Molecular structures of three coordinate zinc and cadmium complexes that feature β-diketiminato and anilido-imine ligands

Article abstract of DOI:10.1016/j.poly.2010.02.020

A series of zinc and cadmium complexes of the β-diketiminato and anilido-imine classes of ligands, namely [BDI^Ar], [AI^Ar] and [AI^Ar,NPr₂i], have been synthesized and structurally characterized by X-ray diffraction. For example, the zinc and cadmium alkyl compounds [AI^Ar]ZnEt and [AI^Ar]CdMe have been synthesized via the reactions of [AI^Ar]H with Et₂Zn and Me₂Cd, respectively, while [AI^Ar]ZnN(SiMe₃)₂ has been obtained by treatment of [AI^Ar]H with Zn[N(SiMe₃)₂]₂. Single crystal X-ray diffraction studies establish that the metal centers in each of these complexes are trigonal planar. Comparison of the molecular structures of [AI^Ar]CdMe and [BDI^Ar]CdMe demonstrates that the cadmium methyl moiety lies in the plane of the annulated [AI^Ar] ligand, whereas there is considerable displacement for [BDI^Ar]CdMe. [AI^Ar,NPr₂i]Li, an anilido-imine ligand that incorporates a CH₂ CH₂ NPr₂ⁱ tether, has been synthesized via a sequence involving condensation of 2-fluorobenzaldehyde with H₂ NCH₂ CH₂ NPr₂ⁱ, followed by treatment with ArNHLi. X-ray diffraction demonstrates that the lithium has a T-shaped coordination environment which is supplemented by an agostic interaction with a C-H bond of one of the isopropyl groups of the NPr₂ⁱ moiety. However, while the NPr₂ⁱ group of the tether coordinates to lithium in [AI^Ar,NPr₂i]Li, it does not coordinate to the zinc center of [AI^Ar,NPr₂i]ZnMe. The structure of [AI^Ar,NPr₂i]ZnMe is also in marked contrast to that reported for [AI^{Ar, NMe₂}]ZnMe, in which the NMe₂ group does coordinate to the zinc center. The M-C bonds of [AI^Ar,NPr₂i]ZnMe, [BDI^Ar]ZnEt and [BDI^Ar]CdMe are cleaved by B(C₆F₅)₃ to give the perfluorophenyl derivatives [AI^Ar,NPr₂i]ZnC₆F₅, [BDI^Ar]ZnC₆F₅ and [BDI^Ar]CdC₆F₅. Interestingly, the C₆F₅ groups are almost orthogonal to the planes of the chelating ligands in the zinc complexes, [AI^Ar,NPr₂i]ZnC₆F₅ and [BDI^Ar]ZnC₆F₅, whereas the C₆F₅ and [BDI^Ar] ligands of [BDI^Ar]CdC₆F₅ reside in the same plane. In addition to 1:1 [AI^Ar,NPr₂i]ZnX complexes, it is also possible to synthesize the 2:1 complex [AI^Ar,NPr₂i]₂Zn which is consistent with the [AI^Ar,NPr₂i] ligand being less sterically demanding than the [BDI^Ar] ligand.

Full text of DOI:10.1016/j.poly.2010.02.020

Polyhedron 29 (2010) 1881–1890
Contents lists available at ScienceDirect
Polyhedron
journal homepage: www.elsevier.com/locate/poly
Molecular structures of three coordinate zinc and cadmium complexes that
feature b-diketiminato and anilido-imine ligands
*
Keliang Pang, Yi Rong, Gerard Parkin
Department of Chemistry, Columbia University, New York, New York 10027, USA
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of zinc and cadmium complexes of the b-diketiminato and anilido-imine classes of ligands,
Ar;NPri2
namely [BDIAr], [AIAr] and [AI
], have been synthesized and structurally characterized by X-ray dif-
Received 24 January 2010
Accepted 11 February 2010
Available online 23 February 2010
fraction. For example, the zinc and cadmium alkyl compounds [AIAr]ZnEt and [AIAr]CdMe have been syn-
thesized via the reactions of [AIAr]H with Et2Zn and Me2Cd, respectively, while [AIAr]ZnN(SiMe3)2 has
been obtained by treatment of [AIAr]H with Zn[N(SiMe3)2]2. Single crystal X-ray diffraction studies estab-
lish that the metal centers in each of these complexes are trigonal planar. Comparison of the molecular
structures of [AIAr]CdMe and [BDIAr]CdMe demonstrates that the cadmium methyl moiety lies in the
Keywords:
Zinc, Cadmium
b-Diketiminato
Anilido-imine
Alkyl
plane of the annulated [AIAr] ligand, whereas there is considerable displacement for [BDIAr]CdMe.
i
[AIAr;NPr ]Li, an anilido-imine ligand that incorporates a CH2CH2NPr tether, has been synthesized via a
i
2
2
sequence involving condensation of 2-fluorobenzaldehyde with H2NCH2CH2NPri , followed by treatment
Perfluorophenyl
2
with ArNHLi. X-ray diffraction demonstrates that the lithium has a T-shaped coordination environment
which is supplemented by an agostic interaction with a C–H bond of one of the isopropyl groups of the
i
2
NPri2 moiety. However, while the NPri2 group of the tether coordinates to lithium in [AIAr;NPr ]Li, it does not
i
Ar;NPri2
coordinate to the zinc center of [AIAr;NPr ]ZnMe. The structure of [AI
]ZnMe is also in marked contrast
2
to that reported for [AIAr;NMe ]ZnMe, in which the NMe2 group does coordinate to the zinc center. The M–C
2
i
2
bonds of [AIAr;NPr ]ZnMe, [BDIAr]ZnEt and [BDIAr]CdMe are cleaved by B(C6F5)3 to give the perfluorophenyl
i
2
derivatives [AIAr;NPr ]ZnC6F5, [BDIAr]ZnC6F5 and [BDIAr]CdC6F5. Interestingly, the C6F5 groups are almost
i
2
orthogonal to the planes of the chelating ligands in the zinc complexes, [AIAr;NPr ]ZnC6F5 and
[BDIAr]ZnC6F5, whereas the C6F5 and [BDIAr] ligands of [BDIAr]CdC6F5 reside in the same plane. In addition
i
2
Ar;NPri2
to 1:1 [AIAr;NPr ]ZnX complexes, it is also possible to synthesize the 2:1 complex [AI
]2Zn which is
i
2
consistent with the [AIAr;NPr ] ligand being less sterically demanding than the [BDIAr] ligand.
