Synthesis and structural properties of the binary framework C-N compounds of Be, Mg, Al, and Tl

Article abstract of DOI:10.1006/jssc.2001.9192

The synthesis of crystalline Be(CN)₂ and Mg(CN)₂ has been demonstrated and X-ray diffraction studies indicate simple-cubic structures with four-coordinate metal atoms surrounded by an average of two N and two C atoms. The symmetry of Be(CN)₂ is Pn3m, a = 5.339(1) A, Z = 2. The symmetry of Mg(CN)₂ is also Pn3m, a = 6.122(1) A, Z = 2. A thallium cyanide with composition Tl(CN)₂ was prepared and was shown to have a similar simple-cubic structure with a = 6.660(1) A. On the basis of the X-ray diffraction pattern, IR spectra, and combustion analysis, this material is assigned the formula Tl^ITl^III(CN)₄. Crystalline Al(CN)₃ with simple-cubic structure has been prepared for the first time. Rietveld refinement indicated that the structure incorporates CN groups with orientational disorder in a Prussian-blue-like octahedral network. ²⁷Al NMR spectroscopy confirmed C,N disorder in cubic Al(CN)₃. The symmetry for Al(CN)₃ is Pm3m, a = 5.205(1) A.

Full text of DOI:10.1006/jssc.2001.9192

Journal of Solid State Chemistry 159, 244}250 (2001)
doi:10.1006/jssc.2001.9192, available online at http://www.idealibrary.com on
Synthesis and Structural Properties of the Binary Framework
C`N Compounds of Be, Mg, Al, and Tl
Darrick Williams, Brett Pleune, Kurt Leinenweber, and J. Kouvetakisꢀ
Department of Chemistry, Arizona State University, Tempe, Arizona 85287
Received January 16, 2001; in revised form March 12, 2001; accepted March 26, 2001
(5). This compound was obtained from the reaction of
The synthesis of crystalline Be(CN)2 and Mg(CN)2 has been
demonstrated and X-ray di4raction studies indicate simple-cubic
structures with four-coordinate metal atoms surrounded by an
average of two N and two C atoms. The symmetry of Be(CN)2 is
Pn3m, a ؍ 5.339(1) A, Z ؍ 2. The symmetry of Mg(CN)2 is also
Pn3m, a ؍ 6.122(1) A, Z ؍ 2. A thallium cyanide with composi-
tion Tl(CN)2 was prepared and was shown to have a similar
simple-cubic structure with a ؍ 6.660(1) A. On the basis of the
X-ray di4raction pattern, IR spectra, and combustion analysis,
this material is assigned the formula TlITlIII(CN)4. Crystalline
Al(CN)3 with simple-cubic structure has been prepared for the
5rst time. Rietveld re5nement indicated that the structure in-
corporates CN groups with orientational disorder in a Prussian-
blue-like octahedral network. 27Al NMR spectroscopy con5rmed
C,N disorder in cubic Al(CN)3. The symmetry for Al(CN)3 is
Pm3m, a ؍ 5.205(1) A. ( 2001 Academic Press
Be(CH ) with HCN and was only described as a polymeric
ꢂ ꢁ
colorless solid. Little is known about Mg(CN) , which was
ꢁ
purportedly obtained from the reaction of "nely divided
magnesium with HCN in liquid ammonia. This synthesis
was reported in a 1947 U.S. patent (6). In this study we
describe a practical synthetic method for crystalline
Mg(CN) and Be(CN) and report characterization of their
ꢁ
ꢁ
structures using powder X-ray di!raction. Both compounds
form diamond-like tetrahedral networks related to that of
Zn(CN) .
ꢁ
Synthesis of octahedrally coordinated main-group ana-
logs with composition M(CN) (where M is a group 13
ꢂ
element: B, Al, Ga, In, or Tl) that have large pores in the
structure is also of interest because these systems may pos-
ses interesting zeolitic and adsorption properties. Known
Key Words: main-group cyanides; Prussian blue; framework
structures.
examples of such materials include the binary Ga(CN) , and
ꢂ
In(CN) cyanides, which have Prussian-blue-type structures
ꢂ
that incorporate large cavities in the center of the simple-
cubic cell (7, 8). Very recently, crystalline B(CN) was iso-
ꢂ
INTRODUCTION
lated for the "rst time as a molecular Lewis acid}base
complex with bases such as N(CH ) and Si(CH ) CN (4).
