Pentafluorosulfanylnitramide salts

Article abstract of DOI:10.1021/ic991281i

The synthesis and properties of a new class of inorganic salts, named pentafluorosulfanylnitramide salts (or pentafluorosulfanylnitraminic acid salts) [Z⁺SF₅NNO₂^-], are described. A number of SF₅-nitramide salts (Z⁺SF₅NNO₂^-) were successfully prepared via nucleophilic displacements from carbamates and/or ion exchange techniques, but some salts [M(SF₅NNO₂)(x); M = Li, Mg, Al] decomposed during isolation procedures and appear to be unstable in the solid state. Single-crystal X-ray diffraction was used to fully characterize the Z⁺SF₅NNO₂^-, and their properties/structures are compared with those of the corresponding dinitramide salts (or dinitraminic acid salts), Z⁺N(NO₂)₂^-. X-ray crystallography revealed major structural differences between N(NO₂)₂^- and SF₅N(NO₂)^- salts concerning the N-N distances and the angles subtended at the central nitrogen atom. In the N(NO₂)₂^- salts, there are two nonequivalent N-N (average lengths 1.372(2) and 1.354(2) A) distances and an average N-N-N angle of 115.8(3)°(falls between sp³ and sp² hybridization). In the SF₅NNO₂^- salts, the average N-N distance is much shorter, 1.308(9) A, and the average N-N-S angle is 120.0(5)°(closely fits sp² hybridization). The SF₅NNO₂^- salts show a remarkable metrical similarity for the SF₅ moiety in all structures, indicating a lack of sensitivity to its steric and electronic environment. This is in marked contrast to N(NO₂)₂^-, where there is a wide variation in conformations adopted by these anions which can be related to their environment.

Full text of DOI:10.1021/ic991281i

Inorg. Chem. 2000, 39, 843-850
843
Pentafluorosulfanylnitramide Salts
Michael E. Sitzmann,*, Richard Gilardi,* Ray J. Butcher, William M. Koppes,
1a
,1b
1c
1a
Alfred G. Stern,1a Joseph S. Thrasher, Nirupam J. Trivedi, and Zhen-Yu Yang
1d
1a
1d
Naval Surface Warfare Center, Indian Head Division, Indian Head, Maryland 20640, Laboratory for the
Structure of Matter, Naval Research Laboratory, Washington, D.C. 20375, Department of Chemistry,
Howard University, Washington, D.C. 20059, and Department of Chemistry, The University of
Alabama, Tuscaloosa, Alabama 35487
ReceiVed NoVember 2, 1999
The synthesis and properties of a new class of inorganic salts, named pentafluorosulfanylnitramide salts (or
+
-
pentafluorosulfanylnitraminic acid salts) [Z SF5NNO2 ], are described. A number of SF5-nitramide salts
(
+
-
Z SF5NNO2 ) were successfully prepared via nucleophilic displacements from carbamates and/or ion exchange
techniques, but some salts [M(SF5NNO2)x; M ) Li, Mg, Al] decomposed during isolation procedures and appear
+
-
to be unstable in the solid state. Single-crystal X-ray diffraction was used to fully characterize the Z SF5NNO2 ,
and their properties/structures are compared with those of the corresponding dinitramide salts (or dinitraminic
+
-
-
acid salts), Z N(NO2)2 . X-ray crystallography revealed major structural differences between N(NO2)2 and
-
SF5N(NO2) salts concerning the N-N distances and the angles subtended at the central nitrogen atom. In the
-
N(NO2)2 salts, there are two nonequivalent N-N (average lengths 1.372(2) and 1.354(2) Å) distances and an
3
2
-
average N-N-N angle of 115.8(3)° (falls between sp and sp hybridization). In the SF5NNO2 salts, the average
2
N-N distance is much shorter, 1.308(9) Å, and the average N-N-S angle is 120.0(5)° (closely fits sp
-
hybridization). The SF5NNO2 salts show a remarkable metrical similarity for the SF5 moiety in all structures,
-
indicating a lack of sensitivity to its steric and electronic environment. This is in marked contrast to N(NO2)2 ,
where there is a wide variation in conformations adopted by these anions which can be related to their environment.
Introduction
physical and chemical property changes that occur in various
materials with the incorporation of an SF5 group. Previous
investigations include a demonstration that the SF5 group can
3
2
Recent articles report investigations in the U.S.A. and Russia
concerning the syntheses and crystal structures of dinitramide
act as an oxidizing moiety (producing HF and OdCdS as
+
-
salts, Z N(NO2)2 [salts of dinitraminic acid, HN(NO2)2].
3
c
+
-
oxidation products), suggesting that Z SF5NNO2 may be
useful as oxidizer ingredients.
+
-
Ammonium dinitramide, NH4 N(NO2)2 , is of special interest
as a non-chlorine-containing oxidizer in rocket propellants and
offers significant advantages over currently used oxidizers such
as ammonium perchlorate, especially from an environmental
standpoint, given that chlorine-containing combustion products
are generally not environmentally benign materials.
Dinitramide salt analogs, Z N(X)(NO2) , in which a nitro
group in a dinitramide salt is substituted by group X, are being
investigated in an effort to provide salts with improved physical
and energetic properties (e.g., increased density, oxidant level,
etc.). This report, concerning the syntheses/properties/crystal
Results and Discussion
+
-
Syntheses. The synthetic strategy toward Z SF5NNO2 (1)
was to identify and synthesize SF5-containing precursors (SF5-
+
-
+
-
structures of pentafluorosulfanylnitramide salts (Z SF5NNO2 ;
X ) SF5), describes a continuation of our research in the area
of SF5 chemistry, which has included the synthesis of SF5
materials/intermediates, as well as the determination of the
NHR1) which potentially could be nitrated to produce SF5-
NNO2R1 and from which R1 could later be removed to produce
the desired salt. Groups R1 under consideration included
COOCMe3 and CMe3 (removal under acidic conditions) and
COOCH2CH2SiMe3 (removal by treatment with fluoride).4
Also under consideration, as a potential synthesis route to 1,
was a method analogous to that developed at NSWC for
(
1) (a) NSWC, Indian Head Division. (b) Naval Research Laboratory.
c) Howard University. (d) University of Alabama.