Ó 2010 Elsevier Ltd. All rights reserved.
1. Introduction
X = Et, OAc, OMe, OPri, N(SiMe3)2, Cl, and Br) [15,19,20], some of
which have found applications as catalysts for (i) the copolymeriza-
tion of cyclohexene oxide and CO2, and (ii) the polymerization of lac-
tides [15,20–25]. In view of the many successful applications of the
[BDIAr] ligand, it is, therefore, not surprising that a variety of modi-
fications of this ligand system have been introduced. For example,
Although initially developed in the 1960s [1–6], there has re-
cently been a resurgence in activity concerned with the b-diimi-
nate class of ligands [R0C{C(R00)NR}2], as shown in the protonated
form in Fig. 1 [7–12]. In large part, this revival is due to the advent
of derivatives in which the nitrogen atoms feature bulky substitu-
ents and, in particular, 2,6-diisopropylphenyl groups, i.e. the
[HC{C(Me)NAr}2] ligand ([BDIAr]) [13–15].1 For example, with re-
spect to zinc chemistry, the [BDIAr] ligand has enabled the isolation
of the zinc–zinc bonded complex, [BDIAr]Zn–Zn[BDIAr] [16,17], the
monomeric zinc hydride complex [BDIAr]ZnH [18], and a variety of
other three- and four-coordinate zinc compounds (e.g. [BDIAr]ZnX,
Piers reported the anilido-imine ligand [AIAr] (Ar = 2,6-Pri C6H3)
2
[26–29],2 while others have described variants that feature addi-
tional donor groups [30–32], as illustrated in Fig. 2. Here, we de-
scribe structural aspects of zinc and cadmium complexes derived
from b-diketiminato and anilido-imine classes of ligands, namely
[BDIAr]ZnC6F5, [BDIAr]CdC6F5, [BDIAr]CdMe, [AIAr]ZnEt, [AIAr]CdMe,
Ar;NPri2
Ar;NPri2
Ar;NPri2
[AIAr]ZnN(SiMe3)2, [AI
]ZnMe, [AI
]ZnC6F5, {[AI
]Zn(l–
i
2
OH)}2 and [AIAr;NPr ]2Zn.
* Corresponding author.
E-mail address: Parkin@chem.columbia.edu (G. Parkin).
1
2
Other abbreviations have also been used for the [HC{C(Me)NAr}2] ligand (Ar =
o-Phenylene-bridged bis(anilido-imine) ligands have also been reported. See Refs.
2,6-Pri2C6H3), including BDI, BDI-1 and (dipp)NacNac.
[28,29].
0277-5387/$ - see front matter Ó 2010 Elsevier Ltd. All rights reserved.
doi:10.1016/j.poly.2010.02.020

1882
K. Pang et al. / Polyhedron 29 (2010) 1881–1890
Fig. 1. [R’C{C(R00)NR}2]H.
Fig. 4. Molecular structure of [AIAr]CdMe.
Fig. 2. Examples of b-diketiminate and anilido-imine ligands (in their protonated
forms).
Fig. 5. Molecular structure of [AIAr]ZnN(SiMe3)2.
Scheme 1.
Fig. 3. Molecular structure of [AIAr]ZnEt.
Fig. 6. Molecular structure of [BDIAr]CdMe.

K. Pang et al. / Polyhedron 29 (2010) 1881–1890
1883
Fig. 7. Comparison of the structures of [AIAr]CdMe (left) and [BDIAr]CdMe (right).
i
2
Fig. 8. Molecular structure of [AIAr;NPr ]Li.
structures of [AIAr]ZnEt, [AIAr]CdMe and [AIAr]ZnN(SiMe3)2 have
been determined by X-ray diffraction, as illustrated in Figs. 3–5,
which demonstrate that the metal center in each complex adopts a
three-coordinate trigonal planar geometry.
The trigonal planar geometries of these [AIAr]ZnX complexes are
similar to those of the [BDIAr]ZnX counterparts, namely [BDIAr]ZnEt
[15] and [BDIAr]ZnN(SiMe3)2 [15,33,34].3 In contrast to zinc, how-
ever, few [BDIAr]CdX compounds have been reported [34,35]. There-
fore, for comparison with [AIAr]CdMe, the molecular structure of
[BDIAr]CdMe is illustrated in Fig. 6 and the Cd–Me bond length
[2.126(3) Å] is similar to that in [AIAr]CdMe [2.098(5) Å and
Scheme 2.
2.105(5) Å]. Furthermore, the Cd–Me bond lengths of [AIAr]CdMe
t
and [BDIAr]CdMe are comparable to that for [TpBu ;Me]CdMe which
has a tetrahedral geometry [2.07(2) Å] [36].
1.1. Synthesis and structures of [AIAr]MX (M = Zn, Cd) derivatives
While both [AIAr]CdMe and [BDIAr]CdMe have a similar trigonal
planar geometry, a notable structural difference is that the cad-
mium methyl moiety of [AIAr]CdMe lies in the plane of the annu-
lated [AIAr] ligand, whereas there is considerable displacement
The zinc and cadmium alkyl complexes, [AIAr]ZnEt and
[AIAr]CdMe, are conveniently synthesized via the reactions of [AIAr]H
[26] with Et2Zn and Me2Cd, respectively (Scheme 1). In addition, the
reaction between [AIAr]H and Zn[N(SiMe3)2]2 yields the bis(trimeth-
ylsilyl)amido complex [AIAr]ZnN(SiMe3)2 (Scheme 1). The molecular
3
For other examples of trigonal planar [BDIAr]ZnX complexes, see Refs. [33,34].

1884
K. Pang et al. / Polyhedron 29 (2010) 1881–1890
Scheme 3.
i
Fig. 10. Molecular structure of {[AIAr;NPr ]Zn(
l–OH)}2.
2
i
2
Fig. 9. Molecular structure of [AIAr;NPr ]ZnMe.
i
2
1.2. Synthesis and structures of [AIAr;NPr ]ZnX derivatives
for [BDIAr]CdMe (Fig. 7). For example, the dihedral angle between
the [N2CdC] and [N2C3] planes is 18.6° for [BDIAr]CdMe, but only
2.8° for [AIAr]CdMe. Interestingly, the displacement observed for
[BDIAr]CdMe is not observed for [BDIAr]ZnEt [15].
