Group 2 and 12 metal gallyl complexes containing unsupported Ga-M covalent bonds (M = Mg, Ca, Sr, Ba, Zn, Cd)

Article abstract of DOI:10.1021/om1001606

Reactions of the anionic gallium(I) heterocycle [:Ga(DAB)]^- (DAB = {N(Dip)C(H)}₂, Dip = C₆H₃Prⁱ ₂-2,6) with several group 2 and 12 metal halide complexes are reported. Treatment of in situ

Full text of DOI:10.1021/om1001606

4
914 Organometallics 2010, 29, 4914–4922
DOI: 10.1021/om1001606
Group 2 and 12 Metal Gallyl Complexes Containing Unsupported Ga-M
Covalent Bonds (M=Mg, Ca, Sr, Ba, Zn, Cd)
†
Owen Bonello, Cameron Jones,* Andreas Stasch, and William D. Woodul
School of Chemistry, Monash University, P.O. Box 23, Clayton, Victoria 3800, Australia
Received February 26, 2010
-
Reactions of the anionic gallium(I) heterocycle [:Ga(DAB)] (DAB={N(Dip)C(H)} , Dip=C H -
2
6
3
i
Pr -2,6) with several group 2 and 12 metal halide complexes are reported. Treatment of in situ generated
0 0
MI (tmeda) ] (M = Ca, Sr, Ba; tmeda = N,N,N ,N -tetramethylethylenediamine) with 2 equiv of
2 n
K(tmeda)][:Ga(DAB)] leads to salt elimination and formation of the neutral metal gallyl complexes
2
[
[
trans-[M{Ga(DAB)} (tmeda) ]. Reaction of [(Nacnac)MgI(OEt )] (Nanac = {N(Dip)C(Me)} CH)
2
2
2
2
1
with [K(tmeda)][:Ga(DAB)] gives [(Nacnac)(κ -tmeda)Mg{Ga(DAB)}]. All complexes were crystal-
lographically characterized and display isomerism in solution, which for the latter compound has been
investigated by variable-temperature NMR spectroscopy. The 1:1 reactions of [K(tmeda)][:Ga(DAB)]
with [MX (tmeda)] (M=Zn, X=Br; M=Cd, X=I) yield [(tmeda)MX{Ga(DAB)}], the cadmium
2
example of which is the first molecular complex bearing a Ga-Cd bond. Attempts to reduce these
compounds to low-valent species, e.g. [{(DAB)Ga}MM{Ga(DAB)}], were unsuccessful. Treating
[(Nacnac)Zn(μ-Br) Li(OEt ) ] with [K(tmeda)][:Ga(DAB)] gave [(Nacnac)Zn{Ga(DAB)}], the X-ray
2 2 2
crystal structure of which is reported.
Introduction
also been the subject of intensive investigations in recent
6
years. In this realm, we have been systematically examining
The chemistry of compounds containing metal-metal
bonds has rapidly expanded since Cotton et al. reported
the coordination chemistry of the anionic gallium(I) hetero-
-
cycle [:Ga(DAB)] (1; DAB={N(Dip)C(H)} ; Dip=C H -
3
2
6
2
-
1
the quadruply bonded dianion [Re Cl ] in 1964. The field
i
2
7,8
Pr -2,6), which is a valence isoelectronic analogue of the
2
8
is of enormous fundamental importance and has greatly
added to our understanding of, for example, chemical bond-
important N-heterocyclic carbene (NHC) class of ligand.
The synthetic versatility of this heterocycle has been amply
demonstrated by its use as a Ga-donor ligand in the forma-
tion of complexes with more than 45 elements from all
2
ing, catalysis, and magnetism. In the past decade, the study
of a number of other landmark homonuclear compounds has
stimulated interest in the area and, to some extent, has
redefined the limits of what is synthetically possible. These
include chromium(I) dimers bearing quintuple Cr-Cr bond-
6
a,9
blocks of the periodic table.
Throughout this work, the
coordination chemistry of the heterocycle has shown simila-
rities with, but also significant differences from, that of
0
0
3
10
NHCs, gallium diyls (:Ga R), and neutral gallium(I)
I
6
ing interactions, e.g. [Ar CrCrAr ] (Ar’=bulky terphenyl),
singly bonded zinc(I) dimers, e.g. Cp*ZnZnCp* (Cp* =
4
C Me ), and the first magnesium(I) dimers, e.g. LMgMgL
heterocycles, e.g. six-membered [:Ga(Nacnac)] (Nacnac =
6a,11,12
5
5
{N(Dip)C(Me)} CH)
2
and four-membered [:Ga(Giso)]
13,14
5
(L=bulky guanidinate or β-diketiminate).
(
Giso = {N(Dip)} CNCy , Cy = cyclohexyl).
2
Of most
2
Compounds containing unsupported heteronuclear
0
note is the fact that, like NHCs, the gallium heterocycle 1 is a
strong σ-donor ligand (having a largely sp-hybridized Ga
lone pair) but a weak π-acceptor (despite having an effec-
tively empty Ga p orbital orthogonal to the heterocycle
M-M bonds, involving at least one p-block metal, have
†
Part of the Dietmar Seyferth Festschrift. Dedicated to Professor Dietmar
Seyferth on the occasion of his retirement.
*
To whom correspondence should be addressed. E-mail: cameron.
jones@sci.monash.edu.au.
1) Cotton, F. A.; Curtis, N. F.; Harris, C. B.; Johnson, B. F. G.;
Lippard, S. J.; Mague, J. T.; Robinson, W. R.; Wood, J. S. Science 1964,
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004, 305, 1136. N.B. Reports on a variety of zinc(I) dimers have appeared
(6) See for example: (a) Baker, R. J.; Jones, C. Coord. Chem. Rev.
2005, 149, 1857. (b) Gemel, C.; Steinke, T.; Cokoja, M.; Kempter, A.;
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Symp. Ser. 2002, 822, 2. (g) Linti, G.; Schn €o ckel, H. Coord. Chem. Rev.
2000, 206-207, 285.
(
1
(
(
(
2
(7) Baker, R. J.; Farley, R. D.; Jones, C.; Kloth, M.; Murphy, D. M.
Dalton Trans. 2002, 3844.
(8) A low-yielding synthetic route to the closely related anion
subsequently. See for example: Wang, Y.; Quillian, B.; Wei, P.; Wang, H.;
Yang, X.-J.; Xie, Y.; King, R. B.; Schleyer, P. v. R.; Schaefer, H. F., III;
Robinson, G. H. J. Am. Chem. Soc. 2005, 127, 11944.
t
-
[:Ga{(Bu NCH)}
2
] has been reported: Schmidt, E. S.; Jockisch, A.;
(5) Green, S. P.; Jones, C.; Stasch, A. Science 2007, 318, 1754.
Schmidbaur, H. J. Am. Chem. Soc. 1999, 121, 9758.
pubs.acs.org/Organometallics Published on Web 04/07/2010
r 2010 American Chemical Society

Article
Organometallics, Vol. 29, No. 21, 2010 4915
12e
species: e.g., 6. They also showed that Cp*Ga: can co-
Chart 1
2
ordinate the Zn cation to give the homoleptic complex
þ
2
þ 12e,15
[Zn(GaCp*)4] . Moreover, Fedushkin et al. prepared
the paramagnetic compound 7, the unpaired electron of
which was shown to be located on the Zn heterocycle by
1
6
EPR and computational studies. To the best of our knowl-
edge, no other examples of complexes bearing covalent
gallium-group 2 metal bonds are known, though one
report by Roesky et al. detailed several weak donor-acceptor
compounds involving Cp*Ga: as the Lewis basic ligand, viz.
[
(Cp*Ga) MCp* (THF) ] (M = Ca, Sr, Ba; m = 1, 2;
m 2 n
1
7
n=0, 1). Herein, we detail our efforts to expand the ranks
of compounds containing bonds between gallium and group 2
or group 12 metals. The preparation and structural character-
ization of the first Ga-M (M=Cd, Sr, Ba) covalently bonded
complexes is reported.
plane). Indeed, the ability of the anionic ligand to form
strong polar-covalent bonds with such an array of other
metals is derived from its significant nucleophilicity.
