArFormH
R = 2-fluorophenyl (FFormH)
R = 2,3,4,5-tetrafluorophenyl (TFFormH)
(iiia)
(iiib)
(iv)
[Yb(FForm)3(thf)] (Yb3)
[Nd(FForm)3(diglyme)] (Nd1)
Scheme 2. Synthesis of rare-earth ArForm (ArForm = FForm, or TFForm) complexes by RTP reactions. (i) Yb0 (excess), Hg(C6F5)2, 2 FFormH, thf, sonication 1 d, ꢁHg0, ꢁ2
C6F5H; (ii) La0, 1.5 Hg(C6F5)2, 3 FFormH, thf, 60 °C 2 d, ꢁ1.5 Hg0, ꢁ3 C6F5H; (iiia): Nd0, 1.5 Hg(C6F5)2, 3 FFormH, thf, sonication 2 d, ꢁ1.5 Hg0, ꢁ3 C6F5H; (iiib) diglyme/hexane;
(iv) Yb0 (slight excess), 1.5 Hg(C6F5)2, 3 FFormH, thf, room temperature, 2 d, ꢁ1.5 Hg0, ꢁ3 C6F5H; (va): Nd0, 1.5 Hg(C6F5)2, 3 TFFormH, thf, sonication 2 d, ꢁ1.5 Hg0, ꢁ3 C6F5H;
(vb) evaporation then crystallisation from dme/PhMe.

180
G.B. Deacon et al. / Polyhedron 103 (2016) 178–186
dme, the thf adduct did not require substantial vacuum drying to
give a fine flowing powder by contrast with Yb1, La1 and [Nd
(FForm)3(thf)x].
analysis indicated the retention of half a PhMe molecule upon
drying the sample, giving the formula for the bulk product as
[Nd(TFForm)3(dme)]ꢀ1/2PhMe (Nd2ꢀ1/2PhMe).
When the divalent TFForm complex, [Yb(TFForm)2(thf)3] (Yb4)
[12], was heated in PhMe, the complex remained soluble. Upon
several cycles where the solution was evaporated to dryness and
redissolved in PhMe, a dark red insoluble precipitate formed, with
a light yellow supernatant solution. Separation, concentration, and
crystallisation of the yellow residue from a PhMe/hexane solution,
gave a few yellow block crystals. X-ray crystallographic analysis
revealed the formation of trivalent [Yb(TFForm)3(thf)2]ꢀthf/1/2hex-
ane (Yb5). Considering that it was crystallised from a PhMe/Hex-
ane solution, it is surprising that the molecule contains two
bound thf molecules and a lattice thf molecule. In contrast, Yb3
contains only one thf ligand when crystallised from a thf/hexane
solution. It may be that Yb5 is a trace trivalent impurity from the
initial synthesis of Yb4, and through the heating and evaporation
cycles, Yb5 eventually liberates thf, forming the dark red insoluble
powder (probably [Yb(TFForm)2]) leaving residual Yb5 in solution.
When Yb4 was heated in diglyme, a similar process occurred. A red
precipitate formed with a light yellow solution. Crystallisation of
the yellow product from a PhMe/hexane solution yielded two
small crystals of a mixed oxidation state, solvent separated, ion
pair: [Yb(TFForm)(diglyme)2][Yb(TFForm)4] (Yb6). Two previous
SSIP rare-earth ArForm complexes have either Na or K counter ions
[14,17], by contrast with the two Ln complexes of the present
product.
Complex purity was established by either micro elemental anal-
ysis (Yb2, Nd1ꢀdiglyme, Nd2, Yb3) or metal analysis (La2). For
complexes Yb2, La2 and Yb3, the analyses corresponded to the
crystal composition. However for Nd1ꢀdiglyme, the elemental
analysis indicated loss of half the lattice diglyme molecule as
Nd1ꢀ1/2diglyme. Upon further drying the lattice diglyme is com-
pletely removed, as indicated by the absence of free diglyme in
the 1H NMR spectrum of Nd1. The X-ray data for Nd2 indicated
the presence of two disordered, low occupancy PhMe molecules,
but due to their disorder they were omitted from the refinement
process (see X-ray experimental). Nevertheless, the elemental
2.2. Structural discussion
Crystal data for [Yb(FForm)2(dme)2] (Yb2) were solved and
refined in the monoclinic space group C2/c, with half the molecule
(i.e. [Yb0.5(FForm)(dme)]), occupying the asymmetric unit (full
molecule shown in Fig. 1, left). The ytterbium atom is coordinated
by two-trans
j
-(N,N0)FForm ligands, and two dme ligands, giving
the ytterbium centre a coordination number of eight. Not only does
Yb2 have the highest coordination number for a divalent ytterbium
ArForm complex (previous highest: seven coordinate, see above)
[12], but it also has the largest ArForm–ArForm trans angle for
rare-earth ArForm complexes (C7–Yb–C70: 179.68(16)°), and the
dme ligands also coordinate trans to each other (centroid(C15/
C16)–Yb1–centroid(C150/C160): 179.48(15)°). There are several
examples of divalent Ln complexes with two dme ligands
crystallographically characterised [23], but the vast majority con-
tain cisoid anionic ligands [23], such as [Yb(N(SiMe3)Ph)2(dme)2]
(N–Yb–N0: 110.09(7)) [24], or [Yb(Ph2pz)2(dme)2] (Ph2pzH = 3,
5-diphenylpyrazole,
N : 101.37(11)) [25],
(centroid)–Yb–N0(centroid)
but eight coordinate [Yb(Azin)2(dme)2] (AzinH = 7-azaindole)
[26], has a similar ligand array to Yb2, but with a much smaller
transoid angle (C9–Yb1–C18: 141.5(2)°).