A variety of tethers that feature donor groups have been incor-
porated into diiminate and anilido-imine ligands as part of an ef-
fort to influence the catalytic ring-opening polymerization of
lactide by changing the Lewis acidity of the metal center [30–

K. Pang et al. / Polyhedron 29 (2010) 1881–1890
1885
Scheme 4.
Fig. 12. Molecular structure of [BDIAr]ZnC6F5.
i
2
Fig. 11. Molecular structure of [AIAr;NPr ]ZnC6F5.
32,37]. For example, the CH2CH2NMe2 tether has been attached to
the anilido-imine ligand and the resulting [AIAr;NMe ]ZnEt complex
2
adopts a distorted tetrahedral geometry due to the coordination
of the NMe2 group [31], in marked contrast to the trigonal planar
structure of [AIAr]ZnEt described above (Fig. 3). Since the ability
of the tether to interact with the metal center would be expected
to be dependent on the nature of the substituents on nitrogen,
we were prompted to synthesize the counterpart with more bulky
Pri groups to determine the extent to which such modification
modulates structure and reactivity.
Access to the desired anilido-imine ligand that incorporates a
i
2
CH2CH2NPri tether, [AIAr;NPr ]Li, is provided via a sequence analo-
Fig. 13. Molecular structure of [BDIAr]CdC6F5.
2
Fig. 14. Comparison of [BDIAr]ZnC6F5 (left) and [BDIAr]CdC6F5 (right).

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K. Pang et al. / Polyhedron 29 (2010) 1881–1890
analogous to that of [BDIAr]ZnC6F5 (Fig. 12), but is very different
to that of the cadmium counterpart [BDIAr]CdC6F5 (Fig. 13) in
which the [BDIAr] and C6F5 ligands reside in the same plane
(Fig. 14). Of these two structures, it is the cadmium structure that
is the more unusual on the basis that a perpendicular arrangement
would have been anticipated to minimize steric interactions. In
this regard, it is worth noting that the structure of a different crys-
talline form of [BDIAr]CdC6F5 [34] exhibits a similar structure to
that described here and so it is not likely that the coplanarity can
be attributed to crystal packing forces. One possible explanation
is that the longer Cd–N and Cd–C bonds, relative to the Zn–N
and Zn–C bonds, result in the ortho fluorine substituents being fur-
ther away from the Ar groups so that the energetic steric penalty
for coplanarity is not as severe as that for the zinc counterpart.
Finally, we note that it is also possible to synthesize the 2:1
i
2
Ar;NPri2
complex [AIAr;NPr ]2Zn via treatment of [AI
]Li with ZnCl2
(Scheme 3), which has been shown by X-ray diffraction to adopt
a pseudo tetrahedral coordination environment (Fig. 15). The
[BDIAr]2Zn counterpart is unknown and ability to isolate the 2:1
i
2
Ar;NPri2
complex [AIAr;NPr ]2Zn is in accord with [AI
cally demanding than the [BDIAr] ligand.
] being less steri-
i
2
Fig. 15. Molecular structure of [AIAr;NPr ]2Zn.
2. Conclusions
In summary, the three coordinate alkyl compounds, [AIAr]ZnEt
and [AIAr]CdMe, have been synthesized via the reactions of [AIAr]H
with Et2Zn and Me2Cd, respectively. The related complex
gous to that for [AIAr;NMe ]H [31], namely condensation of 2-fluoro-
2
benzaldehyde with H2NCH2CH2NPri , followed by treatment with
2
i
2
i
2
Ar;NPri2
ArNHLi (Scheme 2). The molecular structure of [AIAr;NPr ]Li has been
[AIAr;NPr ]ZnMe, in which the [AI
] ligand features an additional
determined by X-ray diffraction, as illustrated in Fig. 8, thereby
demonstrating that the lithium has a T-shaped coordination envi-
ronment. While three-coordinate lithium with a T-shaped geome-
donor group, also possesses a trigonal planar zinc center, which is
in marked contrast to the tetrahedral geometry observed for
[AIAr;NMe ]ZnMe. It is, therefore, evident that the additional bulk
2
try is unusual, it is, nevertheless, precedented [38–41].4 The
associated with the CH2CH2NPri tether reduces its tendency to
2
i
2
coordination geometry of lithium in [AIAr;NPr ]Li is, however, supple-
coordinate to the zinc center, as compared to that for the
i
2
mented by an agostic interaction [42] with a C–H bond of one of the
CH2CH2NMe2 variant. The Zn–C bond of [AIAr;NPr ]ZnMe is cleaved
i
2
isopropyl groups of the NPri2 moiety, with a Liꢀ ꢀ ꢀH distance of 2.3 Å
by B(C6F5)3 to give the perfluorophenyl complex [AIAr;NPr ]ZnC6F5,
[43–49].5
a
transformation that is also observed for [BDIAr]ZnEt and
i
2
The zinc methyl complex [AIAr;NPr ]ZnMe may be obtained by
[BDIAr]CdMe. Interestingly, the C6F5 groups are almost orthogonal
i
2
i
2
treatment of the protonated ligand [AIAr;NPr ]H with Me2Zn
to the planes of the [AIAr;NPr ] and [BDIAr] ligands in the zinc com-
i
2
(Scheme 3). X-ray diffraction demonstrates that the nitrogen of
plexes, [AIAr;NPr ]ZnC6F5 and [BDIAr]ZnC6F5, whereas the C6F5 and
i
2
the NPr2i does not coordinate to the zinc center of [AIAr;NPr ]ZnMe,
[BDIAr] ligands of [BDIAr]CdC6F5 reside in the same plane. In addi-
i
2
such that it is 3-coordinate and planar (Fig. 9). In this regard, the
tion to 1:1 [AIAr;NPr ]ZnX complexes, it is also possible to synthesize
i
2
i
2
molecular structure of [AIAr;NPr ]ZnMe is quite distinct from that
the 2:1 complex [AIAr;NPr ]2Zn, a compound that has no precedent in
of [AIAr;NMe ]ZnEt, which adopts a distorted tetrahedral geometry
the {[BDIAr]Zn} system.