Of most relevance to this study are compounds 2-5
(Chart 1), which incorporate 1 and which represent the first
examples of complexes bearing bonds between gallium and
Results and Discussion
9
i
9e
either group 2 or 12 metals. Subsequent to the reports on
these compounds, several other studies describing Ga-Zn-
bonded species were forthcoming. These included the work
of Fischer et al., who demonstrated that the neutral six-
membered gallium(I) heterocycle [:Ga(Nacnac)] can oxida-
tively insert into Zn-Cl or Zn-C bonds to give zinc gallyl
Group 2 Chemistry. Previously, we showed that the reac-
tions of [K(tmeda)][1] with MI
yield the metal gallyls 2 and 3 but, instead, they give
(M=Mg, Ca) in THF do not
2
9
intractable product mixtures. The eventual preparation of
i
2 and 3 was achieved by the stepwise reduction of the para-
•
magnetic gallium(III) iodide complex [I Ga(DAB )] with
2
9i
either elemental magnesium or calcium in THF. In con-
•
(9) (a) Jones, C.; Stasch, A.; Woodul, W. D. Chem. Commun. 2009,
113. (b) Liddle, S. T.; McMaster, J.; Mills, D. P.; Blake, A. J.; Jones, C.;
trast, reactions between [I Ga(DAB )] and strontium or
2
Woodul, W. D. Angew. Chem., Int. Ed. 2009, 48, 1077. (c) Liddle, S. T.;
Mills, D. P.; Gardner, B. M.; McMaster, J.; Jones, C.; Woodul, W. D. Inorg.
Chem. 2009, 48, 3520. (d) Jones, C.; Mills, D. P.; Rose, R. P.; Stasch, A.
Dalton Trans. 2008, 4395. (e) Jones, C.; Rose, R. P.; Stasch, A. Dalton
Trans. 2007, 2997. (f) Arnold, P. L.; Liddle, S. T.; McMaster, J.; Jones, C.;
Mills, D. P. J. Am. Chem. Soc. 2007, 129, 5360. (g) Green, S. P.; Jones, C.;
Mills, D. P.; Stasch, A. Organometallics 2007, 26, 3424. (h) Green, S. P.;
Jones, C.; Lippert, K.-A.; Mills, D. P.; Stasch, A. Inorg. Chem. 2006, 45,
barium metal did not give analogues of 3 but instead
afforded the partially reduced gallium(II) dimer product
[
of the group 2 metals and that of the lanthanide (Ln) metals
{Ga(DAB)} ]. As there are parallels between the chemistry
2
•
in the þ2 oxidation state, the reduction of [I Ga(DAB )] with
2
elemental Sm, Eu, or Yb was also attempted. Again, complex
product mixtures, not including lanthanide gallyl products,
7
242. (i) Jones, C.; Mills, D. P.; Platts, J. A.; Rose, R. P. Inorg. Chem. 2006,
5, 3146. (j) Baker, R. J.; Jones, C.; Mills, D. P.; Murphy, D. M.; Hey-
9
a
were formed in these reactions. Moreover, lanthanide
4
Hawkins, E.; Wolf, R. Dalton Trans. 2006, 64. (k) Jones, C.; Mills, D. P.;
Rose, R. P. J. Organomet. Chem. 2006, 691, 3060. (l) Aldridge, S.; Baker,
R. J.; Coombs, N. D.; Jones, C.; Rose, R. P.; Rossin, A.; Willock, D. J. Dalton
Trans. 2006, 3313. (m) Aldridge, S.; Baker, R. J.; Coombs, N. D.; Jones, C.;
Rose, R. P.; Rossin, A.; Willock, D. J. Dalton Trans. 2006, 3313. (n) Baker,
R. J.; Jones, C.; Murphy, D. M. Chem. Commun. 2005, 1339. (o) Baker, R. J.;
Jones, C.; Kloth, M. Dalton Trans. 2005, 2106. (p) Baker, R. J.; Jones, C.;
Mills, D. P.; Kloth, M.; Murphy, D. M. Chem. Eur. J. 2005, 11, 2972.
gallyls were not isolated from reactions of [K(tmeda)][1]
0
0
with LnI in THF. However, when N,N,N ,N -tetramethy-
2
lethylenediamine (tmeda) was added to the latter reactions,
the octahedral lanthanide gallyl complexes trans-[Ln{Ga-
(DAB)} (tmeda) ] (Ln = Sm, Eu, Yb), were obtained in
moderate yields.
2 2
9
a,18
Given this success, we decided to revisit
(
q) Baker, R. J.; Jones, C.; Kloth, M.; Platts, J. A. Organometallics 2004, 23,
811. (r) Baker, R. J.; Jones, C.; Kloth, M.; Platts, J. A. Angew. Chem., Int.
Ed. 2003, 43, 2660. (s) Baker, R. J.; Jones, C.; Platts, J. A. Dalton Trans.
003, 3673.
10) (a) Kuhn, N.; Al-Sheikh, A. Coord. Chem. Rev. 2005, 249, 829.
b) Kirmse, W. Eur. J. Org. Chem. 2005, 237. (c) Herrmann, W. A. Angew.
the aforementioned unsuccessful reactions between group 2
metal iodides and [K(tmeda)][1], but including tmeda as a
coreactant.
4
2
(
Treatment of toluene suspensions of MI (M=Ca, Sr, Ba)
2
(
with 2 equiv of [K(tmeda)][1] in the presence of an excess of
tmeda afforded low to good yields of the bis(gallyl) metal
complexes 8-10 (Scheme 1) after recrystallization of the
crude products from diethyl ether. The isolated yield de-
creases with the molecular weight of the group 2 metal
involved. This is possibly due to the expected increasing
Chem., Int. Ed. 2002, 41, 1290. (d) Carmalt, C. J.; Cowley, A. H. Adv. Inorg.
Chem. 2000, 50, 1. (e) Bourissou, D.; Guerret, O.; Gabai, F. B.; Bertrand, G.
Chem. Rev. 2000, 100, 39.
(
11) Hardman, N. J.; Eichler, B. E.; Power, P. P. Chem. Commun.
000, 1991.
12) (a) Prabusankar, G.; Gemel, C.; Parameswaran, P.; Flener, C.;
Frenking, G.; Fischer, R. A. Angew. Chem., Int. Ed. 2009, 48, 5526.
2
(
(
b) Kempter, A.; Gemel, C.; Fischer, R. A. Inorg. Chem. 2008, 47, 7279.
(
c) Prabusankar, G.; Kempter, A.; Gemel, C.; Schr €o ter, M.-K.; Fischer, R. A.
Angew. Chem., Int. Ed. 2008, 47, 7234. (d) Kempter, A.; Gemel, C.;
Cadenbach, T.; Fischer, R. A. Organometallics 2007, 26, 4257. (e) Kempter,
A.; Gemel, C.; Cadenbach, T.; Fischer, R. A. Inorg. Chem. 2007, 46, 9481.
(15) N.B. Two cluster compounds, [MoZn
4
Ga
4 4 4
Me Cp* ] and
[MoZn Ga Me Cp*
8
2
6
4
], which contain Zn-Ga interactions have been
reported: Cadenbach, T.; Bollermann, T.; Gemel, C.; Fernandez, I.; von
Hopffgarten, M.; Frenking, G.; Fischer, R. A. Angew. Chem., Int. Ed.
2008, 47, 9150.
(
f) Kempter, A.; Gemel, C.; Hardman, N. J.; Fischer, R. A. Inorg. Chem.
2
2
006, 45, 3133. (g) Kempter, A.; Gemel, C.; Fischer, R. A. Inorg. Chem.
005, 44, 163. (h) Hardman, N. J.; Wright, R. J.; Phillips, A. D.; Power, P. P.
(16) Fedushkin, I. L.; Lukoyanov, A. N.; Ketkov, S. Y.; Hummert,
J. Am. Chem. Soc. 2003, 125, 2667. (i) Burford, N.; Ragogna, P. J.;
Robertson, K. N.; Cameron, S. T. J. Am. Chem. Soc. 2002, 124, 382.