2) (a) Bottaro, J. C.; Penwell, P. E.; Schmitt, R. J. J. Am. Chem. Soc.
997, 119, 9405 and references therein. (b) Trammell, S.; Goodson,
(
(
+
-
+
-
NH4 N(NO2)2 . This method for NH4 N(NO2)2 generates
1
P. A.; Sullivan, B. P. Inorg. Chem. 1996, 35, 1421. (c) Martin, A.;
Pinkerton, A. A.; Gilardi, R. D.; Bottaro, J. C. Acta Crystallogr. 1997,
B53, 504. (d) Gilardi, R.; Flippen-Anderson, J.; George, C.; Butcher,
R. J. J. Am. Chem. Soc. 1997, 119, 9411. (e) Part 2: Gilardi, R.;
Butcher, R. J. J. Chem. Crystallography 1998, 28, 95. (f) Part 3:
Gilardi, R.; Butcher, R. J. J. Chem. Crystallography 1998, 28, 163.
(3) (a) Thrasher, J. S.; Howell, J. L.; Clifford, A. F. Chem. Ber. 1984,
117, 1707. (b) Thrasher, J. S.; Clifford, A. F. J. Fluorine Chem. 1982,
19, 411. (c) Sitzmann, M. E.; Gilligan, W. H.; Ornellas, D. L.;
Thrasher, J. S. J. Energ. Mater., 1990, 8, 352. (d) Sitzmann, M. E. J.
Fluorine Chem. 1991, 52, 195. (e) Sitzmann, M. E.; Gilardi, R. D. J.
Fluorine Chem. 1993, 63, 203. (f) Sitzmann, M. E. J. Fluorine Chem.
1995, 70, 31.
(
g) Part 4: Gilardi, R.; Butcher, R. J. J. Chem. Crystallography 1998,
8, 105. (h) Part 5: Gilardi, R.; Butcher, R. J. J. Chem. Crystal-
2
lography 1998, 28, 673. (i) Parts 6 and 7: Gilardi, R.; Butcher, R. J.
Manuscripts in preparation.
(4) Similar to the preparation of dinitramide salts from (NO2)2NCH2CH2-
SiMe3 as described in ref 2a.
1
0.1021/ic991281i CCC: $19.00 © 2000 American Chemical Society
Published on Web 02/21/2000

844 Inorganic Chemistry, Vol. 39, No. 4, 2000
Sitzmann et al.
the dinitramide salt via a displacement reaction from dinitro-
carbamate [(NO2)2NCO2Et]. For the analogous synthesis of 1,
the required SF5NNO2CO2R2 are available via nitration of SF5-
NHCO2R2, obtained by condensation of SF5NdCdO with R2-
OH.3d The particular SF5NNO2CO2R2 chosen for the synthesis
of 1 was N-(pentafluorosulfanyl)-N-nitro octyl carbamate (2)
in its decomposition. Similarly, the Mg and Al(SF5NNO2)x salts
also decomposed during attempts to isolate them from their
aqueous solutions. (A description of the attempts to prepare and
isolate these salts is given in the Experimental Section).
Stabilities of M (SF5NNO2)x. The Li, Mg, and Al(SF5NNO2)x
salts appear to be inherently unstable in the solid state. A
possible rationale for this instability is that preferential metal
complexation with oxygen vs nitrogen in these salts results in
loss of resonance stabilization, leading to decomposition.
Another potential driving force for the instability of the Li,
Mg, and Al(SF5NNO2)x salts is the precipitation of insoluble
5
(see eq 1), mainly because of its ease of handling (low volatility).
7
fluoride salts from concentrated solutions of these SF5-nitramide
salts.
6
Characterization of 1. (a) 19F NMR Spectral Data. The
The first SF5-nitramide salt synthesized via 2 was 1a (eq 2),
6
19
which was then employed to prepare 1b via ion exchange.
However, an improved synthesis of 1b, directly from 2, has
now been developed (eq 3).
F NMR spectra of 1 exhibit only a doublet and a quintet, an
absorption pattern that is characteristic of the SF5 group (four
F syn and one F anti to the NNO2 group).
(
b) IR Spectral Data. The infrared spectra of 1 contain two
-
1
strong peaks of about equal intensity in the 1400-1300 cm
-
region (characteristic of R-N-NO2 ). In addition, the IR
-1
spectra contain strong absorptions in the 900-800 cm region,
which is characteristic of the SF5 group.
(c) Physical Properties. The melting points and densities of
1
are listed in Table 1 and are compared with data for
+
-
Z N(NO2)2 . It is seen that compounds 1 are significantly more
dense than the corresponding Z N(NO2)2 but are less thermally
stable.
We also had interest in metal SF5-nitramide salts, M(SF5-
NNO2)x, that would offer (in comparison to the potassium salt
+
-
1
b) increased fluorine levels relative to the weight of metal.