2
due to the coordination of the NMe2 group [22].
i
2
The Zn–C bond of [AIAr;NPr ]ZnMe is a site of facile reactivity. For
example, the Zn–C bond is cleaved by water to give the dinuclear
3. Experimental
i
2
hydroxide-bridged compound {[AIAr;NPr ]Zn(
l
–OH)}2, as illustrated
i
2
in Fig. 10. The zinc methyl compound [AIAr;NPr ]ZnMe also reacts
3.1. General considerations
i
2
with B(C6F5)3 to give the perfluorophenyl complex [AIAr;NPr ]ZnC6F5.
i
2
The formation of [AIAr;NPr ]ZnC6F5 involves the exchange of alkyl
All manipulations were performed using a combination of
glovebox, high-vacuum and Schlenk techniques under a nitrogen
or argon atmosphere, except where otherwise stated. Solvents
were purified and degassed by standard procedures. NMR spectra
were measured on Bruker 300 DRX and Bruker 400 DRX spectrom-
eters. For solutions in organic solvents, 1H NMR spectra are re-
ported in ppm relative to SiMe4 (d = 0) and were referenced
internally with respect to the protio solvent impurity (d 7.16 for
C6D5H) [56]. 13C NMR spectra are reported in ppm relative to SiMe4
(d = 0) and were referenced internally with respect to the solvent (d
128.06 for C6D6) [56]. Coupling constants are given in hertz. IR
spectra were recorded as KBr pellets on a Nicolet Avatar DTGS
spectrometer, and the data are reported in reciprocal centimeters.
Combustion analyses were carried out by Robertson Microlit Labo-
ratories, Madison, NJ, USA. [AIAr]H [26] and [BDIAr]H [14] were syn-
thesized as previously reported.
and perfluorophenyl groups between zinc and boron, a class of
transformation that has precedent [50–55]. Furthermore, [BDIAr]ZnEt
and [BDIAr]CdMe also react with B(C6F5)3 to give [BDIAr]ZnC6F5 and
[BDIAr]CdC6F5 (Scheme 4), although these compounds have been
previously synthesized via the reaction of [BDIAr]H with
Zn(C6F5)2ꢀ2EtCN and Cd(C6F5)2ꢀ2MeCN, respectively [34].
i
2
The molecular structure of [AIAr;NPr ]ZnC6F5 has been deter-
mined by X-ray diffraction which demonstrates that the zinc
adopts a three-coordinate trigonal planar coordination environ-
i
2
ment in which the planes of the [AIAr;NPr ] and C6F5 ligands are al-
most orthogonal to each other (Fig. 11). This type of structure is
4
For other examples of three-coordinate lithium, see Refs. [38–41].
For other examples of lithium compounds with agostic interactions, see Refs. [43–
5
49].

K. Pang et al. / Polyhedron 29 (2010) 1881–1890
1887
3.2. X-ray structure determinations
(30 mL) to give an additional crop of [AIAr]ZnN(SiMe3)2 as a yellow
powder (combined yield: 1.2 g, 27%). Anal. Calc. for C37H57N3Si2Zn:
C, 66.8; H, 8.6; N, 6.3. Found: C, 67.4; H, 8.4; N, 4.8%. 1H NMR
Single crystal X-ray diffraction data were collected on a Bru-
ker P4 diffractometer equipped with a SMART CCD detector.
Crystal data, data collection and refinement parameters are sum-
marized in Table 1. The structures were solved using direct
methods and standard difference map techniques, and were re-
fined by full-matrix least-squares procedures on F2 with SHELXTL
(Version 6.10) [57,58]. The crystallographic data for [AIAr]CdMe,
3
(C6D6): ꢁ0.01 [s, 18H of Si(CH3)3], 1.04 [d, JH–H = 7, 6H of
3
3
CH(CH3)2], 1.11 [d, JH–H = 7, 6H of CH(CH3)2], 1.27 [d, JH–H = 7,
3
6H of CH(CH3)2], 1.44 [d, JH–H = 7, 6H of CH(CH3)2], 3.23 [septet,
3JH–H = 7, 2H of CH(CH3)2], 3.43 [septet, JH–H = 7, 2H of CH(CH3)2],
3
6.34 [t, 3JH–H = 9, 1H of aromatic ring], 6.53 [d, 3JH–H = 9, 1H of aro-
matic ring], 6.82 [t, 3JH–H = 9, 1H of aromatic ring], 6.94 [d, 3JH–H = 9,
1H of aromatic ring], 7.12 [m, protons of aromatic ring], 7.29 [m,
protons of aromatic ring], 8.14 [s,1H of C6H4CH@NAr]. IR Data
(KBr pellet, cmꢁ1): 2961 (s), 2926 (w), 2868 (m), 1622 (s), 1573
(s), 1510 (m), 1462 (s), 1436 (m), 1328 (m), 1173 (w), 1160 (m),
913 (w), 793 (w), 745 (m).
i
2
i
2
[AIAr]ZnEt,
[AIAr]ZnN(SiMe3)2,
[AIAr;NPr ]Li,
[AIAr;NPr ]ZnMe,
i
2
i
2
Ar;NPri2
[AIAr;NPr ]ZnC6F5, {[AI
]Zn(l
–OH)}2, [AIAr;NPr ]2Zn, [BDIAr]CdMe,
[BDIAr]ZnC6F5, and [BDIAr]CdC6F5 have been deposited with the
Cambridge Crystallographic Data Centre (CCDC 762879–762890).
i
The unit cells of [BDIAr]ZnC6F5ꢀ0.25C5H12 and [AIAr;NPr ]2ZnꢀC5H12
,
2
respectively contain 3 and 4 pentane molecules which were
treated as diffuse contributions to the overall scattering without
specific atom positions by use of SQUEEZE/PLATON [59,60].