X-ray data for [La(FForm)3(dme)] (La2) were solved and refined
in the monoclinic space group P21/n, with the whole molecule
within the asymmetric unit. The lanthanum atom is coordinated
by three terminal
j
(N,N0) FForm ligands, and one chelating
dme ligand, giving the lanthanum atom a coordination number
of eight. The only two other eight coordinated trivalent ArForm
complexes similar to La2 are [Ce(DFForm)3(thf)2] [15], and
[La(o-TolForm)3(thf)2]ꢀthf [11]. Of these two examples, the FForm
array in La2 resembles that of [La(o-TolForm)3(thf)2]ꢀthf, as each
FForm or o-TolForm ligand coordinates in an independent ligand
plane (meaning there are three NCN ArForm planes and one
solvent plane), whereas there are two coordination planes in
Fig. 1. Molecular structures of [Yb(FForm)2(dme)2] (Yb2, left), and [La(FForm)3(dme)] (La2, right). Ellipsoids shown at 50% probability, and hydrogen atoms removed for
clarity. Selected bond lengths (Å) and angle (°) for Yb2: Yb1–N1: 2.502(4), Yb1–N2: 2.515(4), Yb1–O1: 2.605(3), Yb1–O2: 2.608(3), C1–Yb1–C10: 179.70. Selected bond lengths
(Å) and angle (°) for La2: La1–N1: 2.578(7), La1–N2: 2.588(7), La1–N3: 2.551(7), La1–N4: 2.617(7), La1–N5: 2.577(6), La1–N6: 2.580(6), La1–O1: 2.599(6), La1–O2: 2.660(6),
C7–La1–C20: 133.6(2), C20–La1–C33: 87.1(2), C33–La1–C7: 108.4(2).

G.B. Deacon et al. / Polyhedron 103 (2016) 178–186
181
[Ce(DFForm)3(thf)2] (one slightly twisted plane containing two
DFForm ligands, and one plane containing one DFForm ligand
and two thf ligands). This difference in arrangement might be
attributed to the size of the rare-earth metal, as the ArForm
coordination in the complex [Yb(o-TolForm)3(thf)] of the smaller
Yb3+, also exhibits two ligand planes: one ligand plane containing
two o-TolForm ligands, and one plane containing the thf and the
third o-TolForm ligand [11]. It is noteworthy that with the bulkier
N,N0-bis(2,6-diethylphenyl)formamidinate (EtForm) complexes,
[Ln(EtForm)3] (Ln = La, Ce, Nd, Sm), the EtForm coordination array
is the same across all the metals [11,15].
X-ray data for Nd2 were solved and refined in the triclinic space
group P1 with two molecules within the asymmetric unit (Fig. 2,
ꢀ
right, only one representative molecule shown). Two highly disor-
dered, low occupancy PhMe molecules were present in the asym-
metric unit, but due to difficulties in their refinement, their
electron density was removed by the SQUEEZE program. The Nd
atom is coordinated by three terminal
j
(N,N0) TFForm ligands,
and one dme molecule, giving the Nd centre a coordination num-
ber of eight. Nd2 is the first reported example of a trivalent rare-
earth TFForm complex. Unlike Nd1 and La2 which have the FForm
ligands dispersed around the metal coordination sphere, the
TFForm ligands in Nd2 favour one side of the coordination sphere,
coordinating away from the dme ligand. This close TFForm–
TFForm proximity gives rise to very low C–Nd–C angles (e.g.
C7–Nd1–C20: 86.09(11)°). With the exception of Yb5, each triva-
lent complex has at least one small C–Ln–C angle. However in
Nd2 the sum of all three C–Nd–C0 angles (294.13°) is much smaller
than the sum of the analogous angles of Nd1 (324.27°), La2
(329.1°), Yb3 (337.4°) or Yb5 (359.98°). There appear to be no
obvious supramolecular interactions (e.g. o-Hꢀ ꢀ ꢀF) which provide
a significant influence to the TFForm coordination.
The structure of [Nd(FForm)3(diglyme)]ꢀdiglyme (Nd1ꢀdiglyme)
was solved and refined in the monoclinic space group C2/c with the
whole molecule and one diglyme of crystallisation within the
asymmetric unit (Fig. 2, left). The neodymium atom is coordinated
by three terminal
j
(N,N0) FForm ligands, and one diglyme ligand,
giving the neodymium atom a coordination number of nine.
Although a high coordination number for trivalent ArForm com-
plexes, higher numbers of 10 and 12 are known in the unsolvated
complexes [Ce(DFForm)3], and [La(CF3Form)3], respectively
[13,27], owing to intramolecular Ln–F interactions. However,
dissolution of [Ce(DFForm)3] in thf produces eight coordinate
[Ce(DFForm)3(thf)2], a process which is irreversible [15], and nine
coordinate [Ln(ArForm)3(thf)3] complexes are not known. The
steric repulsion by diglyme is less than that of three thf ligands.