M.; Schumann, H. Chem. Eur. J. 2007, 13, 7050.
(17) Wieko, M.; Roesky, P. W.; Nava, P.; Ahlrichs, R.; Konchenko,
S. N. Chem. Commun. 2007, 927.
(18) N.B. Several other complexes containing f-block-metal-gallium
bonds have been reported. See: (a) Reference 9b. (b) Reference 9c.
(c) Reference 9f. (d) Wieko, M.; Roesky, P. W. Organometallics 2007,
26, 4846. (e) Minasian, S. G.; Krinsky, J. L.; Rinehart, J. D.; Copping, R.;
Tyliszczak, T.; Janousch, M.; Shuh, D. K.; Arnold, J. J. Am. Chem. Soc.
2009, 131, 13767.
(
j) Hardman, N. J.; Power, P. P. Chem. Commun. 2001, 1184.
13) Jones, C.; Junk, P. C.; Platts, J. A.; Stasch, A. J. Am. Chem. Soc.
006, 128, 2206.
14) (a) Moxey, G. J.; Jones, C.; Stasch, A.; Junk, P. C.; Deacon,
(
2
(
G. B.; Woodul, W. D.; Drago, P. R. Dalton Trans. 2009, 2630. (b) Jones,
C.; Stasch, A.; Moxey, G. J.; Junk, P. C.; Deacon, G. B. Eur. J. Inorg. Chem.
2009, 3593. (c) Green, S. P.; Jones, C.; Stasch, A. Inorg. Chem. 2007, 46, 11.

4
916 Organometallics, Vol. 29, No. 21, 2010
Bonello et al.
Scheme 1
resonances which possibly correspond to the cis isomers of
the compounds (major isomer:minor isomer ratio is ca. 80:20
for all compounds). The most persuasive evidence for this
proposal is that in each spectrum there are signals corres-
ponding to two chemically inequivalent sets of backbone
protons for the gallyl ligands (which resonate as an AB
spin system). The fact that these protons are inequivalent
suggests that the bulky heterocyclic ligands of the “cis
complex” are interlocked and cannot rotate freely with
respect to each other. Very similar spectra have been ob-
served for square-planar transition-metal complexes: e.g.,
9
d
cis-[Pd{Ga(DAB)} (tmeda)]. That the two isomers of
2
8
-10 exist in dynamic equilibrium in solution is borne out
by the fact that dissolving crystallographically authenticated
samples of the trans isomer of each compound in C D led to
6
6
spectra corresponding to isomeric mixtures. Moreover, be-
cause only the trans isomer of each complex can be crystal-
lized from solutions of the isomeric mixtures, it seems that
this is the thermodynamically favored form of the com-
pounds. The low solubility of 8-10 in aromatic solvents at
low temperature precluded variable-temperature NMR stu-
dies of the equilibrium between the isomers.
weakness of the M-Ga bond as the group is descended. In
addition, it appears that for the barium gallyl 10 the chelating
tmeda ligand is more labile than in 8 and 9. This is evidenced
by the fact that, when 10 was recrystallized from diethyl
ether, low yields of the bis(etherate) complex trans-[Ba{Ga-
Compound 11 also exhibits fluxional behavior in solution,
but its enhanced solubility relative to 8-10 allowed this to be
studied by variable-temperature H NMR spectroscopy. At
(DAB)} (tmeda)(OEt ) ] (see the Supporting Information
2 2 2
1
for crystallographic details) consistently cocrystallized
with 10. Addition of a few drops of tmeda to the diethyl
ether solutions of 10 used for recrystallization prevented
3
0 °C the spectrum of the compound exhibits two broad
isopropyl methine resonances and singlet resonances for the
backbone protons of theDAB and Nacnacligands (Figure 1).
When the solution is cooled to -50 °C, the methine reso-
nances resolve into sixbroad septetresonances, theindividual
integration of four of which is slightly greater than that of the
other two. The Nacnac backbone resonance splits into two
singlets, while the DAB backbone signal separates into a
singlet resonance and a broad AB pattern. The relative
integrations of the two sets of both Nacnac and DAB back-
bone resonances is ca. 70:30. A corresponding increase in the
number of methyl and aromatic signals is seen upon sample
cooling, though thecomplexity of overlapping signals inthese
regions make meaningful interpretation difficult. Cooling
the sample below -50 °C led to broadening of all observed
resonances without further resolution, which is probably a
result of a significant increase in the viscosity of the solution
the formation of trans-[Ba{Ga(DAB)} (tmeda)(OEt ) ]. At-
2
2 2
tempts to prepare the mono(gallyl) complexes trans-[MI-
Ga(DAB)}(tmeda) ] using 1:1 reaction stoichiometries
{
2
yielded approximately 50:50 mixtures of 8-10 and unreacted
MI . This suggests that trans-[MI{Ga(DAB)}(tmeda) ] spe-
2
2
cies are unstable with respect to redistribution reactions, as is
common for other heteroleptic heavier group 2 halide com-
1
9
plexes RMX (R=alkyl, amide, etc.; X=halide).
The 2:1 reactions of [K(tmeda)][1] with MgI in THF were
2
also carried out, though no products analogous to 8-10 were
2
0
forthcoming from these. This is not surprising, given the
preference for lower coordination numbers for the smaller
metal, as already exhibited by 2. In order to obtain a mono-
(gallyl) magnesium complex, the β-diketiminate magnesium
complex [(Nacnac)MgI(OEt )] was treated with 1 equiv of
[
2
22
K(tmeda)][1]. This gave a low yield (16%) of 11 (Scheme 1),
and/or partial precipitation of 11 from the solution.
the tmeda ligand of which is derived from the gallium(I)
starting material. Repeating the reaction, but with excess
tmeda added to the mixture, did not lead to an increased
yield of 11. It is noteworthy that the only product identified
from the analogous 2:1 reaction between [K(tmeda)][1]
The spectral pattern displayed by the predominant set of
resonances marked A in Figure 1 is consistent with the solid-
state structure of 11. We cannot be sure what gives rise to the
set of signals marked B in Figure 1, but one possibility is a
more symmetrical isomer of 11, which is in equilibrium with
the predominant isomer. This isomer could be a polymer or
oligomer/cyclic oligomer of 11, viz. [{(DAB)GaMg(Nacnac)-
and dimeric [{(Nacnac)CaI(OEt )} ] was the bis(gallyl) com-
2
2
plex 8, which was isolated in low yield (ca. 15%). It seems
likely that a calcium gallyl complex analogous to 11 ini-
tially forms and then redistributes to 8 and the known
(
μ-tmeda)} ], the trigonal-bipyramidal Mg centers of which
n
are coordinated at their axial sites by two N atoms of bridg-
ing tmeda ligands. It is worthy of note that polymeric
main-group-metal complexes incorporating bridging tmeda
2
1
complex [Ca(Nacnac)2]. That said, the latter complex was
not isolated from the reaction mixture in a pure form.
The spectroscopic data for 8-10 are closely related to
23
ligands are well represented in the literature. Another
possibility is that the B resonances are associated with the
three-coordinate complex [(Nacnac)Mg{(DAB)Ga}], which
is in equilibrium with 11 and free tmeda. However, this is less
likely, as no signals for uncoordinated tmeda were observed
9
a
1
those for trans-[Yb{Ga(DAB)} (tmeda) ]. That is, the H
2
2
NMR spectrum of each displays a major set of resonances
which is consistent with its solid-state structure (vide infra).
The spectra also exhibit more complex, minor sets of
(
19) Westerhausen, M. Coord. Chem. Rev. 2008, 252, 1516.
20) N.B. closely related bis(boryl) magnesium complex,
(THF) ], has been reported: Yamashita, M.; Suzuki,
Y.; Segawa, Y.; Nozaki, K. J. Am. Chem. Soc. 2007, 129, 9570.
21) Harder, S. Organometallics 2002, 21, 3782.