3.6. Synthesis of [BDIAr]CdMe
Me2Cd (0.15 mL, 2.1 mmol) was added to a solution of [BDIAr]H
(0.84 g, 2.0 mmol) in benzene (10 mL) and refluxed under N2 for
16 h. After this period, an additional quantity of Me2Cd (0.15 mL,
2.1 mmol) was added and the reaction mixture was refluxed under
N2 for a further 16 h. The volatile components were removed in va-
cuo to give a white solid. The solid was extracted into benzene and
the extract was lyophilized to give [BDIAr]CdMe as a white powder
3.3. Synthesis of [AIAr]ZnEt
A solution of [AIAr]H (1.0 g, 2.3 mmol) in benzene (30 mL) was
cooled in an ice/water bath and treated with a solution of Et2Zn
in hexanes (5.0 mL of 1.0 M, 5.0 mmol). The resulting solution
was stirred at room temperature for 1 h and then refluxed for
1 day. After this period, an additional quantity of Et2Zn in hexanes
(2.0 mL of 1.0 M, 2.0 mmol) was added and the resulting solution
was refluxed for an additional day to afford a yellow-green solu-
tion. The volatile components were removed by lyophilization
and the yellow solid residue was extracted into pentane (20 mL).
The solvent was removed in vacuo to give [AIAr]ZnEt as a yellow
(0.93 g, 85%). 1H NMR (C6D6): ꢁ0.37 [s, satellite peaks:
3
2J
= 74, 2J
= 77, 3H of CdCH3], 1.20 [d, JH–H = 7, 12H of
111CdꢁH
113CdꢁH
3
CH(CH3)2], 1.25 [d, JH–H = 7, 12H of CH(CH3)2] 1.74 [s, 6 H of
3
CHC(NAr)CH3], 3.34 [septet, JH–H = 7, 4H of CH(CH3)2], 4.92 [s,
1H of CHC(NAr)CH3], 7.10 [s, 6H of Pri C6H3]. 13C NMR (C6D6):
2
1
ꢁ15.6 [q, JC–H = 129, satellite peaks: 1J
= 886, 1J
= 927,
113CdꢁC
111CdꢁC
3
1
1
powder (1.1 g, 90%). 1H NMR (C6D6): 0.40 [q, JH–H = 8, 2H of
1C of CdCH3], 23.3 [q, JC–H = 125, 4C of CH(CH3)2], 24.1 [q, JC–H
127, 2C of CHC(NAr)CH3], 24.6 [q, JC–H = 125, 4C of CH(CH3)2],
28.2 [d, JC–H = 127, 4C of CH(CH3)2], 94.4 [d, JC–H = 155, 1C of
(NAr)CCHC (NAr)], 123.9 [d, JC–H = 154, 4C of NAr], 125.6 [d, JC–H =
=
3
3
1
CH2CH3], 1.01 [t, JH–H = 8, 3H of CH2CH3], 1.06 [d, JH–H = 7, 6H of
3
3
1
1
CH(CH3)2], 1.14 [d, JH–H = 7, 6H of CH(CH3)2], 1.22 [d, JH–H = 7,
3
1
1
6H of CH(CH3)2], 1.29 [d, JH–H = 7, 6H of CH(CH3)2], 3.11 [septet,
3JH–H = 7, 2H of CH(CH3)2], 3.35 [septet, JH–H = 7, 2H of CH(CH3)2],
158, 2C of NAr], 141.0 [s, C of NAr], 146.5 [s, C of NAr], 167.6 [s,
2C of (NAr)CCHC(NAr)].
3
6.36 [t, 3JH–H = 9, 1H of aromatic ring], 6.54 [d, 3JH–H = 9, 1H of aro-
matic ring], 6.93 [m, 2H of aromatic ring], 7.12 [m, protons of aro-
matic ring], 7.26 [m, protons of aromatic ring], 7.99 [s, 1H of
C6H4CH@NAr].
i
2
3.7. Synthesis of [AIAr;NPr ]Li
(a) 2-fluorobenzaldehyde (10.5 mL, 0.10 mol) and solid MgSO4
(10.0 g, 0.08 mol) was added to a solution of N,N-diisopropylethy-
lenediamine (17.4 mL, 0.10 mol) in hexanes (100 mL). The result-
ing mixture was stirred at room temperature for 2 h and filtered.
The volatile components were removed in vacuo to give 2-F-
3.4. Synthesis of [AIAr]CdMe
A mixture of [AIAr]H (46 mg, 0.10 mmol) and Me2Cd (40
lL,
0.56 mmol) in benzene (0.5 mL) was heated at 110 °C for 3 days.
After this period, the volatile components were removed by lyoph-
ilization and the resulting residue was extracted into pentane
(0.5 mL). Colorless crystals of [AIAr]CdMe were obtained by slow
evaporation at ꢁ15 °C (25 mg, 44%). 1H NMR (C6D6): ꢁ0.35 [s, 3H
C6H4CH = NCH2CH2NPri as yellowish oily liquid (21.0 g, 84%),
2
which was used in the next step without further purification. 1H
3
3
NMR (C6D6): 0.93 [d, JH–H = 7, 12H of CH(CH3)2], 2.75 [t, JH–H
=
3
7, 2H of CH2CH2], 2.89 [septet, JH–H = 7, 12H of CH(CH3)2], 3.60
[t, JH–H = 7, 2H of CH2CH2], 6.7–6.9 [m, 3H on aromatic ring],
3
3
3
of CdCH3], 1.10 [d, JH–H = 7, 6H of CH(CH3)2], 1.14 [d, JH–H = 7,
3
6H of CH(CH3)2], 1.17 [d, JH–H = 7, 6H of CH(CH3)2], 1.24 [d,
8.29 [m, 1H on aromatic ring], 8.60 [s, 1H of CH@NCH2CH2].
3JH–H = 7, 6H of CH(CH3)2] 3.18 [septet, JH–H = 7, 2H of CH(CH3)2],
(b) A solution of diisopropylaniline (6.4 mL, 34 mmol) in
3
3.43 [septet, 3JH–H = 7, 2H of CH(CH3)2], 6.33 [t, 3JH–H = 9, 1H of aro-
THF (20 mL) at ꢁ78 °C was treated with BunLi (1.6 M in hexanes,
24 mL, 38 mmol). The solution was allowed to warm to room
temperature and stirred overnight. After this period,
matic ring], 6.47 [d, 3JH–H = 9, 1H of aromatic ring], 6.88 [t, 3JH–H = 9,
3
1H of aromatic ring], 6.94 [d, JH–H = 9, 1H of aromatic ring], 7.10
[m, protons of aromatic ring], 7.24 [m, protons of aromatic ring],
2-F-C6H4CH@NCH2CH2NPri (3.8 g, 15 mmol) was added and the
2
8.06 [s, 1H of C6H4CH@NAr].