Nd1 contains three ligand planes, one plane containing two FForm
ligands (C7, C33), one plane has the diglyme ligand, and one plane
the final FForm ligand (C20). It is noteworthy that C20 of the third
FForm ligand is anent the diglyme coordination plane, with the
nitrogen atoms (N3, N4) being perpendicular to this plane. Surpris-
ingly, a search of the Cambridge structural database indicated
there are currently no crystallographically characterised rare-earth
The X-ray data for [Yb(FForm)3(thf)] (Yb3), were solved and
refined in the monoclinic space group P21/c, with the whole mole-
cule within the asymmetric unit (Fig. 3, left). The seven coordinate
ytterbium complex has two coordination planes, one with two j(N,
N0) FForm ligands (N1, N2; N3, N4) and one plane coordinating one
thf and one FForm ligand (N5, N6).
The trivalent TFForm complex Yb5, crystallises in the triclinic
ꢀ
space group P1 with the whole molecule, a thf molecule, and a half
hexane molecule within the asymmetric unit (Fig. 3, right). There
are two clear coordination planes within the molecule, one coordi-
nating two TFForm ligands (N1, N2/N3, N4), and the other contain-
ing the two thf ligands and a TFForm ligand (N5/N6). Unlike the
arrangement in Nd2, the TFForm ligands are distributed evenly
around the ytterbium centre, giving rise to large C–Yb–C0 angles
(sum: 359.98°). The additional thf molecule in the crystal structure
amidinate complexes with diglyme ligated in a j
(O,O0,O00) manner
[23], and only one other ArForm complex containing coordinating
diglyme, namely [{Eu2(FForm)3(O2)(OH)(diglyme)}2] where the
diglyme ligand is bridging in a l2-1j j
(O,O0):2 (O00) manner [22].
Fig. 2. Molecular structures of [Nd(FForm)3(diglyme)]diglyme (Nd1, left), and [Nd(TFForm)3(dme)] (Nd2, right). Ellipsoids shown at 50% probability, hydrogen atoms and
lattice solvent were removed for clarity. Selected bond lengths (Å) and angle (°) for Nd1: Nd1–N1: 2.495(3), Nd1–N2: 2.645(3), Nd1–N3: 2.555(3), Nd1–N4: 2.570(3), Nd1–
N5: 2.486(3), Nd1–N6: 2.615(3), Nd1–O1: 2.598(2), Nd1–O2: 2.574(2), Nd1–O3: 2.634, C7–Nd1–C20: 102.38(10), C20–Nd1–C33: 87.66(10), C33–Nd1–C7: 134.23(11).
Selected bond lengths (Å) and angle (°) for Nd2: Nd1–N1: 2.539(4), Nd1–N2: 2.539(3), Nd1–N3: 2.596(3), Nd1–N4: 2.515(3), Nd1–N5: 2.507(3), Nd1–N6: 2.545(3), Nd1–O1:
2.498(3), Nd1–O2: 2.515(3), C7–Nd1–C20: 86.09(11), C20–Nd1–C33: 91.91(11), C33–Nd1–C7: 116.13(11).

182
G.B. Deacon et al. / Polyhedron 103 (2016) 178–186
Fig. 3. Molecular structures of [Yb(FForm)3(thf)] (Yb3, left), and [Yb(TFForm)3(thf)2]ꢀthf/1/2Hexane (Yb5ꢀthf/1/2Hexane, right). Ellipsoids shown at 50% probability, hydrogen
atoms and lattice solvent were removed for clarity. Selected bond lengths (Å) and angle (°) for Yb3: Yb1–N1: 2.356(3), Yb1–N2: 2.380(3), Yb1–N3: 2.353(3), Yb1–N4: 2.368
(3), Yb1–N5: 2.349(3) Yb1–N6: 2.379(3), Yb1–O1: 2.314(2). C7–Yb1–C20: 141.3(1); C20–Yb1–C33: 91.87(10), C33–Yb1–C7: 104.23(10). Selected bond lengths (Å) and angle
(°) for Yb5: Yb1–N1: 2.450(5), Yb1–N2: 2.376(4), Yb1–N3: 2.462(4), Yb1–N4: 2.387(4), Yb1–N5: 2.448(4), Yb1–N6: 2.446(4), Yb1–O1: 2.351(4), Yb1–O2: 2.355(4), C7–Yb1–
C20: 136.00(14); C20–Yb1–C33: 112.43(15), C33–Yb1–C7: 111.55(14), O1–Yb1–O2: 153.36(12).
of Yb5 compared with mono-solvated Yb3, highlights the increase
in the Lewis acidity of Yb3+ from the greater number of electron
withdrawing fluorine substituents in TFForm.
TFForm ligands, and divalent Yb2, coordinated by one terminal j
(N,N0) TFForm ligand, and two tridentate diglyme ligands.
Analysis of the Yb–N bond lengths between the two metals
indicates that the average Yb–N distances are: 2.42 Å for Yb1 and
2.50 Å for Yb2, indicating that Yb1 is trivalent (cf. Yb5:
<Yb–N>:2.43 Å), and Yb2 is divalent (cf. Yb2:<Yb–N>:2.51 Å).