ꢂ ꢂ
ꢂ
ꢂ ꢂ
Despite the great interest in cyanides in recent years (1) The existence of crystalline Al(CN) and Tl(CN) , however,
ꢂ
there are still some surprising gaps of knowledge concerning has not been established to date. In the current study we
main-group element binary cyanides, including those of focus on preparation and structural characterization of the
beryllium, magnesium, aluminum, and thallium. Recent missing Al(CN) and related Tl compounds to complete the
ꢂ
work on development of superhard materials and related entire family of binary M(CN) compounds of group 13
ꢂ
refractory ceramics has stimulated interest in synthesis of elements. Previous attempts to prepare aluminum cyanide
cyanides particularly those that are isoelectronic to dia- have produced only uncharacterized materials with com-
mond and incorporate light elements such as Li, Be, B, C, N, positions purportedly close to the desired Al(CN) product
ꢂ
Mg, Al, and Si (2}4). The stoichiometric cyanides Be(CN)
(9, 10). TlCN is the only known and well characterized
ꢁ
and Mg(CN) have an average number of four valence cyano compound of Tl and has a disordered CsCl-type
ꢁ
electrons per atom and are attractive precursors for high- structure (11).
pressure synthesis of dense tetrahedral materials of the
same stoichiometry that have properties related to those of
diamond.
RESULTS AND DISCUSSION
A previously reported cyanide of beryllium with composi-
tion close to Be(CN) was not characterized to any extent
The synthesis of M(CN) (M"Be, Mg) utilizes a
ꢁ
ꢁ
common reagent, (CH ) SiCN, which undergoes metathesis
ꢂ ꢂ
ꢀ To whom correspondence should be addressed.
with MCl to produce the desired composition at low
ꢁ
244
0022-4596/01 $35.00
Copyright ( 2001 by Academic Press
All rights of reproduction in any form reserved.

PROPERTIES OF C}N COMPOUNDS OF Be, Mg, Al, AND Tl
245
temperatures in nonaqueous solvents (Eq. [1]):
MCl #2(CH ) SiCNPM(CN) #2(CH ) SiCl
ꢂ ꢂ ꢂ ꢂ
ꢁ
ꢁ
M"Be, Mg.
[1]
Be(CN) was initially amorphous and an annealing step at
ꢁ
5003C was necessary to obtain crystalline material. The
preparation of crystalline Mg(CN) also required a brief
ꢁ
annealing step at 3753C. Pure Be(CN) is a colorless, air-
ꢁ
stable solid which is thermally stable up to 7003C. Mg(CN)
is also colorless and highly moisture sensitive. The IR spec-
ꢁ
trum of Be(CN) is very simple and shows only two peaks:
ꢁ
l C}N at 2233 cm\ꢀ and l M}CN at 756 cm\ꢀ. The corre-
sponding peaks for Mg(CN) appear at 2197 and 492 cm\ꢀ,
ꢁ
respectively. The absence of any vibrational modes above
3000 cm\ꢀ in the IR spectra of both compounds indicates
that they do not contain any CH, NH, or OH contamination.
FIG. 2. X-ray di!raction pro"le "t for Mg(CN) . The data shown as
# and the tick marks are the Bragg positions. The solid line is the
calculated pro"le and the di!erence curve is at the bottom on the same
ꢁ
The X-ray di!raction pattern of Be(CN) revealed
scale.
ꢁ
a simple-cubic structure with a lattice parameter a"
5.339(1) A. Rietveld re"nement using a model similar to that
of Zn(CN) with Pn3m symmetry gave an average Be}(C, N) Mg) tetrahedra are joined at the vertices by C}N bonds.
ꢁ
bond length of 1.718(1) A and a C}N bond length of This is in contrast to the ordered arrangement observed in
1.187(1) A, which compare well with reported values (4). the structurally related LiB(CN) material, which has the Li
ꢃ
X-ray di!raction shows that Mg(CN) has the same simple- atoms exclusively bonded to N atoms and the B atoms
ꢁ
cubic structure with a"6.122 (1) A. The structure was re- bonded to C atoms to form two interpenetrating lattices of
"ned in Pn3m and the bond lengths of C}N and Mg}(C,N) LiN and BC tetrahedra joined by C}N bonds (4). A sketch
ꢃ
ꢃ
were found to be 1.085(7) and 2.108(4) A, respectively. The of the structure of Mg(CN) and Be(CN) is shown in Fig. 3.