The fluorine-to-metal ratios (atoms of F/g of M) in various M
SF5NNO2)x show the following order: Li (x ) 1), 5/7 ) 0.71;
Al (x ) 3), 15/27 ) 0.56; Mg (x ) 2), 10/42 ) 0.42; Na (x )
), 5/23 ) 0.22; K (x ) 1), 5/39 ) 0.13. From the standpoint
Description of the Crystal Structures of SF5-Nitramide
Salts: NH4(SF5NNO2) (1a), K(SF5NNO2) (1b), NH2C(d
NH2)NH2(SF5NNO2) (1d), and NH2C(dNH2)NHNH2(SF5-
NNO2) (1e). In recent times, there has been considerable interest
in the structural chemistry of the SF5 moiety, as evidenced by
its appearance in numerous reports containing X-ray crystal
(
1
of increased fluorine level, Li(SF5NNO2) appears particularly
attractive, followed by the Al and Mg salts.
8a
structures. In these articles, the SF5 group appears as an anion,
An initial attempt to prepare Li(SF5NNO2) by the treatment
of 2 with LiOCH3/MeOH (similar to the preparation of 1b; see
Experimental Section) appeared to give a high concentration
of the desired lithium salt in the reaction solution (by TLC
analysis; visualization with UV light). However, all attempts
to isolate the salt from the solution resulted in decomposition
to products that were no longer UV active, a strong indication
8
b
8c-f
as part of an oxyanion, and as part of larger anions.
It
(
7) The Merck Index, 10th ed.; Merck & Co., Inc.: Rahway, NJ, 1983.
The solubilities of the Li, Mg, and Al fluoride salts in water are 0.13
g/100 mL (25 °C), 87 mg/L (18 °C), and 0.559 g/100 mL (25 °C),
respectively. By contrast, the solubilities of the K, Na, and NH4 fluoride
salts are 96.4 g/100 mL (21 °C), 4.3 g/100 mL (25 °C), and 100 g/100
mL, respectively.
-
that the SF5NNO2 moiety was no longer present.
(
8) (a) Clark, M.; Kellen-Yuen, C. J.; Robinson, K. D.; Zhang, H.; Yang,
H.-Y.; Madappat, K. V.; Fuller, J. W.; Atwood, J. L.; Thrasher, J. S.
Eur. J. Solid State Inorg. Chem. 1992, 29, 809. (b) Heilemann, W.;
Mews, R.; Pohl, S.; Saak, W. Chem. Ber. 1989, 122, 427. (c) Winter,
R.; Gard, G. L.; Mews, R.; Noltemeyer, M. J. Fluorine Chem., 1993,
60, 109. (d) Klauck, A.; Seppelt, K. Angew. Chem., Int. Ed. Engl.
1994, 33, 93. (e) Geiser, U.; Schlueter, J. A.; Wang, H. H.; Kini, A.
M.; Williams, J. M.; Sche, P. P.; Zakowicz, H. I.; VanZile, M. L.;
Dudek, J. D.; Nixon, P. G.; Winter, R. W.; Gard, G. L.; Ren, J.;
Whangbo, M.-H. J. Am. Chem. Soc. 1996, 118, 9996. (f) Jacobs, J.;
Ulic, S. E.; Willner, H.; Schatte, G.; Passmore, J.; Sereda, S. V.;
Cameron, T. S. J. Chem. Soc., Dalton Trans. 1996, 383. (g) Bott, S.
G.; Clark, M.; Thrasher, J. S.; Atwood, J. L. J. Crystallogr. Spectrosc.
Res. 1987, 17, 187. (h) Gerhardt, R.; Grelbig, T.; Buschmann, J.; Luger,
P.; Seppelt, K. Angew. Chem., Int. Ed. Engl. 1988, 27, 1534. (i) Winter,
R.; Willett, R. D.; Gard, G. L. Inorg. Chem. 1989, 28, 2499. (j)
Damerius, R.; Leopold, D.; Schulze, W.; Seppelt, K. Z. Anorg. Allg.
Chem. 1989, 578, 110. (k) Pressprich, M. R.; Willett, R. D.; Terjeson,
R. J.; Winter, R.; Gard, G. L. Inorg. Chem. 1990, 29, 3058. (l) Keszler,
D. A.; Winter, R.; Gard, G. L. Eur. J. Solid State Inorg. Chem. 1992,
Another approach to the synthesis of Li(SF5NNO2) was from
1
a via ion exchange, using a method similar to that developed
+
-
for Z N(NO2)2 (a method based on the formation of
H N(NO2)2 , which is prepared in aqueous solution and shortly
+
-
+
- 2a
thereafter neutralized to give various Z N(NO2)2 ). In this
study, we determined that pentafluorosulfanylnitraminic acid,
H(SF5NNO2), can be prepared from 1a via ion exchange and
then neutralized with the appropriate bicarbonate or carbonate
to give the sodium, guanidinium, and aminoguanidinium SF5-
nitramide salts (1c,d,e) (eq 4).
2
9, 835. (m) Buschmann, J.; Damerius, R.; Gerhardt, R.; Lentz, D.;
However, when H(SF5NNO2) in H2O was similarly neutral-
ized with Li2CO3 to give the lithium salt in solution (analyzed
by TLC and F NMR), all attempts to isolate the salt resulted
Luger, P.; Marschall, R.; Preugschat, D.; Seppelt, K.; Simon, A. J.
Am. Chem. Soc. 1992, 114, 9465. (n) Wessolowski, H.; Roschenthaler,
G.-V.; Winter, R.; Gard, G. L.; Pon, G.; Willett, R. Eur. J. Solid State
Inorg. Chem. 1992, 29, 1173. (o) Wessel, J.; Hartl, H.; Seppelt, K.
Chem. Ber. 1986, 119, 453. (p) Kuschel, R.; Seppelt, K. J. Fluorine
Chem. 1993, 61, 23. (q) Henkel, T.; Klauck, A.; Seppelt, K. J.
Organomet. Chem. 1995, 501, 1. (r) Gilardi, R.; Flippen-Anderson, J.
L.; George, C. Acta Crystallogr., Sect. C: Cryst. Struct. Commun.