However, the difference is less than that (0.16 Å) between the ionic
radii of eight coordinate Yb2+ and Yb3+ [28]. Compound Yb6
The X-ray data for the mixed oxidation state, SSIP complex, [Yb
(TFForm)(diglyme)2][Yb(TFForm)4] (Yb6), were solved and refined
ꢀ
in the triclinic space group P1, with the whole ion pair within the
asymmetric unit (Fig. 4). The SSIP contains two eight coordinate
ytterbium atoms, trivalent Yb1, which has four terminal
j
(N,N0)
Fig. 4. Molecular structure of [Yb(TFForm)(diglyme)2][Yb(TFForm)4] (Yb6). Atoms shown are as spheres, and hydrogen atoms were removed for clarity. Selected bond lengths
(Å) for Yb6: Yb1–N1: 2.398(10), Yb1–N2: 2.445(10), Yb1–N3: 2.447(10), Yb1–N4: 2.402(9), Yb1–N5: 2.430(11), Yb1–N6: 2.374(9), Yb1–N7: 2.482(9), Yb1–N8: 2.392(11),
Yb2–N9: 2.518(10), Yb2–N10: 2.485(9), Yb2–O1: 2.487(9), Yb2–O2: 2.515(8), Yb2–O3: 2.553(9), Yb2–O4: 2.552(9), Yb2–O5: 2.521(9), Yb2–O6: 2.502(9).

G.B. Deacon et al. / Polyhedron 103 (2016) 178–186
183
contains the third example of a rare-earth complex coordinating
four ArForm ligands to the metal centre, with the first example
being tetravalent [Ce(p-TolForm)4] [15], and the other being charge
separated [K(18-Crown-6)][Sm(p-TolForm)4] [14]. However, what
distinguishes Yb6 from these examples, is the coordination of four
ArForm ligands to a much smaller ytterbium(III) ion. The additional
electron withdrawing fluorine atoms make TFForm a weaker
Lewis base than other ArForm ligands (hence weaker/longer
bonds to Yb3+), but also increases the Lewis acidity of the metal.
Thus, reduced steric repulsion due to the longer Yb–N bond
service of the Campbell Microanalytical Service of The University
of Otago New Zealand or the Elemental analysis service of London
Metropolitan University (Yb3). IR spectra were recorded on a
Perkin–Elmer 1600 Fourier transform infrared spectrometer
= 4000–500 cmꢁ1) as mulls in sodium-dried Nujol, or for Yb3
~
(m
dissolved in C6D6 and pressed in between NaCl plates. Melting
points were measured in sealed glass ampoules under nitrogen
and are uncalibrated. Hg(C6F5)2 [35], and TFFormH [12] were syn-
thesised by literature procedures.
lengths, allows the coordination of four TFForm ligands to Yb3+
.
4.2. FFormH
Currently Yb6 this is the only crystallographically characterised
example of a tetrakisamidinatoytterbium complex. However, there
is one similar example with two dianionic di-benzamidinate
ligands, namely N,N0-propane-1,3-diylbis(N00-(trimethylsilyl)
benzamidinate) (benz), in [Li(dme)3][Yb(benz)2] [29]. In addition,
there are no mixed oxidation state Yb SSIP complexes separated
by diglyme, though there are a few examples separated by dme
[30–34]. Of these examples, those with amide based ligands have
two dianionic ligands around one ytterbium centre [30,31],
such as with (Z)-ethene-1,2-diylbis((2,6-di-isopropyl-phenyl)
amide) in [Yb(tBuC(NC6H3-2,6-iPr2)2}(dme)2][{2,6-iPr2C6H3NC
(H)@C(H)NC6H3-2,6-iPr2}2Yb] [30].
FFormH was synthesised by a modification of a literature proce-
dure [18]: 2-fluoroaniline (5.5 g, 0.05 mol) and triethyl orthofor-
mate (3.3 g, 0.03 mol) were stirred at 70 °C in an unstoppered
round bottom flask with six drops of acetic acid added. The evolved
ethanol, was replaced intermittently with hexane. After one hour
the solution was slowly cooled to RT, and the resulting pure white
solid was filtered off and recrystallised once from acetone, giving
thin white needles of FFormH. Yield: 5.5 g, (96%); mp 159–
160 °C, (lit. mp 153 °C) [36]; IR (KBr, cmꢁ1):
m = 3434 m, 3120 m,
3026 m, 2879 ms, 1671 vs 1618 m, 1606 m, 1589 m, 1518 m,
1494 s, 1468 s, 1454 s, 1321 s, 1272 wm, 1247 m, 1230 s, 1185
s, 1100 s, 1036 s, 997 s, 931 m, 846 m, 808 s, 744 s, 628 w, 609
wm, 559 wm, 508 w, 493 w, 469 w, 456 w; 1H NMR (C6D6,
ppm): d = 7.45, br s, 1H, NCHN; 6.99–6.87, m, 6H, Ar-H(3,5,6);
6.79–6.65, m, 2H, Ar-H(4); 19F NMR (C6D6, ppm): d: ꢁ130.0, s.