(
A
(22) It is believed that the shoulder on the signal at ca. δ 4.8 ppm in
each spectrum is due to a low-level impurity of unknown composition.
(23) A survey of the Cambridge Crystallographic Database (February
2010) revealed 45 crystallographically characterized examples.
[
Mg{B(DAB)}
2
2
(

Article
Organometallics, Vol. 29, No. 21, 2010 4917
1
Figure 1. Variable-temperature H NMR spectra of [(Nacnac)-
1
Figure 2. Thermal ellipsoid plot (25% probability surface) of
the molecular structure of trans-[Ba{Ga(DAB)} (tmeda) ] (10).
Hydrogen atoms are omitted for clarity.
(
8
κ -tmeda)Mg{Ga(DAB)}] (11) recorded in d -toluene. Reso-
nances associated with the two possible isomers are labeled
A and B.
2
2
at any temperature. The possibility that the minor set of
resonances corresponds to the five-coordinate, tmeda-
˚
Table 1. Selected Bond Lengths (A) and Angles (deg) for 8-10
2
chelated complex [(Nacnac)Mg{(DAB)Ga}(κ -tmeda)] was
8
9
10
also considered. This seems unlikely, as the square-based-
pyramidal and trigonal-bipyramidal forms of this species
Ga-M
3.2568(8)
3
2.574 (mean)
1.936 (mean)
179.24(2)
3.324(1)
3.4625(6)
3.4658(6)
2.868 (mean)
1.941 (mean)
173.62(1)
64.1 (mean)
83.5(1)
.1983(8)
(with the gallyl ligand in apical and equatorial sites, res-
M-N
Ga-N
2.680 (mean)
1.932 (mean)
180.00
72.4(2)
83.7(2)
pectively) should theoretically exhibit four and eight methine
resonances, respectively.
Ga-M-Ga
a
N-M-N
74.6 (mean)
83.4(1)
In the solid state, compounds 8-10 are isostructural
though not isomorphous). As a result, only the molecular
N-Ga-N
(
8
3.6(1)
83.6(1)
structure of 10 is depicted in Figure 2, while selected geome-
trical parameters for each compound are collected in Table 1.
Compounds 8-10 are also isostructural with their lanthanide
counterparts trans-[Ln{Ga(DAB)} (tmeda) ] (Ln = Sm,
a
Both N centers from the same tmeda molecule.
Ga-Mg distance is slightly longer than those in the only
other compound exhibiting such bonds, viz. 2 (2.722 A
˚
2
2
9
a
9i
mean ), despite the higher Mg coordination number in the
latter.
Eu, Yb) and are closely related to 3. Their metal centers
have distorted-octahedral geometries with the gallyl ligands
trans to each other, while the M-Ga and M-N distances in
the compounds increase with the molecular weight of the
group 2 metal. Perhaps surprisingly, the polar covalent
Ga-Ca bonds in 8 are slightly longer than the dative GafCa
Group 12 Chemistry. Although the preparation of hetero-
leptic gallyl group 2 metal iodides was not successful, it was
thought that the expected greater covalency of Ga-group 12
metal bonds might allow the isolation of related heteroleptic
group 12 metal gallyl complexes incorporating 1. Such com-
plexes were seen as potentially useful precursors to access
metal(I) dimers of the type [{(DAB)Ga}MM{Ga(DAB)}]
via reduction methodologies. In this respect 1 can be re-
˚
distance (3.183(2) A) in the adduct complex [Cp* Ca-
(
2
1
7
GaCp*)]. In contrast, the M-Ga separations in 9 and 10
are significantly shorter than in the higher coordination
˚
number complexes [Cp* Sr(GaCp*)(THF)] (3.4348(7) A)
2
˚
and [Cp* Ba(GaCp*) ] (3.591 A mean).
garded as being related to the bulky monodentate terphenyl
0
2
2
Compound 11 was also crystallographically character-
ized, and its molecular structure is depicted in Figure 3. This
shows its magnesium center to have a distorted-tetrahedral
coordination geometry, which includes ligation by the tmeda
molecule through only one of its N centers. Although the
Mg-N(5) bond is significantly longer than either of the
Mg-NNacnac separations, it is at the short end of the reported
ligand C
Power et al. for the stabilization of the homologous series
6
H
3
(Dip)
2
-2,6 (Ar ), which has been utilized by
0
0
26
of complexes [Ar MMAr ] (M=Zn, Cd, Hg).
Whereas the 1:1 reaction of [K(tmeda)][1] with [ZnCl
-
2
2
4
9e
(tmeda)] previously led to intractable product mixtures,
repeating the reaction with [ZnBr (tmeda)] afforded a good
2
isolated yield of the heteroleptic complex 12 after recrystal-
lization from hexane (Scheme 2). A moderate isolated yield
of the cadmium analogue of this compound, viz. 13, was
obtained using a similar synthetic methodology. In contrast,
2
5
˚
range for Mg-Ntmeda interactions (2.10-2.52 A) and
should, therefore, be considered relatively strong. The
the 2:1 reaction of [K(tmeda)][1] with [CdI (tmeda)] led to
2
1
24) Several complexes incorporating κ -tmeda ligands have been
(
previously reported. See for example: Iravani, E.; Neumuller, B.
Organometallics 2003, 22, 4129.
(26) Zhu, Z.; Brynda, M.; Wright, R. J.; Fischer, R. C.; Merrill,
W. A.; Rivard, E.; Wolf, R.; Fettinger, J. C.; Olmstead, M. M.; Power,
P. P. J. Am. Chem. Soc. 2007, 129, 10847.
(25) As determined from a survey of the Cambridge Crystallographic
Database (February 2010).

4
918 Organometallics, Vol. 29, No. 21, 2010
Bonello et al.
Figure 4. Thermal ellipsoid plot (25% probability surface) of
the molecular structure of [(tmeda)ZnBr{Ga(DAB)}] (12).
Hydrogen atoms are omitted for clarity.
Figure 3. Thermal ellipsoid plot (25% probability surface) of
1
the molecular structure of [(Nacnac)(κ -tmeda)Mg{Ga(DAB)}]
(
11). Hydrogen atoms are omitted for clarity. Selected bond
˚
Scheme 2
lengths (A) and angles (deg): Ga(1)-N(2)=1.9238(13), Ga(1)-
N(1) = 1.9360(14), Ga(1)-Mg(1) = 2.7470(7), Mg(1)-N(3) =
2
.0678(15), Mg(1)-N(4)=2.0822(14), Mg(1)-N(5)=2.1733(16);
N(2)-Ga(1)-N(1)=85.55(6), N(2)-Ga(1)-Mg(1)=139.87(4),
N(1)-Ga(1)-Mg(1)=132.15(4), N(3)-Mg(1)-N(4)=91.50(6),
N(3)-Mg(1)-N(5)=110.80(6), N(4)-Mg(1)-N(5)=111.52(6),
N(3)-Mg(1)-Ga(1)=123.35(5), N(4)-Mg(1)-Ga(1)=118.72(4),
N(5)-Mg(1)-Ga(1)=101.20(4).
decomposition with associated deposition of cadmium metal
2
7
and the formation of the gallium(II) dimer [{Ga(DAB)}2].
This outcome attests to the reducing ability of 1, as does the
fact that the 1:1 reaction of [K(tmeda)][1] with [HgI (tmeda)]
2
resulted in the deposition of elemental mercury at ca. -30 °C.
A number of attempts were made to reduce 12 and 13 to
metal-metal-bonded dimers, [{(DAB)Ga}MM{Ga(DAB)}],
using various reagents, e.g. potassium metal, KC , KH, and
ether afforded a good yield of the zinc gallyl complex 14
2
8
8
LiH. In all cases deposition of the group 12 metal occurred at
room temperature. On only one occasion was a soluble pro-
duct identified in these reactions. This came from the reduc-
tion of 12 with LiH in THF and was identified by NMR
spectroscopy and X-ray crystallography (see Supporting
Information) to be the contact ion pair [Li(THF) {H Ga-
as an orange crystalline solid (Scheme 2). In contrast, the
only product isolated from the equivalent reaction of
[K(tmeda)][1] with [(Nacnac)Cd(μ-I)
cadmium gallyl 13, which was obtained in 23% yield.