1991, 47, 442. (s) Preugschat, D.; Thrasher, J. S. Z. Anorg. Allg. Chem.
1996, 622, 1411.
1
9
(
5) Stern, A. G.; Koppes W. M.; Sitzmann M. E.; Nock, L. A.; Cason-
Smith, D. M. Process for Preparing Ammonium Dinitramide. U.S.
Patent 5,714,714, 1998.
(6) Koppes, W. M.; Sitzmann, M. E. Pentafluorosulfanylnitramide Salts.
U.S. Patent 5,441,720, 1995.

Pentafluorosulfanylnitramide Salts
Inorganic Chemistry, Vol. 39, No. 4, 2000 845
Table 1. Comparison of Physical Properties of Pentafluorosulfanylnitramide and Dinitramide Salts
mp (°C)a
density (g/cm3)
Z+SF
NNO
-
Z+N(NO
)
2 2
-
Z+SF
NNO
-
Z+N(NO
-
2
Z
5
2
5
2
2
)
NH
K
4
93
94
139
135
91
2.16
2.56
1.94
1.96
1.80
2.20
1.67
1.65
137
127
70
H
H
2
NC(dNH
NC(dNH
2
)NH
)NHNH
2
2
2
2
Na
78
107
a
+
-
+
-.
Decomposition point for Z SF
5
NNO ; slow decomposition for Z N(NO )
2
2
2
Figure 1. Formula unit and labeling scheme used for ammonium
pentafluorosulfanylnitramide (1a).
Figure 4. Formula unit and labeling scheme used for aminoguani-
dinium pentafluorosulfanylnitramide (1e).
Table 2. Metrical Parameters (Å, deg) for the Pentafluorosulfanyl
Moiety in Its Anions
nitramide ion
1
a
1b
1d
1e
S1-F1
S1-F2
S1-F3
S1-F4
S1-F5
1.573(3)
1.572(2)
1.567(2)
1.567(2)a
1.572(2)a
1.574(2)
1.574(2)
1.571(2)
1.566(2)
1.562(2)
1.559(2)
1.583(3)
1.575(3)
1.562(3)
1.574(3)
1.580(3)
1.5803(17)
1.5783(16)
1.5783(16)a
1.5803(17)a
Figure 2. Formula unit and labeling scheme used for potassium
pentafluorosulfanylnitramide (1b).
N1-S1-F1
N1-S1-F2
N1-S1-F3
N1-S1-F4
N1-S1-F5
F1-S1-F2
F1-S1-F3
F1-S1-F4
F1-S1-F5
F2-S1-F3
F2-S1-F4
F2-S1-F5
F3-S1-F4
F3-S1-F5
F4-S1-F5
174.7(2)
88.9(1)
95.8(1)
95.8(1)a
88.9(1)a
87.3(1)
87.8(1)
87.8(1)a
87.3(1)a
89.4(2) a
175.0(1)
89.2(2)a
91.5(2)a
174.61(13)
88.84(9)
174.6(1)
88.7(1)
95.5(1)
96.1(2)
88.9(1)
86.9(2)
87.5(1)
88.2(2)
87.9(1)
89.3(2)
175.0(1)
88.7(2)
91.4(2)
175.2(1)
90.3(1)
174.4(2)
88.8(2)
96.8(2)
96.1(2)
88.7(2)
87.5(2)
87.5(2)
87.4(2)
86.9(2)
90.2(2)
174.7(2)
88.6(2)
91.2(2)
174.3(2)
89.5(2)
96.33(9)
96.33(9)a
88.84(9)a
87.33(9)
87.43(9)
87.43(9)a
87.33(9)a
89.49(11)
174.67(9)a
89.31(16)
a
91.23(14)
Figure 3. Formula unit and labeling scheme used for guanidinium
pentafluorosulfanylnitramide (1d).
a
174.67(9)a
89.49(11)a
175.0(1)
89.4(2)a
8g-n
also appears attached to carbon in many neutral organic
and
a
In 1a,b, F2/F5 and F3/F4 are related by a crystallographically
8
d,j,o-q
organometallic
compounds.
imposed mirror symmetry.
In seven previously determined structures containing the
3e,8j,r,s
N-SF5 moiety,
the observed geometries are remarkably
moiety as well as those in this study. The N-S-F2 and N-S-
F5 angles are always less than 90°, and the N-S-F3 and
N-S-F4 angles are always greater than 90°. In 1a,b,d,e the
average of the former is 88.83(8)° while the average of the latter
is 96.10(38)°. This corresponds to a tipping of the SF5 group
away from the direction of greatest congestion, the substituent
on the central amine N atom (cf. Figure 4). Table 2 contains
comparative metric data for the four new SF5NNO2 salts
reported herein.
Dinitramides, and the four SF5-nitramide salts reported herein,
contain nitramine (N-NO2) groups, but the characteristics of
the N-NO2 moieties are quite different. The N-N bond lengths
most clearly illustrate this. In dinitramide salts, the two N-N
bonds in each anion are usually asymmetric, averaging 1.381
similar (see Table S30 in the Supporting Information). In the
absence of steric effects due to substituents on the central
nitrogen atoms, equivalent bond lengths and bond angles of the
N-SF5 moiety show remarkable agreement. In all of these
N-SF5 structures a similar numbering scheme has been chosen
to facilitate comparisons. If one looks down the F(1)-S-N axis
with the projection of the N-N vector in the vertical plane, the
equatorial F atoms are numbered from F(2) to F(5) in a
counterclockwise sense starting from the bottom left. Figures
1
-4 show the formula units for each structure and illustrate
the numbering scheme used.
Using this numbering scheme, some general trends can be
observed in the seven previous structures containing the N-SF5

846 Inorganic Chemistry, Vol. 39, No. 4, 2000
Sitzmann et al.