3. Conclusion
A series of rare-earth FForm complexes have been synthesised
by means of redox transmetallation/protolysis reactions between
free metals (Yb, La, Nd), Hg(C6F5)2, and N,N0-bis(2-fluorophenyl)-
formamidine in thf. When an excess of Yb metal was used, a diva-
lent complex was isolated, and crystallisation from dme gave the
first eight coordinate YbII ArForm complex, [Yb(FForm)2(dme)2].
When only a small excess of Yb metal was used a trivalent species
[Yb(FForm)3(thf)] was isolated in moderate yield. Two other
trivalent FForm complexes were isolated, namely [La(FForm)3
(dme)] and [Nd(FForm)3(diglyme)]. In addition, three N,N0-bis
(2,3,4,5-tetrafluorophenyl)formamidinate (TFForm) complexes
were obtained, one synthesised from an RTP reaction in thf, and
crystallised from dme/PhMe, namely [Nd(TFForm)3(dme)]. The
other two TFForm complexes were isolated in trace amounts, from
heating divalent [Yb(TFForm)2(thf)3] in PhMe or diglyme giving [Yb
(TFForm)3(thf)2] (from PhMe), and a mixed oxidation state SSIP,
[Yb(TFForm)(diglyme)2][Yb(TFForm)4] (from diglyme). The
complexes are the first reported examples of eight coordinate
ytterbium(III) ArForm complexes.
4.3. [Yb(FForm)2(thf)2] (Yb1)
Yb0 (0.57 g, 3.2 mmol, excess), Hg(C6F5)2 (0.31 g, 0.57 mmol),
and FFormH (0.27 g, 1.2 mmol) were dissolved in thf (20 mL),
and sonicated at 60 °C for one day. Once the mixture had settled,
the solution was filtered and evaporated to dryness in vacuo. The
resulting deep red powder was quickly washed with cold PhMe
and evaporated to dryness giving red [Yb(FForm)2(thf)2]. Yield:
0.36 g, (80%); mp 218–222 °C; IR (Nujol, cmꢁ1):
m
= ꢂ1570 w,
1529 s, 1305 s, 1261 s, 1172 m, 1150 m, 1099 m, 1032 m, 950
vw, 900 vw, 847 vw, 802 s, 722 s; 1H NMR (C6D6, ppm): d = 9.15,
br s, 1H (expected 2H), NCHN; 7.00–6.38, m, 16H, Ar-H; 3.85, br
s, 8H,
a
-thf; 2.47, br s, 8H, b-thf; 19F NMR (C6D6, ppm):
d = ꢁ128.9, s.
4.4. [Yb(FForm)2(dme)2] (Yb2)
[Yb(FForm)2(thf)2] (0.30 g, 0.38 mmol) was dissolved in dme
(5 mL), concentrated in vacuo, filtered and stored at ꢁ30 °C, pro-
ducing thick orange block crystals. X-ray crystallographic analysis
revealed the formation of [Yb(FForm)2(dme)2]. Yield: 0.21 g, (69%);
4. Experimental
4.1. General
mp 222–226 °C; IR (Nujol, cmꢁ1):
m
= ꢂ1570 m, 1534 s, 1305 m,
All products, and Ln0 starting materials, are extremely air- and
moisture-sensitive, requiring use of both vacuum line and glove-
box techniques, with manipulations performed under a nitrogen
atmosphere. Solvents (thf, PhMe, hexane, diglyme, dme) were
dried/purified by distillation over sodium (hexane, PhMe) or
sodium benzophenone ketyl (thf, dme, diglyme), and stored in J.
Young Teflon valve ampoules. Metals were purchased from San-
tuko America and were freshly filed before use. NMR experiments
were recorded on a Bruker Avance 300 MHz spectrometer. Samples
were analysed in J. Young NMR tubes, protecting the samples from
air. For compounds Yb1, La1 and La2, the NCHN integration was
lower than the expected, possibly owing to broadened resonances.
All 19F NMR spectra reported were {1H} decoupled. Microanalyses
were performed on the bulk material by the elemental analysis
1261 s, 1229 m, 1099 s, 1019 m, 862 vw, 845 w, 800 m, 742 m,
722 m; 1H NMR (C6D6, ppm): d = 9.04 s, 2H, NCHN; 6.94, br m,
12H, Ar-H(3,5,6); 6.64, s, 4H, Ar-H(4); 3.29, br s, 20H, dme;
19F NMR (C6D6, ppm): d = ꢁ128.9, br s; 171Yb NMR (C6D6 and
C7D8, ppm) 490 s; Anal. Calc. for C34H38N4O4Yb (815.75): C,
50.06; H, 4.69; N, 6.87. Found: C, 49.89; H, 4.68; N, 7.00%.