resulting mixture was stirred at room temperature for 1 day. The
reaction was quenched with an aqueous solution of NH4Cl (10%
w/w, 50 mL) and the product was extracted into hexanes
(2 ꢂ 40 mL). The hexane extracts were washed with water
(80 mL) and dried over MgSO4. The solvent was then removed
and the resulting oily residue was dissolved in pentane (30 mL)
and treated with BunLi (1.6 M in hexanes, 12 mL, 19 mmol) at
3.5. Synthesis of [AIAr]ZnN(SiMe3)2
A solution of [AIAr]H (3.0 g, 6.8 mmol) and Zn[N(SiMe3)2]2
(2.6 g, 6.7 mmol) in toluene (30 mL) was refluxed under N2 for
6 days, resulting in the formation of [AIAr]ZnN(SiMe3)2 as a yellow
precipitate which was separated by filtration and washed with
pentane (30 mL). The filtrate was refluxed for an additional
12 days, after which period the volatile components were removed
in vacuo to give a yellow residue, which was washed with pentane
ꢁ78 °C. The resulting mixture was allowed to stir at room temper-
i
2
ature for 1 h to yield [AIAr;NPr ]Li as a yellow solid precipitate, which
was isolated by filtration, washed with cold pentane at ꢁ78 °C
(2 ꢂ 30 mL) and dried in vacuo (5.8 g, 65%). 1H NMR spectroscopy

Table 1
Crystal, intensity collection and refinement data.
[AIAr]CdMe
[AIAr]ZnEt
[AIAr]ZnN(SiMe3)2
[BDIAr]CdMe
[BDIAr]ZnC6F5ꢀ0.25C5H12 [BDIAr]CdC6F5
i
2
i
2
i
2
i
2
i
2
[AIAr;NPr ]Li
[AIAr;NPr ]ZnMe [AIAr;NPr ]ZnC6F5 {[AIAr;NPr ]Zn(
OH)}2
l
–
[AIAr;NPr ]2Znꢀ
C5H12
Lattice
triclinic
orthorhombic triclinic
orthorhombic triclinic
monoclinic
C33H40F5N3Zn
639.05
triclinic
C54H82N6O2Zn2
monoclinic
C59H92N6Zn
950.76
orthorhombic monoclinic
monoclinic
C35H41F5N2Cd
697.10
P21/m
8.7794(16)
20.962(4)
9.9476(19)
90
108.675(3)
90
1734.3(6)
2
Formula
Formula weight
Space group
a (Å)
b (Å)
c (Å)
C32H42N2Cd
567.08
C33H44N2Zn
534.07
Pca21
C37H57N3Si2Zn
C27H40N3Li
413.56
P212121
11.1407(6)
13.8524(8)
16.6396(9)
90
C28H43N3Zn
C30H44N2Cd
545.07
P212121
8.7658(5)
14.5902(9)
21.9488(13)
90
C36.25H44F5N2Zn
668.10
P21/n
18.7547(9)
18.4198(10)
32.8588(17)
90
665.41
487.02
978.00
ꢀ
ꢀ
ꢀ
ꢀ
P21/n
C2/c
P1
P1
P1
P1
9.3452(6)
34.1012(19)
10.6606(11)
11.4633(12)
16.5666(16)
84.949(2)
81.293(3)
74.453(2)
1925.6(3)
2
10.8479(6)
11.3562(7)
11.5527(7)
91.5780(10)
94.1800(10)
100.4410(10)
1394.69(14)
2
14.2013(6)
10.8744(4)
21.8665(9)
90
104.5100(10)
90
10.9646(8)
11.2787(8)
11.4634(8)
77.4830(10)
86.6050(10)
76.9260(10)
1347.99(17)
1
16.0843(9)
18.2035(11)
22.2659(14)
90
105.3330(10)
90
18.0141(14) 9.2401(5)
18.6853(14) 19.4152(9)
76.6850(10) 90
88.626(2)
87.245(2)
3057.2(4)
4
a
(°)
b (°)
90
90
6117.7(6)
8
90
90
90
90
91.4200(10)
90
c
(°)
V (Å3)
Z
2567.9(2)
4
3269.1(2)
4
6287.2(7)
4
2807.1(3)
4
11347.8(10)
12
T (K)
k (Å)
243(2)
0.71073
1.232
0.734
28.31
243(2)
0.71073
1.160
0.825
28.31
41 094
243(2)
0.71073
1.148
0.727
28.30
243(2)
0.71073
1.070
0.062
28.31
243(2)
0.71073
1.160
0.899
28.38
243(2)
0.71073
1.298
0.805
28.35
243(2)
0.71073
1.205
0.933
28.38
243(2)
0.71073
1.004
0.427
28.31
243(2)
0.71073
1.290
0.797
28.31
243(2)
0.71073
1.173
0.698
28.34
243(2)
0.71073
1.335
0.681
28.29
q
l
(g cmꢁ3)
(mmꢁ1
)
h (°)
Number of data
21 504
13 775
18 339
10 055
22 887
9492
22 403
19 593
78 687
11 958
collected
Number of data
used
Number of
parameters
13 582
631
9609
668
8683
389
3457
289
6321
298
7719
379
6032
292
7408
276
6523
313
26 471
1192
4096
207
R1 [I > 2
wR2 [I > 2
R1 [all data]
wR2 [all data]
Goodness-of-fit
(GOF) on F2
r
(I)]
0.0603
0.0638
0.1960
0.0779
1.000
0.0469
0.0786
0.1437
0.0954
1.004
0.0669
0.1116
0.1832
0.1350
1.004
0.0486
0.1308
0.0697
0.1464
1.056
0.0341
0.0818
0.0473
0.0886
1.024
0.0408
0.0946
0.0820
0.1119
1.008
0.0363
0.0941
0.0480
0.1017
1.043
0.0565
0.1070
0.1349
0.1182
1.013
0.0278
0.0520
0.0369
0.0543
1.004
0.0464
0.0981
0.1155
0.1068
1.011
0.0293
0.0733
0.0396
0.0770
1.025
r
(I)]

K. Pang et al. / Polyhedron 29 (2010) 1881–1890
1889
i
2
shows that the product contains ca. 5% 2,6-diisopropylaniline as
NMR spectroscopy which demonstrated that [AIAr;NPr ]ZnC6F5 was
i
2
impurity. Crystals of [AIAr;NPr ]Li suitable for X-ray diffraction were
formed over a period of 1 day at 60 °C. 1H NMR (C6D6): 0.74 [d,
3
obtained by slow evaporation of pentane solution. 1H NMR (C6D6):
3JH–H = 7, 12H of N[CH(CH3)2]2], 1.10 [d, JH–H = 7, 6H of
3
3
3
0.57 [d, JH–H = 7, 12H of N[CH(CH3)2]2], 1.24 [d, JH–H = 7, 6H of
C6H3[CH(CH3)2]2], 1.27 [d, JH–H = 7, 6H of C6H3[CH(CH3)2]2], 2.38
[m, 2H of CH2CH2], 2.62 [septet, JH–H = 7, 2H of CH(CH3)2], 3.19
[m, 2H of CH2CH2], 3.46 [septet, JH–H = 7, 2H of CH(CH3)2], 6.40-
6.53 [m, 2H on aromatic ring], 6.88 [m, 1H on aromatic ring],
7.03 [m, 1H on aromatic ring], 7.22 [m, 3H on aromatic ring],
7.80 [s, 1H of CH@NCH2CH2].