Figure 5. Packing diagram for ammonium pentafluorosulfanylnitra-
mide (1a).
Figure 6. Packing diagram for potassium pentafluorosulfanylnitramide
(1b) showing the trigonal prismatic coordination environment about
the potassium ion.
Å for the longer and 1.356 Å for the shorter.2b-2i In the N-SF5
salts, there is just one N-N bond length, which is considerably
shorter than either of these lengths at 1.297(6), 1.316(4),
1.301(4), and 1.317(5), for 1a,b,d,e, respectively. Thus, in these
latter salts, this bond has values which place it much closer to
NdN compared to N-N and this indicates that, in all N-SF5
2
structures, N(1) is sp hybridized. This is also borne out by the
S-N-N angle which is very close to 120° in all cases compared
to the N-N-N angles in the dinitramide structures which have
an average value of 114.9°.
Figure 7. Formula unit and labeling scheme used for the monoclinic
polymorph of aminoguanidinium dinitramide (3a).
A search of the Cambridge Structural Database for com-
pounds containing the N-NO2 moiety gave 408 hits. For the
N-N bond, a mean value of 1.374(38) Å was obtained with
minimum and maximum values of 1.266 and 1.494 Å. A survey
of all those examples where the N-N distance was less than
the bond angles subtended at K where the largest trans angle is
only 138.9(1)°.
The packing assemblies of both 1d and 1e are dominated by
multiple hydrogen-bonding interactions between the cation
protons and the oxygen and fluorine atoms of the anion. In 1d,
the hydrogen bonding is such that there are sheets primarily in
the bc plane made up of six pairs of anions and cations linked
in a circular fashion. These sheets are linked together by further
hydrogen bonds to make up a three-dimensional network.
1
.340 Å showed 27 examples, of which 5 were charged
compounds, 13 were neutral compounds, and 9 were compounds
in which the N-NO2 was a ligand in a metal complex. In these
three types of nitramine compounds containing short N-N
bonds, the average length of this bond was 1.310(18), 1.322(13),
and 1.294(17) Å, respectively, for those containing charged,
Description of Two Crystal Structures for Aminoguani-
dinium Dinitramide NH2C(dNH2)NHNH2[N(NO2)2] (3).
Monoclinic (3a) and triclinic (3b) crystal forms have been found
in samples of 3. The two forms have been analyzed by X-ray
diffraction and, though different, both are extensively linked
by hydrogen bonding. Figures 7 and 8 show the formula unit
and atom labeling for 3a,b, respectively. In structures containing
the dinitramide anion, there is often considerable asymmetry2
in the two halves of the anion, apart from those examples where
uncharged, and chelated nitramine moieties. For compounds
-
1
a-e which contain the (NO2)N(SF5) ion, the average N-N
bond length of 1.308(9) Å is similar to those of other structures
containing an anionic N-NO2 moiety.
The packing of 1a is dominated by the hydrogen-bonding
interactions of the ammonium protons with the anion. Two
protons link anions in the ac plane to form two antiparallel
chains in the a direction (see Figures S1-S3 in Supporting
Information). These two antiparallel chains are linked via
hydrogen bonds between the other two protons of the am-
monium ion and fluorine atoms of adjoining anions to form
zigzag chains in the bc plane in the c direction; the overall
packing scheme is illustrated in Figure 5.
b-i
2d,f
there is crystallographically imposed symmetry. To facilitate
comparisons between the structures of dinitramide salts, a
consistent labeling scheme has been used on the basis of this
asymmetry in which the N1-N2 bond is longer than the N1-
N3 bond and O2A and O3A are the exterior (anti) oxygen atoms
while O2B and O3B are the interior (syn) oxygen atoms.
In 1b, the potassium ion is in an eclipsed trigonal prismatic
environment, being surrounded by four fluorine and two oxygen
atoms, as is shown in Figure 6. This can also be clearly seen in
Ab initio and other theoretical calculations2c,9 on the di-
nitramide anion have concluded that the potential energy

Pentafluorosulfanylnitramide Salts
Inorganic Chemistry, Vol. 39, No. 4, 2000 847
fundamental difference; in 3a, the two hydrogen bonds are
accepted by a nitro group at one end of the anion, while in 3b
they are accepted by the central nitrogen atom and two nitro
oxygen atoms at the side of the anion. Other hydrogen bonds
link the ions into sheets; in 3b, there is also one out-of-plane
hydrogen bond linking these sheets.
Conclusions
+
-
Certain SF5-nitramide salts, Z SF5NNO2 , were successfully
prepared via nucleophilic displacements from carbamates and/
or ion exchange techniques. Although these same methods
appeared to give solutions containing high concentrations of
Li, Mg, and Al(SF5NNO2)x, these particular salts are apparently
unstable in the solid state and decomposed during isolation
procedures. The instabilities of these salts may be due to metal
complexation with oxygen which causes a loss of resonance
stabilization. Another possible driving force for these instabilities
is the formation of insoluble fluoride salts. Compared to the
corresponding dinitramide salts, the SF5-nitramide salts are less
thermally stable but are significantly more dense.
Figure 8. Formula unit and labeling scheme used for the triclinic
polymorph of aminoguanidinium dinitramide (3b).
surface for rotation of the nitro groups is very shallow. It was
2c
found that the important factors in producing molecular orbitals
similar to those found for experimental geometries were
inequivalent N-N bond lengths, some twisting of the nitro
groups, and a smaller NNN angle than that predicted from
optimized geometry. Of particular interest in dinitramide
structures is both the asymmetry in the N-N bond lengths and
the value of the NNN bond angle. In all dinitramide structures
The structures reported herein contain two related types of
-
-
anions, N(NO2)2 and SF5N(NO2) . From a structural point of
view, the major difference between them concerns the N-N
distances and the angles subtended at the central nitrogen atom.