ꢁ
ꢂ
ꢁ
observed and calculated pro"les for Be(CN) and Mg(CN)
The synthesis of Al(CN) was accomplished via a meta-
ꢁ
ꢁ
are shown in Figs. 1 and 2, respectively. Atomic positions, thesis reaction involving interaction between of LiAlCl and
ꢃ
displacement factors, and a summary of Rietveld re"nement (CH ) SiCN. The reaction proceeds essentially quantitat-
ꢂ ꢂ
for these compounds are shown in Tables 1 and 2, respec- ively according to
tively. There are no ordering re#ections in the X-ray pat-
terns of either compound (for instance, (100) is absent in
LiAlCl #3(CH ) SiCNPAl(CN) #3(CH ) SiCl#LiCl.
ꢃ
ꢂ ꢂ
ꢂ
ꢂ ꢂ
both patterns). Consequently, disorder of the C}N groups
[2]
results in an average structure in which M(C,N) (M"Be,
ꢃ
Removal of the volatiles from the reaction mixture gave
a colorless residue that was extracted with THF to remove
LiCl and yield the desired cyanide product. The compound
TABLE 1
Atomic Positions and Displacement Factors (U) for
Be(CN)2, and Mg(CN)2 with Pn3m Symmetry and Al(CN)3
with Pm3m Symmetry
Atoms
Wyc.
x
y
z
;(Aꢁ)
Be
(C, N)
Mg
(C, N)
Al
(C, N)
2a
8e
2a
8e
1a
6e
0.25
0.25
0.25
0.064(3)
0.4358(1) 0.4358(1) 0.4358(1) 0.103(3)
0.25 0.25 0.25 0.104(3)
0.4462(3) 0.4462(3) 0.4462(3) 0.101(3)
0.0
0.0
0.0
0.0
0.0423(1)
0.0399(1)
FIG. 1. X-ray powder di!raction pro"le for Be(CN) . The top line is
0.3882(4) 0.0
ꢁ
the experimental data and the bottom one is the di!erence between the
experimental and calculated data on the same scale.
Note. The C, N positions are occupied by 0.5 C and 0.5 N.

246
WILLIAMS ET AL.
TABLE 2
Summary of Rietveld Re5nement for Mg(CN)2, Be(CN)2,
and Al(CN)3
Mg(CN)
Be(CN)
Al(CN)
ꢁ
ꢁ
ꢂ
Space group
Pn3m
Pn3m
Pm3m
Unit cell parameter (A)
Volume (Aꢂ)
No. of re#ections
a"6.122(1)
229.45(1)
22
a"5.339(1)
151.2(1)
46
a"5.205(3)
141.09(24)
46
No. of re"ned parameters 14
15
17
sꢁ
1.82
4.72
5.99
6.87
4.54
6.64
2.485
3.30
4.36
R
R
ꢀ
ꢁꢀ
was initially amorphous but it crystallized upon heating at
temperatures in excess of 4003C. The pure material is
a colorless solid, stable in air, and insoluble in polar organic
solvents. The IR spectrum reveals strong absorptions at
2220 and 530 cm\ꢀ, corresponding to l C}N and l Al}
(C}N), respectively. These values compare well with the
corresponding values of the related aluminum cyanide
[(CH ) Al(CN)] which were observed at 2224 and
ꢂ ꢁ
ꢃ
510 cm\ꢀ, respectively (5). The X-ray di!raction pattern
(Fig. 4) revealed a simple cubic unit cell with Pm3m sym-
metry and a"5.205(1) A. Rietveld re"nement indicated
a disordered structure with respect to the orientation of the
C, N ligands. The Al atoms in the structure occupy the cell
corners and are octahedrally coordinated by C, N ligands,
which are aligned at the cell edges (Fig. 5). The C}N bond
length was found to be 1.164(5) A, a value normal for metal
cyanides, and the Al}(C,N) distance is 2.021(2) A. A sum-
mary of the crystallographic data for Al(CN) is shown in
ꢂ
Tables 1 and 2.