3
3
C6H3[CH(CH3)2]2], 1.27 [d, JH–H = 7, 6H of C6H3[CH(CH3)2]2], 2.13
3
[t, 3JH–H = 6, 2H of CH2CH2], 2.53 [septet, 3JH–H = 6, 2H of CH(CH3)2],
3
3
3.07 [t, JH–H = 6, 2H of CH2CH2], 3.53 [septet, JH–H = 6, 2H of
CH(CH3)2], 6.42–6.48 [m, 2H on aromatic ring], 7.00–7.37 [m, 5H
on aromatic ring], 8.12 [s, 1H of CH@NCH2CH2]. IR Data (KBr pellet,
cmꢁ1): 2962 (vs), 2927 (w), 2868 (m), 1630 (s), 1577 (s), 1511 (m),
1456 (s), 1382 (w), 1362 (w), 1329 (m), 796 (w), 747 (m).
3.11. Synthesis of [BDIAr]ZnC6F5
i
2
3.8. Synthesis of [AIAr;NPr ]ZnMe
A mixture of [BDIAr]ZnEt (20 mg, 0.039 mmol) and B(C6F5)3
(10 mg, 0.020 mmol) was dissolved in benzene (ca. 0.5 mL) and
heated at 80 °C for 1 h. After this period, the volatile components
were removed by lyophilization to give a white solid residue. The
residue was extracted into pentane (ca. 0.5 mL) and colorless crys-
tals of composition [BDIAr]ZnC6F5ꢀ0.25(C5H12) were obtained by
slow evaporation at ꢁ15 °C (15 mg, 59%). Anal. Calc. for
C36.25H44F5N2Zn: C, 65.2; H, 6.6; N, 4.2. Found: C, 65.6; H, 7.4; N,
i
[AIAr;NPr ]Li (1.9 g, 4.6 mmol) was added to an aqueous solution
2
i
2
of NH4Cl (10% w/w, 20 mL) and the generated [AIAr;NPr ]H was ex-
tracted into hexanes (50 mL). The hexanes extract was washed
with water (30 mL) and dried over MgSO4. The volatile compo-
nents were removed in vacuo to give a yellow oil which was dis-
solved in toluene (40 mL), cooled in an ice bath, and treated with
a solution of Me2Zn in toluene (5.0 mL of 2.0 M, 10.0 mmol). The
resulting solution was allowed to warm to room temperature, stir-
3
4.6%. 1H NMR (C6D6): 1.11 [d, JH–H = 7, 12H of CH(CH3)2], 1.26 [d,
red for 4 h, and then stirred at 75 °C for 16 h. The volatile compo-
3JH–H = 7, 12H of CH(CH3)2], 1.67 [s, 6 H of CHC(NAr)CH3], 3.23 [sep-
tet, 3JH–H = 7, 4H of CH(CH3)2], 5.06 [s, 1H of CHC(NAr)CH3], 7.02 [s,
i
2
nents were removed in vacuo to give [AIAr;NPr ]ZnMe as a yellow
i
2
solid (1.8 g, 80%). Crystals of [AIAr;NPr ]ZnMe suitable for X-ray dif-
6H of Pri C6H3].
2
fraction were obtained by slow evaporation of a benzene solution.
Anal. Calc. for C28H43N3Zn: C, 69.1; H, 8.9; N, 8.6. Found: C, 67.9; H,
9.3; N, 8.5%. 1H NMR (C6D6): ꢁ0.30 [s, 3H of Zn–CH3], 0.82 [d, 3JH–H
=
3.12. Synthesis of [BDIAr]CdC6F5
7, 12H of N[CH(CH3)2]2], 1.15 [d, 3JH–H = 7, 6H of C6H3[CH(CH3)2]2],
3
3
1.25 [d, JH–H = 7, 6H of C6H3[CH(CH3)2]2], 2.51 [t, JH–H = 6, 2H of
CH2CH2], 2.72 [septet, JH–H = 6, 2H of CH(CH3)2], 3.23 [t, JH–H = 6,
2H of CH2CH2], 3.32 [septet, JH–H = 6, 2H of CH(CH3)2], 6.40–6.50
A mixture of [BDIAr]CdMe (25 mg, 0.046 mmol) and B(C6F5)3
(11 mg, 0.021 mmol) was dissolved in benzene (ca. 0.5 mL) and al-
lowed to stand at room temperature for 2 h. After this period, the
volatile components were removed by lyophilization to give a
white solid residue. The residue was extracted into pentane
(0.5 mL) and colorless crystals of [BDIAr]CdC6F5 were obtained by
slow evaporation at ꢁ15 °C (ca. 5 mg, 16%). Anal. Calc. for
C35H41CdF5N2: C, 60.3; H, 5.9; N, 4.0. Found: C, 61.8; H, 7.7; N,
3
3
3
[m, 2H on aromatic ring], 6.89–7.30 [m, 5H on aromatic ring],
1
7.85 [s, 1H of CH@NCH2CH2]. 13C NMR (C6D6): ꢁ16.6 [q, JC–H
=
1
121, 1C of Zn–CH3], 21.0 [q, JC–H = 123, 4C of N[CH(CH3)2]2], 24.3
[q, JC–H = 128, 4C of N[CH(CH3)2]2], 24.9 [q, JC–H = 128, 4C of
1
1
1
N[CH(CH3)2]2], 28.2 [d, JC–H = 129, 2C of CH(CH3)2], 46.4 [t,
1JC–H = 131, 1C of CH2CH2], 48.2 [d, JC–H = 132, 2C of CH(CH3)2],
4.3%. 1H NMR (C6D6): 1.15 [d, JH–H = 7, 12H of CH(CH3)2], 1.24 [d,
1
3
1
1
61.0 [t, JC–H = 137, 1C of CH2CH2], 113.2 [d, JC–H = 162, 1C on
3JH–H = 7, 12H of CH(CH3)2], 1.68 [s, 6 H of CHC(NAr)CH3], 3.30 [sep-
tet, 3JH–H = 7, 4H of CH(CH3)2], 4.94 [s, 1H of CHC(NAr)CH3], 7.05 [s,
1
aromatic ring], 114.8 [s, 1C on aromatic ring], 116.6 [d, JC–H
=
159, 1C on aromatic ring], 124.4 [d, JC–H = 155, 1C on aromatic
6H of Pri C6H3].