In 3, there are two nonequivalent N-N (average lengths
2
3
2
this angle is intermediate between that expected for sp and sp
hybridization of the central N atom. If this atom was sp
hybridized, this would allow complete delocalization of the π
1
1
.372(2) and 1.354(2) Å) with an average N-N-N angle of
15.8(3)°. On the other hand, in 1a,b,d,e the average N-N
3
electrons while sp hybridization allows the two independent
conjugated halves of the molecule to twist while still remaining
conjugated to one of the lone pairs on the central N atom.
Calculations suggest that a 27° twist of the NO2 out of the NNN
distance is 1.308(9) Å and the average N-N-S angle is
20.0(5)°. For the former this clearly indicates a hybridization
1
3
2
of the central N which is neither sp nor sp while in the latter
the hybridization of the central N is clearly more closely related
to sp . The dinitramide anions are only slightly distorted from
3
plane as the best geometry for a conjugated system with a sp -
2
hybridized central N atom and a 0° twist for a sp -hybridized
2
1
0
central N atom. From these studies, it can be seen that the
metrical parameters of the dinitramide ion can be strongly
influenced by its environment.
planarity due to predominantly in-plane hydrogen-bonding
interactions.
The most striking feature of the pentafluorosulfanylnitramide
anion is its remarkable metrical similarity in all crystal structures.
The structure of this anion is apparently intrinsically rigid; this
is in marked contrast to the dinitramide salts where there is a
range in the conformations adopted by the anions in different
Previous structural determinations2 of salts containing the
dinitramide ion have shown that this entity actually does exhibit
considerable flexibility. Table 3 lists the metrical parameters,
while Table 4 lists conformational parameters relating to the
dinitramide ions in 3a,b. Since 3a,b are polymorphs, any
differences in the metrical parameters of the dinitramide ion in
these structures can be ascribed to the differences in their
packing and in their hydrogen-bonding scheme. As it turns out,
the hydrogen-bonding arrangements and the anionic conforma-
tions are similar in many respects, but there are qualitative
differences. For both 3a,b, all except one of the hydrogen bonds
are nearly parallel to the plane of the dinitramide ion. This has
the effect of constraining the conformations adopted by the
terminal NO2 groups to be very close to planar. The dinitramide
ions in 3a,b adopt conformations (see Table 4) in which the
terminal NO2 groups are rotated by only 2.9 and 3.3° (for 3a)
and 6.0 and 7.8° (for 3b) from the N1-N2-N3 plane. In
structures of other less constrained dinitramide ions, rotations
b-i
2b-i
environments.
Experimental Section
CAUTION! Compounds 1 are energetic oxidizers and can be
explosiVe under certain conditions. They should be handled with care
behind adequate shielding.
Reagents. The preparation and purification of SF
5
NdCdO,3a SF
(2) have been described
/MeOH was prepared by cautious addition of
potassium metal (washed with hexane to remove mineral oil) to MeOH,
which was under N and cooled in an ice bath. Other reagents used
5
Nd
11
3d
2
CCl ,
5 2 2 2 7 3
and SF N(NO )CO (CH ) CH
previously. KOCH
3
2
were commercially available.
Measurements. 19F NMR spectra for 1 were recorded from H
2
O
3
solutions using a Varian XL-200 spectrometer with CFCl as the
external reference at 0 ppm. Infrared spectra were from solids in pressed
2
e
of up to 30.3° have been observed. Figures 7 and 8 show, in
each case, the bidentate planar hydrogen bonding between the
cation and anion in the formula unit. However, there is a
-1
KBr pellets and were recorded in cm with a Perkin-Elmer model
1600 series FT-IR spectrometer. Melting points were obtained on a
Thomas-Hoover apparatus and are uncorrected. TLC was performed
using 250 µm Silica gel GF plates with CH
3
CN/CH
2 2
Cl (50/50) as the
(
9) (a) Politzer, P.; Seminario, J. M. Chem. Phys. Lett. 1993, 216, 348.
b) Michels, H. H.; Montgomery, J. A., Jr. J. Phys. Chem. 1993, 97,
602. (c) Mebel, A. M.; Lin, M. C.; Morokuma, K.; Melius, C. F. J.
developer (all 1 exhibit an R of approximately 0.3 under these
conditions).
Elemental analyses for 1 were performed by Galbraith Laboratories,
F
(
6
Phys. Chem. 1995, 99, 6842. (d) Leroy, G.; Sana, M.; Wilante, C.;
Peeters, D.; Dogimont, C. J. Mol. Struct. (THEOCHEM) 1987, 153,
2
Inc., Knoxville, TN. The salts with high oxidant balance (i.e., little or
+
no fuel in Z ; 1a-c) tended to give poor analyses, whereas the salts
49. (e) Leroy, G.; Sana, M.; Wilante, C.; Peeters, D.; Bourasseau, S.
J. Mol. Struct. (THEOCHEM) 1989, 187, 251.
10) (a) Brinck, T.; Murray, J. S.; Politzer, P. J. Org. Chem. 1991, 56,
012. (b) Politzer, P.; Seminario, J. M.; Concha, M. C.; Redfern, P.
C. J. Mol. Struct. THEOCHEM 1993, 287, 235.
+
containing appreciable fuel in Z (1d,e) gave acceptable results. Thus,
(
5
(11) Tullock, C. W.; Coffman, D. D.; Muetterties, E. L. J. Am. Chem. Soc.
1964, 86, 357.

848 Inorganic Chemistry, Vol. 39, No. 4, 2000
Sitzmann et al.