One explanation for the formation of this compound is
Li(OEt ) ] was the
2
2 2
29
that the starting material, [(Nacnac)Cd(μ-I)
is involved in a “Schlenk equilibrium” with [Cd(Nacnac)
CdI
with CdI
Cd(μ-I) Li(OEt
CdI , which in turn would lead to the formation of more 13.
No further attempts were made to prepare a cadmium
Li(OEt
2
)
2
],
2
2
2
(DAB)}]. One explanation for the formation of this com-
pound involves the generation of a zinc hydride intermediate,
2
],
, and LiI. If so, the preferential reaction of [K(tmeda)][1]
, relative to its reaction with bulkier [(Nacnac)-
], could shift the equilibrium in favor of
2
0
26
e.g. [{(DAB)Ga}ZnH(tmeda)] (cf. [{Ar Zn(μ-H)} ] ), which
2
2
decomposes to Zn metal and [HGa(DAB)] via a hydrogen
transfer process. The neutral gallium hydride species could
then react with excess LiH to give the observed product. No
further attempts were made to reduce 12 or 13.
2
)
2 2
2
Attention then turned to the preparation of group 12
analogues of 11, which are also notionally related to the
previously reported complex 4. Treatment of [(Nacnac)Zn-
(
been reported: Kajiwara, T.; Terabayashi, T.; Yamashita, M.; Nozaki,
K. Angew. Chem., Int. Ed. 2008, 47, 6606.
2
28) N.B. Related zinc boryl complexes, e.g. [Zn{B(DAB)} ], have
(
29) N.B. A small amount of the unusual dicadmium complex
(Nacnac)CdI(μ-I)CdI(μ-I)Li(OEt ] was isolated from one prepara-
tion of [(Nacnac)Cd(μ-I) Li(OEt
(
μ-Br) Li(OEt ) ] with 1 equiv of [K(tmeda)][1] in diethyl
2 2 2
[
2 3
)
3
3
2
2 2
) ] using the literature procedure.
(
27) Pott, T.; Jutzi, P.; Schoeller, W. W.; Stammler, A.; Stammler,
2 3
Crystallographic details of [(Nacnac)CdI(μ-I)CdI(μ-I)Li(OEt ) ] can be
found in the Supporting Information.
H.-G. Organometallics 2001, 20, 5492.

Article
Organometallics, Vol. 29, No. 21, 2010 4919
Figure 5. Thermal ellipsoid plot (25% probability surface) of the molecular structure of the dimeric modification of [(tmeda)CdI-
0
{
Ga(DAB)}] (13). Hydrogen atoms are omitted for clarity. Symmetry operation: ( ) 2 - x, -y, -z.
˚
Table 2. Selected Bond Lengths (A) and Angles (deg) for 12-14
a
b
13
1
2
13
14
Ga-M
M-N
2.3829(8)
2.142(3)
2.509(1)
2.354(5)
2.376(5)
1.870(4)
1.871(4)
2.7202(8)
2.5479(9)
2.384(4)
2.500(4)
1.885(4)
1.899(4)
2.7980(8)
2.3841(6)
1.958(2)
1.958(2)
1.885(2)
1.885(2)
2
.144(3)
1.874(2)
.879(2)
Ga-N
1
c
M-X
2.3598(7)
3
.497(1)
N-M-N
N-Ga-N
85.7(1)
86.8(1)
78.7(2)
86.8(2)
76.0(1)
86.9(2)
98.17(6)
87.13(7)
a
Monomeric modification; data for one of the two crystallographi-
cally independent molecules in the asymmetric unit are shown. Dimeric
b
c
modification. X = Br or I.
1
13
signal was observed in the Cd NMR spectrum of 13, which
is not surprising, as the cadmium center of this compound is
coordinated by quadrupolar gallium and iodine atoms.
In the solid state, the monomeric compounds 12 and 13 are
isostructural, and therefore, only the molecular structure of
1
2 is depicted in Figure 4. Interestingly, compound 13 can
also crystallize as an unsymmetrically iodide bridged dimer
Figure 5). The fact that this compound can cocrystallize as
(
either a monomer or a dimer suggests that its energy of
dimerization is low: i.e., of a similar order as crystal-packing
forces. Selected metrical parameters for 12, both structural
modifications of 13, and the zinc gallyl complex 14 (Figure 6)
can be found in Table 2. The Zn and Cd centers of mono-
meric 12 and 13 have distorted-tetrahedral coordination
geometries, whereas the Cd centers of dimeric 13 are dis-
Figure 6. Thermal ellipsoid plot (25% probability surface) of
the molecular structure of [(Nacnac)Zn{Ga(DAB)}] (14). Hy-
drogen atoms are omitted for clarity.
analogue of 14. It is of note, however, that although 14 is
related to the magnesium gallyl 11, it does not incorporate a
tmeda ligand, even when an excess of tmeda was added to the
reaction mixture that generated it. This is most likely because
0
torted trigonal bipyramidal with N(3) and I(1) taking up the
axial sites. In contrast, the Zn atom of 14 has a trigonal-
planar coordination environment, while the dihedral angle
between its two heterocycles is 55.6°. The gallium atoms in
all the complexes in this study have trigonal-planar geome-
tries. However, the N-Ga-N angles exhibited by the group
12 complexes are significantly more obtuse than those of
the group 2 complexes. This observation is in line with the
expected greater covalent nature of the group 12 metal-Ga
bonds. The Ga-Zn distances in 12 and 14 are close to those
2
þ
2þ
of the lower Lewis acidity of Zn relative to Mg .
All of the complexes 12-14 are thermally stable at room
temperature, though the cadmium gallyl 13 slowly decom-
poses above 50 °C with the deposition of cadmium metal.
1
13
The H and C NMR spectroscopic data for 12-14 are fully
consistent with their solid-state structures (vide infra) and do
not show any indication of the isomerism and/or fluxional
behavior exhibited by the group 2 gallyl complexes 8-11. No

4
920 Organometallics, Vol. 29, No. 21, 2010
Bonello et al.
1
reported for 4 and 6 but slightly shorter than those of
H NMR (300 MHz, C
6
D
6
, 298 K; major isomer): δ 1.26 (d, 24
9
e
3
3
˚
the more sterically crowded species 5 (2.440 A mean ).
Compound 13 possesses the first structurally authenticated
Ga-Cd bonds in a molecular compound, the lengths of
which in each of its structural modifications are well within
H, JHH =6.8 Hz, CH(CH
CH(CH
Hz, CH(CH ) ), 6.55 (s, 4H, NCH), 7.02-7.34 (m, 12 H, Ar-H).
3
)
2
), 1.45 (d, 24 H, JHH =6.8 Hz,
3
) ), 1.89 (br, 32 H, tmeda), 3.95 (sept, 8 H, JHH=6.8
3 2
3 2
1
3
1
C{ H} NMR (100.6 MHz, C
6 6 3 2
D , 300 K): δ 23.7 (CH(CH ) ),
3
0
24.1 (CH(CH ) ), 28.3 (CH(CH ) ), 47.1 (N(CH ) ), 56.1
3 2
˚
3 2
3 2
the sum of the covalent radii (2.66 A) for the two elements.
Both the Zn-Br separation in 12 and the Cd-I distances in
(
(Nujol): 1587 w, 1378 s, 1356 s, 1319 m, 1256 m, 1103 m, 754 m
NCH
2
), 117.2 (NCH), 122.6, 125.0, 145.7, 151.2 (Ar-C). IR
2
5
1
3 are in the normal ranges for such interactions.
-
1
cm . MS (EI 70 eV; m/z (%)): 445.2 (Ga(DAB) , 30), 378.1
þ
þ
iþ
(
DABH , 35), 333.3 (DAB - Pr , 100).