Further evidence for the C,N static disorder in Al(CN) is
ꢂ
provided by the solid-state ꢁꢄAl NMR spectrum of the
compound which reveals a multiplet consisting of at least
seven narrow and closely spaced peaks as shown in Fig. 6.
This pattern indicates the presence of seven possible Al sites,
which are likely to be created by the orientational static
disorder of bridging cyanides in the structure. The seven site
possibilities are (Al)C6, (Al)C5N, (Al)C4N2, (Al)C3N3,
(Al)C2N4, (Al)CN5, and (Al)N6 and correspond to the num-
ber of possible ways of arranging the C and N atoms in an
octahedron. We speculate that the resonances with peak
maxima at !37.95, !39.59, !41.46, !43.81, !47.32,
!50.84, and !54.35 ppm correspond to those sites, respec-
tively. As illustrated in the ꢁꢄAl NMR spectrum in Fig. 6 the
resonances down"eld are better resolved than those up"eld;
i.e., the peak separation increases as one moves from Al sites
predominately surrounded by C (down"eld) to those sur-
rounded by N (up"eld). The ꢁꢄAl NMR spectrum is consis-
FIG. 3. (Top) Schematic of structure of M(CN) (M"Be, Mg) shown
ꢁ
as M(C,N) tetrahedra. (Bottom) Unit cell of M(CN) .
ꢃ
ꢁ
sible distributions of C and N about Cd in a Cd(C,N)
ꢃ
ꢁ
tetrahedron (12). The CdC site in the disordered Cd(CN)
ꢃ
structure was assigned the largest down"eld shift and the
CdN the smallest. The separation between peaks also
ꢃ
decreases down"eld in the NMR spectrum.
The synthesis of the tricyanide of thallium was attempted
by reaction of TlCl with a stoichiometric amount of
ꢂ
(CH ) SiCN in ether. A colorless solid was isolated from
ꢂ ꢂ
this reaction and was identi"ed by IR spectroscopy to be
a cyanide. The vibrational spectrum showed a broad ab-
sorption at 392 cm\ꢀ, corresponding to l Tl}(C,N), and two
tent with the reported ꢀꢂCd NMR spectrum of Cd(CN) ,
ꢁ
which shows "ve resonances corresponding to the "ve pos-

PROPERTIES OF C}N COMPOUNDS OF Be, Mg, Al, AND Tl
247
FIG. 4. X-ray di!raction pro"le "t for Al(CN) . The top line is the experimental data and the bottom one is the di!erence between the experimental
ꢂ
and calculated data on the same scale.
closely spaced and sharp C}N absorptions at 2209 and be non bridging, shows an increase in C}N stretching
2198 cm\ꢀ. A comparison of these stretches with that of frequency. Since bridging C}N groups are known to exhibit
(CH ) TlCN (2100 cm\ꢀ) (5), in which C}N appears to higher stretching frequencies (7, 13), we attribute both of the
ꢂ ꢁ
2209 and 2198 cm\ꢀ frequencies to stretching modes of
bridging C}N groups. The absence of any absorptions
above 3000 cm\ꢀ is indicative that the solid did not contain
any CH, NH, and OH impurity groups. Elemental analysis
for C, H, N, and Cl con"rmed that the material was free of
H and Cl impurities and also indicated a composition close
to TlC N .
ꢁ ꢁ
The X-ray di!raction pattern was very simple and sugges-
ted single-phase material. All di!raction data were indexed
FIG. 5. Structure of Al(CN) shown as interconnected Al(C,N) oc-
FIG. 6. Solid-state (magic angle spinning) ꢁꢄAl spectrum of Al(CN)
illustrating seven resonances. These suggest that Al in the structure is in
ꢂ
ꢅ
ꢂ
tahedra. The Al atoms, in the centers of the octahedra, are surrounded by
six (C,N) atoms (small spheres), which are shown to be linked by lines seven di!erent environments of (Al)C6, (Al)C5N, (Al)C4N2, (Al)C3N3,
representing C}N bonds. (Al)C2N4, (Al)CN5, and (Al)N6.