5 2
Table 3. Metrical Parameters (Å, deg) for Dinitramide Anions and Nitramide Fragments in SF NNO Anions
crystal
1a
1b
1d
1e
3a
3b
N1-N2
1.297(6)
1.709(4)
1.259(5)
1.258(5)
1.316(4)
1.693(3)
1.252(4)
1.251(3)
1.301(4)
1.692(3)
1.263(3)
1.231(3)
1.317(5)
1.681(4)
1.251(5)
1.252(4)
1.370(4)
1.352(4)
1.233(4)
1.209(4)
1.239(5)
1.219(4)
1.375(3)
1.355(3)
1.240(3)
1.195(3)
1.239(3)
1.208(3)
N1-N3/S1
N2-O2A
N2-O2B
N3-O3A
N3-O3B
N2-N1-N3/S1
N1-N2-O2A
N1-N2-O2B
O2A-N2-O2B
N1-N3-O3A
N1-N3-O3B
O3A-N3-O3B
119.5(3)
115.3(4)
126.1(4)
118.6(4)
119.4(2)
114.6(2)
125.8(3)
119.6(3)
120.6(2)
113.6(2)
126.8(3)
119.6(2)
120.4(3)
114.8(3)
125.0(4)
120.2(4)
116.1(3)
111.4(3)
126.6(3)
122.0(3)
111.7(3)
126.0(3)
122.3(3)
115.6(2)
110.6(3)
126.5(3)
122.8(3)
112.2(3)
125.9(3)
121.8(2)
Table 4. Selected Twist and Torsion Angles and Distances for the
Dinitramide Anions in 3a,b
were quickly determined by spotting the fraction onto a TLC plate and
visualizing with UV light. The combined fractions (total of 25 mL)
were quickly neutralized with sodium carbonate (0.06 g, 0.55 mmol)
param
3a
3b
2
before the H O was allowed to evaporate in a current of air in the
a
a
b
b
twist
twist
bend
bend
i
j
i
j
(deg)
(deg)
(deg)
(deg)
2.9
3.3
0.2
0.4
2.494
0.5
7.8
6.0
2.7
1.5
2.506
12.0
hood overnight. The crystalline residue was dried for several hours in
a vacuum desiccator (over Drierite) to yield 0.22 g (100%) of product,
mp 77-78 °C, dec. Dissolution in a very small amount of MeOH,
c
followed by the addition of CH
2
Cl
mp 78-79 C, dec. F NMR: δ 83.7 (quintet), 61.7 (d). IR: 1412,
1347 (NNO ), 867-788 (SF ). Anal. Calcd for F NaO S: F, 45.22;
N, 13.34; S, 15.26. Found: F, 35.97; N, 12.49; S, 14.08.
Preparation of 1d. A solution of H(SF NNO ) was prepared in the
same manner as for the synthesis of 1c described above. Neutralization
with guanidine carbonate, [NH C(dNH)NH ‚H CO , followed by
removal of water as above, gave 100% yield of crystals, mp 122-124
o
2
, gave 0.19 g (90%) of white crystals,
O‚‚‚O (Å)
tors (deg)
mean dev (Å)
dev O2B, O3B (Å)
o
19
d
e
N
2
0.016
0.02, 0.009
0.031
0.19, 0.18
2
5
5
2
f
a
5
2
A measure of the amount by which either nitro group (the ith or
the jth) has rotated out of the N2-N1-N3 plane, which is calculated
by averaging the two N-N-N-O torsion angles for a particular nitro
group (values are first brought below 90° by adding or subtracting 180°).
2
]
2 2
2
3
b
This represents the pyramidalization of the nitro N atoms with
C, dec. Dissolution in a small amount of CH
addition of CH Cl , gave a 79% yield of white crystals, mp 127-128
C, dec. F NMR: δ 83.7 (quintet), 61.7 (d). IR: 3445-3212 (NH),
1666 (CdN), 1384,1317 (NNO ), 884-771 (SF ). Anal. Calcd for
CH S: C, 4.86; H, 2.45; F, 38.44; N, 28.34; S, 12.96. Found:
3
CN, followed by the
2
3
expected values of 0° for ideal sp and 54.8° for ideal sp conformations.
2
2
c
d
o
19
The separation of the two closest nitro oxygen atoms. A pseudo-
torsion angle defined between the two closest N-O bonds in the
2
5
molecule belonging to different nitro groups, e.g., O2B-N2‚‚‚N3-
6 5 5 2
F N O
e
O3B. Mean deviation (Å) from the plane defined by O2A, N2, N1,
C, 5.10; H, 2.53; F, 37.82; N, 28.47; S, 12.72.
f
N3, and O3A. Deviation of O2B and O3B from plane defined above.
Preparation of 1e. Using the same procedure as described above
for 1d, but substituting aminoguanidine bicarbonate [NH
NHNH ‚H CO ] in the neutralization step, gave after crystallization
from CH CN/CH Cl a 70% yield of white crystals, mp 70-72 °C,
dec. 19F NMR: δ 83.7 (quintet), 61.7 (d). IR: 3488-3178 (NH), 1681,
666 (CdN), 1395, 1319 (NNO ), 892-773 (SF ). Anal. Calcd for
CH S: C, 4.58; H, 2.69; F, 36.23; N, 32.06; S, 12.23. Found:
C, 4.74; H, 2.79; F, 36.41; N, 32.40; S, 12.41.
Attempted Preparation of Li(SF NNO ). Treatment of 2 with
LiOCH /MeOH, similar to the preparation of 1b described above, gave
a methanol reaction solution that appeared by TLC analysis to contain
a high concentration of the desired Li(SF NNO ); i.e., there was a very
strong spot (visualized with UV light) at R ) 0.30 (same R as for all
2
C(dNH)-
our primary evidence of high purity for all 1 is based on their 19F NMR
2
2
3
spectra (only peaks present were a doublet and a quintet for the SF
5
3
2
2
group). Additional evidence for the purity of the salts includes their
constant melting points, consistent IR spectra, and TLC behavior
1
2
5
7 5 6 2
F N O
(exhibiting only one spot).