2
Preparation of trans-[Sr{Ga(DAB)} (tmeda) ] (9). A proce-
Conclusions
2
dure similar to that used for the preparation of 8 was employed
for the synthesis of 9: orange crystals (yield 0.14 g, 47%). Mp:
-
In summary, the ability of the gallyl anion [:Ga(DAB)]
1) to participate in salt metathesis reactions with a range of
(
1
1
75-180 °C dec. H NMR (300 MHz, C
6
D
6
, 298 K; major
), 1.46 (d,
24 H, J =6.8 Hz, CH(CH ) ), 1.90 (br, 32 H, tmeda), 3.55
3
group 2 and 12 metal halide complexes has been demon-
strated. These reactions have given rise to a variety of metal
gallyl compounds possessing polar covalent M-Ga (M =
Mg, Ca, Sr, Ba, Zn, Cd) bonds, including the first example
of a cadmium-gallium-bonded molecular species, [(tmeda)-
CdI{Ga(DAB)}]. Crystallographic data on the compounds
have provided evidence that the Ga-M interactions are
more polar for the group 2 metals than for the group 12
metals. Although attempts to stabilize low-valent group 12
complexes using the bulky gallyl ligand 1 have not so far been
successful, we continue to pursue this goal.
3 2
isomer): δ 1.25 (d, 24 H, JHH =6.8 Hz, CH(CH )
3
HH
3 2
3
(sept, 8 H, JHH = 6.8 Hz, CH(CH
7.00-7.34 (m, 12 H, Ar-H). C{ H} NMR (100.6 MHz, C D ,
3
)
2
), 6.57 (s, 4H, NCH),
1
3
1
6
6
3
4
1
1
00 K): δ 23.9 (CH(CH ) ), 24.4 (CH(CH ) ), 28.1 (CH(CH ) ),
3 2 3 2 3 2
5.7 (N(CH ) ), 65.7 (NCH ), 117.1 (NCH), 122.5, 124.9, 142.6,
45.0 (Ar-C). IR (Nujol): 1587 w, 1378 s, 1356 s, 1320 m,
258 m, 1103 m, 754 m cm . MS (EI 70 eV; m/z (%)): 445.2
3
2
2
-
1
þ
þ
iþ
(
Ga(DAB) , 27), 378.1 (DABH , 12), 333.3 (DAB - Pr , 100).
Preparation of trans-[Ba{Ga(DAB)} (tmeda) ] (10). A proce-
2
2
dure similar to that used for the preparation of 8 was employed
for the synthesis of 10: red-orange crystals (yield 0.045 g, 14%).
1
Mp: 178-182 °C dec. H NMR (300 MHz, C D , 298 K; major
6
6
3
Experimental Section
isomer): δ 1.33 (d, 24 H, JHH=6.8 Hz, CH(CH ) ), 1.47 (d, 24
3 2
3
H, JHH =6.8 Hz, CH(CH
3
)
2
), 2.15 (v br, 32 H, tmeda), 3.52
(sept, 8 H, J = 6.8 Hz, CH(CH ) ), 6.61 (s, 4H, NCH),
3
General Methods. All manipulations were carried out using
standard Schlenk and glovebox techniques under an atmo-
sphere of high-purity dinitrogen. Toluene, THF, and hexane
were distilled over potassium while diethyl ether was distilled
HH
3 2
1
3
1
7.02-7.34 (m, 12 H, Ar-H). C{ H} NMR (100.6 MHz, C D ,
300 K): δ 24.2 (CH(CH ) ), 26.3 (CH(CH ) ), 28.4 (CH(CH ) ),
6
6
3
2
3 2
3 2
46.0 (v br, N(CH ) ), 67.0 (v br, NCH ), 117.3 (NCH), 122.7,
3
2
2
1
13
1
over Na/K alloy. H and C{ H} NMR spectra were recorded
on Bruker DXP300 and DRX400 spectrometers and were
referenced to the resonances of the solvents used. Mass spectra
were obtained from the EPSRC National Mass Spectrometric
Service at Swansea University. IR spectra were recorded using a
Nicolet 510 FT-IR spectrometer as Nujol mulls between NaCl
plates. Microanalyses were carried out by Campbell Microana-
lytical, Otago, New Zealand. Reproducible microanalyses
could not be obtained for the group 2 gallyl complexes, due to
their extreme air and moisture sensitivity. Melting points were
determined in sealed glass capillaries under dinitrogen and are
125.0, 142.9 (Ar-C), ipso Ar-C not observed. IR (Nujol): 1586 w,
1377 s, 1356 s, 1319 m, 1261 m, 1101 m, 754 m cm . MS (EI
70 eV; m/z (%)): 445.2 (Ga(DAB) , 100), 378.1 (DABH , 15),
-
1
þ
þ
iþ
333.3 (DAB - Pr , 90).
N.B. If tmeda is not added to the filtered diethyl ether extract
of 10 prior to cooling to -30 °C, trans-[Ba{Ga(DAB)} (tmeda)-
2
(OEt ) ] reproducibly cocrystallizes with 10 in low yield. No
2 2
spectroscopic data have been obtained for this compound.
1
Preparation of [(Nacnac)(K -tmeda)Mg{Ga(DAB)}] (11). A
solution of [K(tmeda)][:Ga(DAB)] (0.37 g, 0.61 mmol) in to-
luene (20 mL) was added over 5 min to a solution of [(Nacnac)-
7
uncorrected. The compounds [K(tmeda)][1], [(Nacnac)MgI-
(
MgI(OEt )] (0.40 g, 0.62 mmol) in toluene (45 mL) at -80 °C.
2
31
32
OEt )], [ZnBr (tmeda)], [CdI (tmeda)], and [(Nacnac)Zn-
32
2
2
2
The mixture was slowly warmed to room temperature and stirred
for 15 h. All volatiles were then removed in vacuo, the residue
was extracted into hexane (20 mL), and the extract was filtered.
The filtrate was then stored at -30 °C overnight, yielding orange
33
(
μ-Br) Li(OEt ) ] were synthesized by variations of literature
procedures. [CaI (OEt ) ] and [MI (THF) ] (M=Sr, Ba) were
2 2 n 2 n
prepared by reacting the freshly filed metal with 1 equiv of
diiodine in either diethyl ether or THF for 5 days. All other
reagents were used as received.
2
2 2
1
crystals of 11 (0.10 g, 16%). Mp: 300-305 °C dec. H NMR
(300 MHz, C D , 298 K): δ 1.09 (br, 36 H, CH(CH ) ), 1.35 (br,
6
6
3 2
Preparation of trans-[Ca{Ga(DAB)} (tmeda) ] (8). A solution
of [K(tmeda)][:Ga(DAB)] (0.30 g, 0.50 mmol) in toluene (15 mL)
was added over 5 min to a suspension of [CaI (OEt ) ]
2
2
3 2 3
12 H, CH(CH ) ), 1.85 (br, 6 H, NCCH ), 1.90 (br, 16 H, tmeda),
3.02 (br, 4 H, Nacnac CH(CH ) ), 3.56 (br, 4 H, DAB
3 2
2
2 n
CH(CH ) ), 4.84 (br s, 2 H, NCCH), 6.26 (br s, 2 H, NCH),
3 2
1
3
1
(
0.25 mmol) in toluene (45 mL) and tmeda (1.0 mL, 6.67 mmol)
7.00-7.15 (m, 12 H, Ar-H). C{ H} NMR (100.6 MHz, C D ,
6
6
at -80 °C. The mixture was slowly warmed to room temperature
and stirred for 15 h. All volatiles were then removed in vacuo,
the residue was extracted into diethyl ether (25 mL), and the
extract was filtered. The filtrate was stored at -30 °C overnight,
yielding orange crystals of 8 (0.21 g, 75%). Mp: 163-165 °C dec.