248
WILLIAMS ET AL.
be a lower bond order and thus a lower stretching frequency
TABLE 3
for the C}N bond in Tlꢀ>}(C}N) relative to that in Tlꢂ>}
Observed and Calculated d spacings (A) and Relative Intensities
in the X-ray Di4raction Powder Pattern for Tl(CN)2
(C}N). The IR spectrum of Tl(CN) also correlates well with
ꢁ
the IR spectra of well-known transition metal cyanides with
cations in two oxidation states. Such compounds have been
shown in previous studies to exhibit two stretching C}N
absorptions (14). It is worth noting that the tetrahedral
h
k
l
d
I/I
ꢂ ꢂ"ꢃ
d
I/I
ꢂ #!ꢄ#
ꢂ"ꢃ
#!ꢄ#
1
1
1
2
2
2
2
2
3
3
3
2
3
3
3
4
3
4
0
1
1
0
1
1
2
2
1
1
1
2
2
2
3
2
3
2
0
0
1
0
0
1
0
1
0
1
1
2
0
1
0
0
2
2
6.600
4.666
3.810
3.300
2.970
2.694
2.333
2.220
2.087
2.000
2.000
1.905
1.84
(1
4.662
3.282
100.0
15
100.0
2
coordination observed in Tl'Tl''' (CN) is not common for
ꢃ
12
(1
41
the oxidation state Tlꢀ>, although there are many examples
of the oxidation state Tlꢂ> in tetrahedral coordination (15).
Another point to make is that the lattice parameter of
2.687
2.328
43
19
17
Tl'Tl'''(CN) [6.660(1) A] is one of the largest observed in
(1
(17
(1
(1
4
(1
20
8
ꢃ
binary Zn(CN) structure types.
2.087
1.903
14
9
ꢁ
A previously reported material with formula close to
Tl(CN) was not characterized to any extent. The synthesis
ꢁ
was carried out in aqueous media and the material was
described to be stable in air. The anhydrous cyanide
1.761
1.551
1.477
1.406
1.356
19
8
7
8
6
1.764
1.555
1.476
1.407
1.347
Tl(CN) prepared using our method interacts readily with
ꢁ
20
3
3
air and moisture. X-ray di!raction of samples exposed to air
show conversion of the compound into a pollycrystalline
powder of an unknown structure. Anhydrous Tl(CN) also
ꢁ
decomposes readily to TlCN and cyanogen gas (see Eq. [3])
with mild heating either under static or dynamic vacuum
conditions.
Note. The small C, N contribution to I/I calc has been included in the
ꢂ
calculation.
Tl'''Tl'(CN) P2TlCN#(CN) .
[3]
ꢃ
ꢁ
by using a primitive cubic cell with a"6.660(1) A. The
results were consistent with a tetrahedral structure of Pn3m This facile elimination of CN resulting in reduction of Tlꢂ>
symmetry similar to that observed in the previously de- to form the more stable oxidation state Tlꢀ> indicates that
scribed Be(CN) and Mg(CN) compounds. The observed a solid-state Tl(CN) cyanide with a Prussian-blue structure
ꢁ
ꢁ
ꢂ
and calculated di!raction patterns for this topology are in analogous to that of Al(CN) will be very di$cult to isolate
ꢂ
good agreement, and the calculated and observed intensities as a stable phase at room temperature. Thallium (III) cyano
of the X-ray lines are compared in Table 3. The X-ray complexes, however, with the general formula Tl(CN)(ꢂ\L)>,
L
analysis clearly points to a structure that consists of where n"2, 3, and 4, are known to exist in solution and
Tl(C,N) tetrahedra joined at the vertices by bridging C}N their properties have been extensively investigated in recent
ꢃ
groups to form a network that is isomorphic and composi- studies (16, 17). This leads us to believe that stoichiometric
tionally analogous to the disordered Cd(CN) phase of Tl(CN) might also exist as a soluble intermediate in route
ꢁ
ꢂ
Pn3m symmetry. However, because of the high contrast to Tl(CN) , according to our synthetic procedure sum-
ꢁ
between Tl and (C, N) it is not possible to tell whether the marized below:
C, N atoms are ordered or disordered in this material. Based
on the structural and the combustion analysis results we
TlCl #3(CH ) SiCNP&&Tl(CN) ''#3(CH ) SiCl [4]
ꢂ
ꢂ ꢂ ꢂ ꢂ ꢂ
conclude that this material has a Tl(CN) empirical formula
ꢁ
and should incorporate the Tl cations in two di!erent oxi-
&&Tl(CN) ''PTl(CN) #1/2(CN) .