4.5. [La(FForm)3(thf)2]ꢀthf (La1)
La0 (0.32 g, 0.23 mmol, excess), Hg(C6F5)2 (0.58 g, 1.1 mmol),
and FFormH (0.50 g, 2.2 mmol) were stirred at 60 °C in thf for
two days. Once the mixture had settled, the solution was filtered
and evaporated to dryness in vacuo. The resulting yellow powder
was washed with PhMe, and evaporated to dryness to yield

184
G.B. Deacon et al. / Polyhedron 103 (2016) 178–186
colourless [La(FForm)3(thf)2]ꢀthf (La1). Yield: 0.59 g, (78%); mp
122–124 °C; IR (Nujol, cmꢁ1):
= 1671 w, 1605 m, 1577 m, 1538
s, 1306 s, 1259 w, 1228 m, 1154 w, 1100 m, 1031 s, 985 w, 944
w, 926 w, 893 vw, 845 vw, 806 w, 722 w; 1H NMR (C6D6, ppm):
d = 8.92, br s, 2H, NCHN (expected 3H); 7.03–6.91, br m, 16H,
solution was filtered and evaporated to dryness in vacuo. The yel-
low powder was dissolved in thf (3 mL), layered with hexane
(1 mL), heated to 60 °C, and slowly allowed to cool, resulting in
thick yellow block crystals. X-ray crystallographic analysis per-
formed on the crystals, giving the formula of [Yb(FForm)3(thf)]
(Yb3), Yield: ꢂ0.31 g (ꢂ50%); mp 144–146 °C; IR (C6D6, cmꢁ1):
~
m
Ar-H; 6.90–6.69, br m, 8 H, Ar-H; 3.97, s, 12H,
a-thf; 1.43, s, 12H,
b-thf; 19F NMR (C6D6, ppm): d = ꢁ127.4, s.
m
= 1647 ms, 1653 ms, 1617 s, 1577 vs 1492 vs 1453 vs 1419 w,
1393 m, 1329 vs 1305 vs 1258 s, 1236 vs 1202 m, 1188 m, 1162
w, 1102 s, 1034 s, 998 s, 954 m, 925 m, 868 ms, 849 s, 812 vs
750 vs 731 m. 1H NMR (C6D6, ppm): d = 86.55, br s, 3H, NCHN;
41.65, br s, 3H, Ar-H; 10.41, br s, 9H, Ar-H; 8.65, br s, 12H, Ar-H;
5.21, br s, 8H, thf; 19F NMR (C6D6, ppm): d = ꢁ115.34, br s; Anal.
Calc. for C43H35F6N2OYb (938.84): C, 55.01; H, 3.76; N, 8.95. Found:
C, 55.73; H, 3.67; N, 9.00%.
4.6. [La(FForm)3(dme)] (La2)
La1 (0.40 g, 0.43 mmol) was dissolved in dme (20 mL). The solu-
tion was concentrated, filtered, and stored at ꢁ30 °C. After three
weeks, thick colourless crystals formed and X-ray crystallography
revealed the formation of [La(FForm)3(dme)] (La1). Yield: 0.25 g,
(71%); mp 164–166 °C; IR (Nujol, cmꢁ1):
m = 1673 w, 1605 m,
1537 vs 1307 s, 1230 vs 1204 ms, 1155 m, 1102 s, 1061 s, 1035
s, 990 m, 946 m, 865 m, 847 m, 809 m, 747 vs 612 w; 1H NMR
(C6D6, ppm): d = 9.08, br s, 2.5H, NCHN (expected 3H); 6.94, br s,
6 H, Ar-H; 6.75, m, 12H, Ar-H; 6.61, m, 6H, Ar-H; 3.32, s, 4H,
dme-CH2, 3.0, s, 6H, dme-CH3. 19F NMR (C6D6, ppm): d = ꢁ127.5
s; Anal. Calc. for C43H37F6LaN6O2 (922.70): La, 15.05. Found: La,
14.77%.
4.10. [Yb(TFForm)3(thf)2] (Yb5) and [Yb(TFForm)(diglyme)2][Yb
(TFForm)4] (Yb6)
[Yb(TFForm)2(thf)3] (Yb4, 0.22 g, 0.21 mmol) was synthesised
by a literature procedure [12], and dissolved in PhMe (20 mL).
The red solution was stirred at 90 °C for two days. The solution
was evaporated (whilst hot) to dryness (in vacuo) and fresh PhMe
was added. This process was repeated twice. Upon standing at RT a
red powder and yellow solution formed. After separation from the
insoluble red powder, the yellow solution was layered with hexane
mixture and stored at ꢁ30 °C producing several small yellow block
crystals after three days. X-ray crystallographic analysis of the
crystals revealed the formation and crystallisation of of [Yb
(TFForm)3(thf)2].thf.1/2hexane (Yb5.thf.1/2hexane); Yield: <2%;
mp 160–162 °C. A similar experiment was performed where Yb4
was heated in diglyme at 60 °C for two days. After heating, the
mixture separated into a yellow solution and red precipitate. After
separation from the red powder, the yellow solution was evapo-
rated to dryness in vacuo. The resulting light yellow powder was
dissolved in a PhMe and hexane mixture, and stored at ꢁ30 °C, pro-
ducing two yellow block crystals after 10 days. One of the crystals
were suitable for X-ray crystallographic analysis, revealing the for-
mation of [Yb(TFForm)(diglyme)2][Yb(TFForm)4] (Yb6).