1
2
1
1
ring], 125.7 [d, JC–H = 159, 1C on aromatic ring], 128.4 [d, JC–H
=
1
159, 1C on aromatic ring], 133.9 [d, JC–H = 156, 1C on aromatic
ring], 137.5 [d, JC–H = 155, 1C on aromatic ring], 144.2 [s, 1C on
i
2
3.13. Synthesis of [AIAr;NPr ]2Zn
1
aromatic ring], 145.1 [s, 1C on aromatic ring], 157.8 [s, 1C on aro-
matic ring], 170.3 [d, 1JC–H = 159, 1C of N@CH]. IR Data (KBr pellet,
cmꢁ1): 2961 (s), 2927 (w), 2866 (m), 1616 (s), 1532 (m), 1470 (s),
1440 (s), 1408 (w), 1381 (w), 1359 (w), 1335 (m), 1244 (w), 1197
(m), 1162 (m), 1036 (w), 793 (w), 757 (m), 748 (w).
i
A solution of [AIAr;NPr ]Li (1.2 g, 2.9 mmol) in THF (20 mL) was
2
added to a solution of ZnCl2 (0.28 g, 2.1 mmol) in THF (30 mL).
The mixture was stirred at room temperature for 1 day and after
this period the volatile components were removed in vacuo. The
residue was extracted with pentane (2 ꢂ 40 mL). The pentane
i
3.9. Synthesis of {[AIAr;NPr ]Zn(
l–OH)}2
extract was concentrated to ca. 20 mL and placed at ꢁ5 °C, there-
2
i
2
by depositing yellow crystals of [AIAr;NPr ]2ZnꢀC5H12 which were
i
Crystals of {[AIAr;NPr ]Zn(
l
–OH)}2 were obtained from a benzene
isolated by filtration, washed with cold pentane (ꢁ78 °C, 10 mL)
and dried in vacuo (0.29 g, 23%). Anal. Calc. for C54H80N6Zn: C,
73.8; H, 9.2; N, 9.6. Found: C, 74.0; H, 9.5; N, 9.3%. 1H NMR
2
i
2
solution via reaction of [AIAr;NPr ]ZnMe with adventitious water. H
NMR (C6D6): ꢁ0.06 [s, 1H of OH (assignment tentative)], 0.88 [d,
1
3
3
3
3JH–H = 7, 12H of N[CH(CH3)2]2], 1.16 [d, JH–H = 7, 6H of
(C6D6): 0.68 [d, JH–H = 7, 6H of C6H3[CH(CH3)2]2], 0.83[d, JH–
3
C6H3[CH(CH3)2]2], 1.33 [d, JH–H = 7, 6H of C6H3[CH(CH3)2]2], 2.18
[m, 2H of CH2CH2], 2.74 [septet, JH–H = 7, 2H of CH(CH3)2], 2.87
[m, 2H of CH2CH2], 3.49 [septet, JH–H = 7, 2H of CH(CH3)2], 6.35
H = 7, 12H of N[CH(CH3)2]2], 0.90 [d, 3JH–H = 7, 12H of
3
3
N[CH(CH3)2]2], 1.03 [d, JH–H = 7, 6H of C6H3[CH(CH3)2]2], 1.22 [d,
3
3
3JH–H = 7, 6H of C6H3[CH(CH3)2]2], 1.34 [d, JH–H = 7, 6H of
[m, 2H on aromatic ring], 6.8–7.3 [m, 5H on aromatic ring], 7.75
[s, 1H of CH@NCH2CH2].
C6H3[CH(CH3)2]2], 2.60 [m, 2H of CH2CH2], 2.72 [m, 2H of
3
CH2CH2],2.78 [septet, JH–H = 7, 4H of CH(CH3)2], 3.10 [m, 2H of
3
CH2CH2], 3.30 [septet, JH–H = 7, 2H of CH(CH3)2], 3.53 [septet,
i
2
3.10. Synthesis of [AIAr;NPr ]ZnC6F5
3JH–H = 7, 2H of CH(CH3)2], 3.85 [m, 2H of CH2CH2], 6.28 [m, 4H
on aromatic ring], 6.72 [m, 2H on aromatic ring], 6.90 [m, 2H
on aromatic ring], 7.04–7.27 [m, 6H on aromatic ring], 7.98 [s,
2H of CH@NCH2CH2].
i
2
A solution of [AIAr;NPr ]ZnMe in C6D6 (0.6 mL) was treated with
B(C6F5)3 (10 mg, 0.020 mmol). The reaction was monitored by 1H

1890
K. Pang et al. / Polyhedron 29 (2010) 1881–1890
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Chem. Soc. 127 (2005) 3031.
CCDC 762879–762890 contain the supplementary crystallo-
graphic data for this paper. These data can be obtained free of
charge via www.ccdc.cam.ac.uk/conts/retrieving.html, or from
the Cambridge Crystallographic Data Centre, 12 Union Road, Cam-
bridge CB2 1EZ, UK; fax: (+44) 1223-336-033; or e-mail:
deposit@ccdc.cam.ac.uk.
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Acknowledgment
We thank the National Science Foundation (CHE-0749674) for
support of this research.
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