[5]
ꢂ
ꢁ
ꢁ
dation states, i.e., Tl'Tl''' (CN) .
ꢃ
The existence of Tl>ꢂ and Tl>ꢀ cations in the lattice is We attempted to isolated Tl(CN) as a Lewis acid}base
ꢂ
also shown by the presence of the two C}N stretching complex with a wide variety of Lewis bases but our e!orts
modes at 2209 and 2198 cm\ꢀ in the IR spectrum, the were unsuccessful.
higher frequency corresponding to Tlꢂ>}(C}N) and the
lower to Tlꢀ>}(C}N) stretching modes. This assignment can
be rationalized by the concept of backdonation of electron
density from the metal into the n* (antibonding) orbital of
SUMMARY
The simple compounds Al(CN) , Be(CN) , and Mg(CN)
ꢂ
ꢁ
ꢁ
the C}N ligand. Such backdonation would tend to be sub- have been prepared by use of a novel synthetic method, and
stantially higher from the less positive Tlꢀ> than from the their structures have been determined by X-ray powder
more positive Tlꢂ> metal center. The net result should then di!raction. Al(CN) has an octahedral Prussian-blue-type
ꢂ

PROPERTIES OF C}N COMPOUNDS OF Be, Mg, Al, AND Tl
249
ꢁꢄ
structure and it is shown to have C, N disorder by Al
Synthesis of Al(CN) . (CH ) SiCN (2.227 g, 0.0225 mol)
ꢂ
ꢂ ꢂ
MAS-NMR spectroscopy. Be(CN) and Mg(CN) form dia- was added dropwise to a stirring solution of LiAlCl (0.5 g,
ꢁ
ꢁ
ꢃ
mond-like tetrahedral networks with twofold interpenetra- 0.005 mol) in 30 mL of dry ether at !783C. The reaction
tion similar to that observed in the classical Zn(CN) and was warmed to 223C and a colorless precipitate was im-
ꢁ
Cd(CN) compounds. The search for Tl(CN) , analogous to mediately formed. After stirring for an additional 12 h the
ꢁ
ꢂ
Al(CN) , has led to the synthesis of the mixed-oxidation precipitate was collected, dried under vacuum, and exam-
ꢂ
'
'''
phase Tl Tl (CN) . X-ray powder di!raction suggests that ined by powder X-ray di!raction. The powder di!raction
ꢃ
this material is isostructural to Zn(CN) .
pattern revealed crystalline LiCl and also indicated the
presence of an amorphous component that was identi"ed by
ꢁ
\ꢀ
EXPERIMENTAL
IR spectroscopy to be a cyanide (l C}N 2220 cm ). The
product was annealed at 4003C under nitrogen for 18 h to
\ꢀ
General considerations. All preparations were per- yield crystalline Al(CN) (l C}N 2220 cm ) and LiCl. Pure
ꢂ
formed under prepuri"ed N using standard Schlenk and Al(CN) was isolated by extraction of LiCl from the mixture
drybox techniques. Solvents were dried and distilled prior to with warm H O or tetrahydrofuran. A structure determina-
ꢁ
ꢂ
ꢁ
use. The FTIR spectra were recorded on a Nicolet-Magna- tion summary is shown in Table 2.
ꢁꢄ
IR 550 spectrometer from Nujol and #uorolube mulls. Al
NMR spectra were recorded on a Varian Unity 500 spec-
trometer and were referenced to the resonance of a 1 M
Synthesis of ¹l(CN) . An ether solution of (CH ) SiCN
ꢁ
ꢂ ꢂ
(1.851 g, 0.0187 mol) was added dropwise to a stirring solu-
solution of AlCl . Samples for X-ray powder di!raction
tion of TlCl (1.21 g, 0.0060 mmol) in 20 mL of ether at 03C.
ꢂ
ꢂ
were loaded in an environmental cell with a Kapton win-
The solution was then heated under re#ux for 24 h, after
dow and the data were collected on a Siemens D5000 X-ray
di!ractometer using CuKa radiation. The re"ned data con-
sisted of a single scan with 0.023 steps at a rate of 0.673 per
minute. Re"nement of the data was performed using the
Generalized Structural Analysis System (GSAS), a Rietveld
which time its total volume was reduced to 15 mL, and it
was stored for several days at !53C. During this time
a colorless solid formed. This material was isolated by
"ltration and it was washed with a hot hexane/benzene
solution. It was dried for several hours under vacuum. Calcd
re"nement code (18). (CH ) SiCN (Aldrich 98%) was
for Tl(CN) : C, 9.4; H, 0; N, 12.2; Cl, 0. Found C, 10.5; H,
ꢂ ꢂ
ꢁ
puri"ed by distillation prior to use. BeCl (Cerac 99.5%),
(0.05; N, 11.0; Cl, 0.80.