4.7. [Nd(FForm)3(diglyme)] (Nd1)
Nd0 (0.36 g, 2.5 mmol, excess), Hg(C6F5)2 (0.56 g, 1.0 mmol),
and FFormH (0.48 g, 2.1 mmol) were sonicated in thf (20 mL) for
two days. Once the mixture had settled, the light blue solution
was filtered and evaporated to dryness in vacuo. The resulting light
blue powder was dissolved in diglyme (10 mL), and concentrated
in vacuo. Layering with hexane and storage at ꢁ30 °C afforded light
blue needles. X-ray crystallography revealed the formation of [Nd
(FForm)3(diglyme)]ꢀdiglyme (Nd1ꢀdiglyme), however exposure of
the crystals to vacuum gave [Nd(FForm)3(diglyme)] (Nd1) as a
light blue powder. Yield: 0.47 g, (69%); mp 110–114 °C; IR (Nujol,
cmꢁ1):
m = 1601 m, 1572 vs 1537 vs 1353 s, 1312 vs 1261 m,
1239 s, 1217 s, 1195 ms, 1103 s, 1055 s, 992 m, 940 m, 875 m,
849 m, 806 m, 750 vs 612 vw; 1H NMR (C6D6, ppm): d = 16.80, br
s, 3H, NCHN; 7.27–7.16, br m, 18H, Ar-H(3,5,6); 6.57, br s, 6H,
Ar-H(4); 3.08, br m, 6H, CH3-diglyme; ꢁ1.84, br m, 8H,
CH2-diglyme; 19F NMR (C6D6, ppm): d = ꢁ132.9, br s; Anal. Calc.
for C48H48F6N6NdO4.5 (1039.16, loss of half lattice diglyme, per-
formed on crystals which were partially dried): C, 55.47; H, 4.66;
N, 8.08. Found: C, 55.41; H, 4.98; N, 8.12%.
4.11. X-ray crystallography
Complexes were measured on either a Bruker APEX II CCD
diffractometer (Yb2, La2, Nd1ꢀdiglyme, Nd2, Yb5ꢀthf/1/2hexane,
Yb6) with integration and absorption corrections completed using
4.8. [Nd(TFForm)3(dme)] (Nd2)
APEX II program suite [37], or at the Australian Synchrotron on the
MX1 (Yb3) macromolecular beam line, where the data and integra-
tion were completed by Blu-ice [38] and XDS [39] software pro-
grams. Structural solutions were obtained by either Direct
methods [40], Patterson [40] or charge flipping [41] and solutions
were refined using full matrix least squares methods against F2
using SHELX2013, via the OLEX 2[42] interface.
Nd0 (0.38 g, 2.6 mmol, excess), Hg(C6F5)2 (0.56 g, 1.0 mmol),
and TFFormH (0.71 g, 2.1 mmol) were sonicated for two days in
thf (20 mL). Once the mixture had settled, the light blue
solution was filtered and evaporated to dryness in vacuo. The
resulting light blue powder was dissolved in dme (10 mL), concen-
trated in vacuo, and slight amounts of PhMe were added. Large
yellow block crystals were obtained at ꢁ30 °C suitable for X-ray
crystallography, revealing the formula [Nd(TFForm)3(dme)]ꢀ
1/2PhMe (Nd2ꢀ1/2PhMe). Yield: 0.73 g, (81%); mp 158–161 °C; IR
4.12. [Yb(FForm)2(dme)2] (Yb2)
(Nujol, cmꢁ1):
m = 1625 w, 1559 m, 1507 s, 1299 s, 1262 s, 1209
w, 1161 w, 1052 m, 975 wm, 941 wm, 862 w, 801 w, 722 ms; Anal.
Calc. for C46.5H23F24N6NdO2 (1297.92): C, 43.03; H, 1.78; N, 6.45.
Found: C, 43.00; H, 1.53; N, 6.60%.
C
34H38F4N4O4Yb (M = 815.72 g/mol): monoclinic, space group
C2/c (No. 15), a = 23.1448(11) Å, b = 10.0955(6) Å, c = 15.1972
(8) Å, b = 109.819(2)°, V = 3340.6(3) Å3, Z = 4, T = 123.15 K,
(Mo
) = 2.865 mmꢁ1 Dcalc = 1.622 g/cm3,
12408 reflections
measured (4.448° 6 2 6 54.996°), 3820 unique (Rint = 0.0366,
Rsigma = 0.0367) which were used in all calculations. The final R1
was 0.0416 (I > 2 (I)) and wR2 was 0.1117 (all data). Refinement
l
Ka
,
4.9. [Yb(FForm)3(thf)] (Yb3)
H
Yb0 (0.13 g, 0.75 mmol, small excess), Hg(C6F5)2 (0.52 g,
0.98 mmol), and FFormH (0.46 g, 2.0 mmol) were stirred in thf
(15 mL) for two days at R.T. Once the mixture had settled, the
r
details: Large residual peak remaining in structural solution due
to slight crystal twinning.

G.B. Deacon et al. / Polyhedron 103 (2016) 178–186
185
4.13. [La(FForm)3(dme)] (La2)
a
= 112.99(3)°, b = 105.54(3)°,
c
= 95.99(3)°, V = 4050.4(17) Å3,
Z = 2, T = 100.15 K,
l(Mo Ka
) = 2.447 mmꢁ1, Dcalc = 1.894 g/cm3,
C
43H37F6LaN6O2 (M = 922.70 g/mol): monoclinic, space group
P21/n (No. 14), a = 11.0054(7) Å, b = 21.2121(11) Å, c = 17.2015
(10) Å, b = 97.650(3)°, V = 3979.9(4) Å3, Z = 4, T = 123 K,
(Mo K
= 1.147 mmꢁ1, Dcalc = 1.540 g/cm3, 25595 reflections measured
(3.06° 6 2 6 50°), 6991 unique (Rint = 0.1107, Rsigma = 0.1163)
which were used in all calculations. The final R1 was 0.0597 (>2
44236 reflections measured (2.586° 6 2
unique (Rint = 0.0925, Rsigma = 0.1708) which were used in all calcu-
lations. The final R1 was 0.1176 (I > 2 (I)) and wR2 was 0.2588 (all
data). Refinement details: Crystals diffracted poorly and were
slightly twinned. ISOR command used on NPD atoms.