300 K): δ 23.3, 24.2, 24.6, 25.0, 25.8 (5 ꢀ br, 4 ꢀ CH(CH ) , 1 ꢀ
3
2
CCH ), 28.3, 28.5 (2 ꢀ br, 2 ꢀ CH(CH ) ), 44.8 (v br, N(CH ) ),
3 3 2 3 2
54.1 (v br, NCH ), 95.4 (br, CH), 117.1 (NCH), 122.8, 123.4,
2
124.0, 124.4, 126.2, 141.9, 145.3, 148.3 (8 ꢀ br, Ar-C), 171.2
(CCH ). IR (Nujol): 1520 w, 1377 s, 1364 m, 1316 m, 125 m,
3
-
1
þ
1
tmeda, 21), 445.2 (Ga(DAB) , 100), 418.4 (NacnacH , 22), 403.3
102m, 796m, 756 m cm . MS(EI 70eV;m/z (%)):888.2(M -
þ
þ
(
30) Cordero, B.; Gomez, V.; Platero-Prats, A. E.; Reves, M.;
Echeverria, J.; Cremades, E.; Barragan, F.; Alvarez, S. Dalton Trans.
008, 2832.
31) (a) Bonyhady, S. J.; Jones, C.; Nembenna, S.; Stasch, A.;
þ
iþ
(
NacnacH - CH
Preparation of [(tmeda)ZnBr{Ga(DAB)}] (12). To a solu-
tion of [ZnBr (TMEDA)] (0.17 g, 0.50 mmol) in THF (20 mL)
3
, 45), 333.3 (DAB - Pr , 90).
2
(
2
Edwards, A. J.; McIntyre, G. J. Chem. Eur. J. 2010, 16, 938. (b) Prust,
J.; Most, K.; M €u ller, I.; Alexopoulos, E.; Stasch, A.; Uson, I.; Roesky, H. W.
Z. Anorg. Allg. Chem. 2001, 627, 2032.
at -80 °C was added [K(tmeda)][:Ga(DAB)] (0.30 g, 0.50 mmol)
in THF (20 mL). The reaction mixture was warmed to ambient
temperature over 4 h, whereupon volatiles were removed in
vacuo. The yellow residue was extracted into hexane (50 mL),
the extract was filtered, and the filtrate was stored at -30 °C
(32) Abraham, M. H.; Parret, F. W. Can. J. Chem. 1970, 48, 181.
(33) Prust, J.; Most, K.; Muller, I.; Stasch, A.; Roesky, H. W.; Uson,
I. Eur. J. Inorg. Chem. 2001, 1613.

Article
Organometallics, Vol. 29, No. 21, 2010 4921
Table 3. Summary of Crystallographic Data for Compounds 8-14
8
9
10 OEt
3
2
11
empirical formula
formula wt
cryst syst
C
1165.07
monoclinic
64
H
104CaGa
2
N
8
C
64
H
104Ga
2
N
8
Sr
C
68
H
114BaGa
1336.45
orthorhombic
P2
2
N
8
O
C
61
H
93GaMgN
6
1212.61
monoclinic
C2/c
29.407(6)
14.031(3)
21.729(4)
90
131.56(3)
90
6709(2)
4
1.201
1.631
2576
0.15 ꢀ 0.12 ꢀ 0.10
3.13-25.00
11 084
1004.44
orthorhombic
Cc
22.756(5)
14.259(3)
21.172(4)
90
90
90
5894(2)
4
1.132
0.519
2176
0.30 ꢀ 0.25 ꢀ 0.20
2.14-30.00
48 551
space group
˚
1
P2 /c
1 1 1
2 2
a (A)
21.835(4)
14.049(3)
21.549(4)
90
95.48(3)
90
6580(2)
4
1.176
0.939
2504
18.122(4)
18.522(4)
21.842(4)
90
90
90
7331(3)
4
1.211
1.304
2816
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
3
˚
V (A )
Z
-
3
F(calcd) (g cm
)
-
1
μ (mm
F(000)
cryst size (mm)
)
0.40 ꢀ 0.15 ꢀ 0.10
2.92-26.00
24 843
0.25 ꢀ 0.20 ꢀ 0.18
2.92-25.35
13 382
θ range (deg)
no. of rflns collected
R
no. of unique rflns
goodness of fit on F
R1 indices (I > 2σ(I))b
wR2 indices (all data)
int
0.0613
12 905
1.031
0.0524
0.1417
0.0561
5872
1.039
0.0679
0.1942
0.0000
13 382
1.038
0.0314
0.0708
0.0276
13 672
1.028
0.0287
0.0745
2
a
c
d
1
2
13 0.25(hexane)
3
13
14
empirical formula
formula wt
cryst syst
C
707.78
32
H
52BrGaN
4
Zn
C
823.34
triclinic
P1
11.673(2)
17.925(4)
19.481(4)
104.83(3)
98.02(3)
91.53(3)
3893.5(13)
4
1.405
2.056
1666
0.25 ꢀ 0.12 ꢀ 0.10
2.60-24.98
24 058
33.5
H
55.5CdGaIN
4
C
801.80
32
H
52CdGaIN
4
55 4
C H77GaN Zn
929.30
monoclinic
monoclinic
/c
monoclinic
/n
space group
˚
P2
1
P2
1
1
P2 /n
a (A)
12.837(3)
13.316(3)
20.512(4)
90
92.83(3)
90
3502.2
4
1.342
2.620
1472
11.368(2)
14.249(3)
21.409(4)
90
95.88(3)
90
3449.9(12)
4
1.544
2.318
1616
11.971(2)
21.713(4)
20.586(4)
90
100.64(3)
90
5258.7(18)
4
1.174
1.005
1984
˚
b (A)
˚
c (A)
R (deg)
β (deg)
γ (deg)
3
˚
V (A )
Z
-
3
F(calcd) (g cm
)
-
1
μ (mm
F(000)
cryst size (mm)
)
0.35 ꢀ 0.25 ꢀ 0.22
2.92-27.00
14 440
0.08 ꢀ 0.06 ꢀ 0.04
2.56-24.88
11 543
0.20 ꢀ 0.15 ꢀ 0.12
2.55-28.00
22 159
θ range (deg)
no. of rflns collected
R
no. of unique rflns
goodness of fit on F
int
0.0363
7632
1.026
0.0418
0.1012
0.0463
13 171
1.025
0.0469
0.1038
0.0982
5960
1.038
0.0555
0.0288
12 677
1.028
0.0370
0.0887
2
a
R1 indices (I > 2σ(I))b
wR2 indices (all data)
0.0702
2 2
P
P
P
P
a
b
)). wR2(F ) = { w(|F
2
2
2 2 1/2
| } , where w is the weight given each
R1(F) = { (|F
reflection. Monomeric. Dimeric.