ꢁ
MgCl (Aldrich 98%), AlCl (Aldrich 99.98%), and TlCl
(Alfa) were used as received.
ꢁ
ꢂ
ꢂ
ACKNOWLEDGMENTS
Synthesis of Be(CN) . (CH ) SiCN (2.9 g, 0.029 mol)
ꢁ
ꢂ ꢂ
was added dropwise to a stirring suspension of BeCl (1.0 g,
ꢁ
We thank the National Science Foundation (DMR-9902417) and the
Army Research O$ce (ARO) for "nancial support. One of us (DW)
acknowledges support from NSF Grant DMR 9458047.
0.013 mol) in butyl ether (30 mL) at !203C. The mixture
was warmed to room temperature, stirred for 18 h, then
heated to 1003C for an additional 12 h. The mixture was
"ltered and the resulting solid was dried and then heated to
5003C for 48 h under vacuum to yield a colorless solid.
REFERENCES
\ꢀ
Yield: 0.554 g (70%). IR (Nujol, cm ): 2233 (m), 756 (s, br).
The observed and calculated X-ray di!raction patterns of
1. K. R. Dunbar and R. A. Heinz, Prog. Inorg. Chem. 45, (1997).
2. C. M. Sung and M. Sung, Mater. Chem. Phys. 1, 47 (1996).
3. V. M. Badding, Adv. Mater. 9, 877 (1977).
Be(CN) are shown in Fig. 1. A structure determination
ꢁ
summary is shown in Table 2.
4. D. Williams, B. Pleune, J. Kouvetakis, M. D. Williams, and R. A.
Anderesen, J. Am. Chem. Soc. 122, 7735 (2000).
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SSSR Ser. Chim. 2826 (1968).
Synthesis of Mg(CN) . (CH ) SiCN (1.3 g, 0.013 mol)
ꢁ
ꢂ ꢂ
was added dropwise to a stirring suspension of MgCl
ꢁ
(0.5 g, 0.005 mol) in butyl ether (30 mL) at room temper-
ature. The mixture was re#uxed for 18 h and "ltered, and
the resulting solid was dried in vacuum. The product was
combined with (CH ) SiCN (1.3 g, 0.013 mol) and the mix-
ꢂ ꢂ
ture was heated in a closed Schlenk tube under an atmo-
sphere of nitrogen at 2003C for about 12 h. The resulting 10. G. Wittig and G. Z. Ra!, Naturforscher 6B, 225 (1951).
11. T. Matsuo, M. Sugisaki, H. Suga, and S. Seki, Z. Anorg. Allgem. Chem.
material was annealed at 3753C for 4 h to yield Mg(CN) as
ꢁ
344, 86 (1966).
\ꢀ
a colorless solid. Yield: 0.240 g (63%). IR (nujol, cm ): 2197
12. N. Nishikiori, C. I. Ratcli!e, and J. A. Ripmeester, Can. J. Chem. 68,
2270 (1990).
13. D. A. Haim and A. Wilmarth, J. Inorg. Nucl. Chem. 21, 33 (1961).
14. N. S. Ghosh, J. Inorg. Nucl. Chem. 36, 2465 (1974).
(m), 492 (s, br). The observed and calculated X-ray di!rac-
tion patterns of Mg(CN) are shown in Fig. 2, and a struc-
ꢁ
ture determination summary is shown in Table 2.

250
WILLIAMS ET AL.
15. N. N. Greenwood and A. Earnshaw, &&Chemistry of the Elements.'' 17. I. Banyai, J. Cgaser, and J. Losonczi, Inorg. Chem. 36, 5900 (1997).
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18. A. C. Larson and R. B. Von Dreele, &&GSAS Generalized Structure
Analysis System,'' LANSCE, MS-H805. Manual Lujan Neutron
Scattering Center, Los Alamos, NM, 1989.