H 6 60.164°), 22995
l
a
)
r
H
r
(I)) and wR2 was 0.2023 (all data). Refinement details: ISOR
command used on NPD fluorine and carbon atoms that were
disordered.
Acknowledgements
We gratefully acknowledge support from the Australian
Research Council (ARC Discovery: DP 130100152). Part of this
research was undertaken on the MX1 beamlines at the Australian
Synchrotron, Victoria, Australia.
4.14. [Nd(FForm)3(diglyme)]ꢀdiglyme (Nd1ꢀdiglyme)
C
51H55F6N6NdO6 (M = 1106.25 g/mol): monoclinic, space group
C2/c (No. 15), a = 36.4999(15) Å, b = 13.7805(5) Å, c = 20.7940
(8) Å, b = 109.542(3)°, V = 9856.6(7) Å3, Z = 8, T = 123 K,
(Mo K
= 1.132 mmꢁ1, Dcalc = 1.491 g/cm3, 67796 reflections measured
l
a)
Appendix A. Supplementary data
(2.36° 6 2
H 6 50°), 8674 unique (Rint = 0.0558, Rsigma = 0.0331)
CCDC 1423116–1423122 contains the supplementary
crystallographic data for Yb2, La2, Nd1ꢀdiglyme, Nd2,
Yb5ꢀthf/1/2hexane, Yb6, Yb3. These data can be obtained free of
charge via http://www.ccdc.cam.ac.uk/conts/retrieving.html, or
from the Cambridge Crystallographic Data Centre, 12 Union
Road, Cambridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or
e-mail: deposit@ccdc.cam.ac.uk.
which were used in all calculations. The final R1 was 0.0276 (>2
(I)) and wR2 was 0.1084 (all data).
r
4.15. 2[Nd(TFForm)3(dme)] (Nd2)
C86H38F48N12Nd2O4 (M = 2503.76 g/mol): triclinic, space group
ꢀ
P1 (No. 2), a = 13.510(3) Å, b = 17.920(4) Å, c = 19.290(4) Å,
79.13(3)°, b = 88.79(3)°,
= 89.54(3)°, V = 4585.2(16) Å3, Z = 2,
T = 173.15 K, (Mo K
) = 1.276 mmꢁ1, Dcalc = 1.813 g/cm3, 71810
reflections measured (2.16° 6 2 6 57.18°), 23206 unique
(Rint = 0.0485, Rsigma = 0.0648) which were used in all calculations.
The final R1 was 0.0462 (>2 (I)) and wR2 was 0.1408 (all data).
a =
c
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l
a
H
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r
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5240.
C
43H35F6N6OYb (M = 938.81 g/mol): monoclinic, space group
P21/c (No. 14), a = 15.493(3) Å, b = 11.761(2) Å, c = 21.435(4) Å,
b = 95.12(3)°, V = 3890.2(12) Å3, Z = 4, T = 123.15 K,
(syn-
chrotron) = 2.476 mmꢁ1 Dcalc = 1.603 g/cm3, 55795 reflections
measured (2.64° 6 2 6 55°), 8530 unique (Rint = 0.0607,
Rsigma = 0.0402) which were used in all calculations. The final R1
l
,
H
was 0.0405 (>2
r
(I)) and wR2 was 0.1063 (all data). Refinement
ꢀ
details: originally solved in P1, with two identical structures
within the ASU, ran through PLATON and suggested monoclinic
cell, considering the similarities between the two molecules pro-
ceeded to refine in monoclinic cell.
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4.17. [Yb(TFForm)3(thf)2]ꢀthf/1/2hexane (Yb5ꢀthf/1/2hexane)
C52.5H36.5F24N6O3Yb (M = 1428.42 g/mol): triclinic, space group
ꢀ
P1 (No. 2), a = 11.8417(5) Å, b = 12.0464(5) Å, c = 19.1090(8) Å,
= 81.598(2)°, b = 84.677(2)°,
= 87.483(2)°, V = 2683.74(19) Å3,
Z = 2, T = 100.15 K, (Mo K
) = 1.876 mmꢁ1, Dcalc = 1.768 g/cm3,
42670 reflections measured (2.16° 6 2 6 55°), 12287 unique
(Rint = 0.0793, Rsigma = 0.0906) which were used in all calculations.
The final R1 was 0.0434 (>2 (I)) and wR2 was 0.1448 (all data).
a
c
l
a
H
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4.18. [Yb(TFForm)(diglme)2][Yb(TFForm)4] (Yb6)
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C77H43F40N10O6Yb2 (M = 2310.29 g/mol): triclinic, space group
ꢀ
P1 (No. 2), a = 13.674(3) Å, b = 17.597(4) Å, c = 19.530(4) Å,

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