o
| - |F
c
|)/ |F
o
|} for reflections with F
o
> 4(σ(F
o
o
| - |F
c
| ) / w|F
o
c
d
overnight to yield yellow crystals of 12 (0.21 g, 60%). Mp:
1
extract was filtered, and the filtrate was stored at -30 °C
overnight to yield orange crystals of 13 (0.15 g, 38%). Mp:
1
24-126 °C dec. H NMR (300 MHz, C D , 300 K): δ 1.45
6
6
3
3
1
(
d, JHH=6.9 Hz, 12 H, CH(CH
H, CH(CH ), 1.65 (s, 12 H, N(CH
.94 (sept, JHH=6.9 Hz, 4 H, CH(CH
3
)
2
), 1.49 (d, JHH=6.9 Hz, 12
), 1.97 (s, 4 H, NCH ),
), 6.61 (s, 2 H, NCH),
.22-7.35 (m, 6 H, Ar-H). C{ H} NMR (100.6 MHz, C D ,
130-135 °C dec. H NMR (300 MHz, C
6
D
6
, 300 K): δ 1.43 (d,
3
3
3
3
)
2
3
)
2
2
J
HH=6.9 Hz, 12 H, CH(CH
CH(CH ), 1.65 (s, 12 H, N(CH
(sept, J = 6.9 Hz, 4 H, CH(CH ) ), 6.62 (s, 2 H, NCH),
3
)
2
), 1.48 (d, JHH=6.9 Hz, 12 H,
3
7
3
4
1
3
)
2
3
)
2
3
)
2
), 1.94 (s, 4 H, NCH ), 3.86
2
1
3
1
3
6
6
HH
3 2
1
3
1
00 K): δ 25.2 (CH(CH
7.6 (N(CH ), 56.2 (NCH
46.9 (Ar-C). IR (Nujol): 1657 w, 1557 w, 1377 m, 1359 m, 1287
3
)
2
), 25.4 (CH(CH
3
)
2
), 28.2 (CH(CH
3
)
2
),
7.22-7.33 (m, 6 H, Ar-H). C{ H} NMR (100.6 MHz, C
300 K): δ 25.0 (CH(CH ), 25.6 (CH(CH ), 28.3 (CH(CH
48.0 (N(CH ) ), 56.6 (NCH ), 122.9 (NCH), 123.0, 125.3, 145.6,
6 6
D ,
) ),
3 2
3
)
2
2
), 122.6 (NCH), 123.0, 124.9, 145.6,
3
)
2
3
)
2
3
2
2
-
1
w, 1260 m, 1101 m, 1023 m, 797 m, 760 m cm . MS (EI 70 eV;
m/z (%)): 706.1, (M , 4), 445.2 (Ga(DAB) , 15), 378.1
(DABH , 48), 333.3 (DAB - Pr , 100). Anal. Calcd for
C H BrGaN Zn: C, 54.30; H, 7.41; N, 7.92. Found: C,
147.0 (Ar-C). IR (Nujol): 1660 w, 1558 w, 1378 m, 1355 m, 1285
w, 1255 m, 1101 m, 1026 m, 793 m, 758 m cm . MS (EI 70 eV;
þ
þ
-1
þ
iþ
þ
þ
m/z (%)): 445.2 (Ga(DAB) , 100), 378.1 (DABH , 15), 333.3
(DAB - Pr , 53). Anal. Calcd for C H IGaN Cd: C, 47.93;
H, 6.54; N, 6.99. Found: C, 47.57; H, 6.48; N, 6.83.
iþ
3
2
52
4
32 52
4
5
3.92; H, 7.27; N, 7.77.
Preparation of [(tmeda)CdI{Ga(DAB)}] (13). To a solution of
Preparation of [(Nacnac)Zn{Ga(DAB)}] (14). A solution of
[K(tmeda)][:Ga(DAB)] (0.22 g, 0.36 mmol) in diethyl ether
(20 mL) was added over 5 min to a solution of [(Nacnac)Zn(μ-
[
CdI
was added [K(tmeda)][:Ga(DAB)] (0.30 g, 0.50 mmol) in THF
20 mL). The reaction mixture was warmed to ambient tem-
2
(TMEDA)] (0.24 g, 0.50 mmol) in THF (20 mL) at -80 °C
(
2 2 2
Br) Li(OEt ) ] (0.29 g, 0.36 mmol) in diethyl ether (20 mL)
perature over 4 h, whereupon volatiles were removed in vacuo.
The orange residue was extracted into hexane (30 mL), the
at -80 °C. The mixture was slowly warmed to room tempera-
ture, whereupon volatiles were removed in vacuo, leaving an

4
922 Organometallics, Vol. 29, No. 21, 2010
Bonello et al.
2
34
orange residue. This was extracted into hexane (35 mL) and the
extract filtered. The filtrate was stored at -30 °C overnight,
yielding orange crystals of 14 (0.17 g, 51%). Mp: 140-142 °C.
refined on F by full-matrix least squares (SHELX97 ) using all
unique data. All non-hydrogen atoms are anisotropic, with
hydrogen atoms (except the hydride ligands in the structure of
1
3
H NMR (300 MHz, C
6
D
6
, 300 K): δ 1.04 (d, JHH=6.9 Hz,
2 2
[Li(THF) {H Ga(DAB)}]) included in calculated positions (rid-
3
2 H, CH(CH ), 1.11 (d, JHH=6.9 Hz, 12 H, CH(CH
1
3
)
2
3
)
2
), 1.15
ing model). There are two crystallographically independent mole-
cules of 13 in the asymmetric unit of the monomeric structural
modification of the compound. There are no significant geometric
differences between them. The absolute structure parameters
for the crystal structures of 10 and 11 are -0.013(9) and 0.000(4),
respectively. Crystal data and details of data collections and
refinements are given in Table 3. CCDC numbers: 767655-767665.
3
d, JHH=6.9 Hz, 12 H, CH(CH ) ), 1.33 (d, JHH=6.9 Hz, 12
3
(
H, CH(CH ) ), 1.51 (s, 6 H, NCCH ), 3.04 (sept, JHH=6.9 Hz,
3 2
3
3
2
3
3
4
3 2 3 2
H, CH(CH ) ), 3.47 (sept, JHH=6.9 Hz, 4 H, CH(CH ) ), 5.02
(
s, 1 H, NCCH), 6.28 (s, 2 H, NCH), 7.05-7.30 (m, 12 H, Ar-H).
1
3
C NMR (100.6 MHz, C D , 300 K): δ 23.2, 23.8, 24.3, 24.8,
6
6
2
9
1
1
5.4 (4 ꢀ CH(CH ) , 1 ꢀ CCH ), 28.7, 28.8 (2 ꢀ CH(CH ) ),
3
2
3
3 2
7.9 (NCCH), 123.2 (NCH), 124.0, 124.2, 125.2, 125.8, 126.9,
41.8, 145.4, 148.5 (8 ꢀ br, Ar-C), 169.1 (CCH ). IR (Nujol):
656 w, 1519 m, 1380 m, 1317 m, 1261 m, 1179 m, 1159 m, 1099
3
Acknowledgment. We thank the Australian Research
Council (fellowships for CJ and AS). We also gratefully
acknowledge the EPSRC Mass Spectrometry Service,
Swansea, UK.
-1
m, 1022 m, 796 m, 758 m cm . MS (EI 70 eV; m/z (%)): 928.5
(
þ þ þ
M , 100), 481.3 ((Nacnac)Zn , 49), 445.2 (Ga(DAB) , 12),
þ
iþ
403.3 (NacnacH - CH , 9), 333.3 (DAB - Pr , 15). High-
resolution MS (EI; m/z): calcd for C H N GaZn, 926.4690;
3
5
5
77
4
found, 926.4688. Anal. Calcd for C55
8
H
77
N
4
GaZn: C, 71.08; H,
Supporting Information Available: CIF files giving crystal-
lographic data for 8-12, two structural modifications of 13, 14,
.35; N, 6.03. Found: C, 70.71; H, 8.16; N, 5.93.
X-ray Crystallography. Crystals of 8-12, two structural mod-
trans-[Ba{Ga(DAB)}
(OEt ], and [Li(THF)
diagrams for 8, 9, the monomeric structural modification of 13,
trans-[Ba{Ga(DAB)} (tmeda)(OEt ], [(Nacnac)CdI(μ-I)CdI-
(μ-I)Li(OEt ], and [Li(THF) {H Ga(DAB)}], a table giving
2
(tmeda)
2
], [(Nacnac)CdI(μ-I)CdI(μ-I)Li-
ifications of 13, 14, trans-[Ba{Ga(DAB)} (tmeda) ], [(Nacnac)-
2
)
3
2
{H Ga(DAB)}], figures giving ORTEP
2
2
2
CdI(μ-I)CdI(μ-I)Li(OEt
2
)
], and [Li(THF) {H
3 2
2
Ga(DAB)}] sui-
table for X-ray structural determination were mounted in silicone
oil. Crystallographic measurements were made using a Nonius
Kappa CCD diffractometer using a graphite monochromator
2
2 2
)
2
)
3
2
2
details of the crystallographic experiments and selected metrical
parameters for trans-[Ba{Ga(DAB)} (tmeda)(OEt ) ], [(Nacnac)-
˚
with Mo KR radiation (λ=0.710 73 A). The data were collected
at 123 K, and the structures were solved by direct methods and
2
2 2
CdI(μ-I)CdI(μ-I)Li(OEt
2
)
], and [Li(THF) {H Ga(DAB)}], and
3 2 2
2 2
text giving spectroscopic data for [Li(THF) {H Ga(DAB)}].
(34) Sheldrick, G. M. SHELX-97; University of G
Germany, 1997.
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