Preparation of 1a. Treating 2 with NH
with mp 89-92 °C, dec. In this study, additional purification
3
in CH
2
Cl
2
precipitates 1a
6
5
2
[
chromatography on Silica gel 60; CH
3
9
CN/CH
2
Cl
was used to give mp 93-94 °C, dec. F NMR: δ 83.7 (quintet), 61.7
d). IR: 3148 (NH), 1404, 1345 (NNO ), 867-789 (SF ). Anal. Calcd
for H S: H, 1.97; F, 46.31; N, 20.49; S, 15.63. Found: C, <0.5;
2
(50/50) as eluent],
3
1
(
2
5
5
2
F N O
4 5 3 2
F
F
H, 1.98; F, 45.88; N, 22.11; S, 16.32.
1). In all attempts to isolate the salt by removal of the solvent, it was
converted to materials that were not visible on a TLC plate with UV
Preparation of 1b. An improved method for 1b directly from 2
-
light. This loss of UV activity showed that the SF
no longer present.
5
NNO
2
group was
and KOCH
.09 mmol) in MeOH (5 mL) was stirred at -50 to -60 °C, while
adding dropwise a solution (3.7 mL) containing KOCH (0.16 g, 2.28
3
/MeOH is as follows: A solution containing 2 (0.72 g,
2
3
An attempt to prepare and isolate Li(SF
analogous to the preparation of 1c from H(SF NNO
(using Li CO for neutralization), also failed. Again, TLC analysis of
5 2
NNO ), by a method
mmol) in MeOH. The solution was allowed to warm and then was
held in a water bath at 25 °C while the volatiles were removed under
5
2
) as described above
2
3
reduced pressure. The residue was stirred with CH
87%) of white crystals, mp 130-133 °C, dec. Two recrystallizations,
by dissolving the product in a small amount of MeOH and adding CH
2
Cl
2
to give 0.41 g
the neutralized aqueous solution indicated a high concentration of the
desired Li(SF NNO ), but removal of the water from the aqueous
solution left a residue that showed no activity with UV light. An
(
5
2
2
-
1
9
Cl
3.7 (quintet), 61.7 (d). IR: 1413,1343 (NNO
Calcd for F KN S: F, 42.00; K, 17.29; N, 12.39; S, 14.18. Found:
2
, gave a 70% yield of crystals, mp 137-138 °C, dec. F NMR: δ
immediate workup of a small sample of the aqueous solution by rapid
8
2
), 874-788 (SF ). Anal.
5
removal of H O under vacuum in a desiccator over Drierite gave the
2
1
9
5
O
2 2
same result (the residue showed no UV activity). The F NMR
spectrum of the aqueous solution (shortly after its preparation) indicated
F, 36.86; K, 17.58; N, 11.89; S, 13.69.
19
Preparation of 1c. A solution of 1a (0.21 g, 1.02 mmol) in 2 mL
only the presence of Li(SF
(d). After standing overnight in the NMR tube, the aqueous solution
(by 19F NMR) still contained mainly Li(SF
NNO ), but small peaks at
δ 42.3, -7.3, and -128 were also present at that time.
5 2
NNO ). F NMR: δ 83.6 (quintet), 61.7
of distilled H
2-100 ion-exchange resin (prewashed with distilled H
O was used for elution, and the fractions containing H(SF
2
O was added onto a column containing 9 g of Dowex 50
O). Distilled
NNO
×
2
5
2
H
2
5
2
)

Pentafluorosulfanylnitramide Salts
Inorganic Chemistry, Vol. 39, No. 4, 2000 849
Table 5. Crystal Data and Summary of Intensity Data Collection and Structure Refinement
param
formula
1a
1b
1d
1e
3a
3b
H
4
F
5
N
3
O
2
S
F
5
N
2
O
2
SK
CH
247.17
monoclinic
P2 /n
6
F
5
N
O
5 2
S
CH
7
F
5
N
O
6 2
S
CH
181.14
7
N
7
O
4
7 7 4
CH N O
M
r
205.12
monoclinic
P2 /m
5.3534(4)
5.5989(4)
10.5851(9)
90
226.18
monoclinic
P2 /m
5.170(2)
5.4260(10)
10.577(4)
90
101.49(3)
90
290.76(17)
2
262.19
triclinic
P1h
181.14
triclinic
P1h
system
space group
a (Å)
b (Å)
c (Å)
monoclinic
Pc
3.599(1)
7.279(1)
13.938(2)
90
93.27(2)
90.0
364.5(1)
2
1
1
1
5.3674(3)
12.6148(9)
12.544(1)
90
93.926(9)
90.0
7.0662(8)
8.096(1)
8.3129(9)
92.190(9)
107.875(9)
99.145(7)
444.95(9)
2
7.097(3)
7.360(3)
8.251(3)
105.34(3)
94.59(4)
115.12(3)
367.1(3)
2
R (deg)
â (deg)
γ (deg)
101.055(9)
90
3
V (Å )
311.38
2
2.188
847.4(1)
4
Z
D
(mg/mm3)
2.583
1.937
1.957
1.650
1.639
c
cryst size (mm)
cryst color
temp (°C)
0.34 × 0.30 × 0.03 0.60 × 0.40 × 0.02 0.46 × 0.45 × 0.17 0.47 × 0.12 × 0.02 0.30 × 0.15 × 0.06 0.20 × 0.20 × 0.05
colorless
223(2)
colorless
293(2)
0.710 73
1.337
colorless
295(2)
1.541 78
4.261
colorless
294(2)
1.541 78
4.136
colorless
293(2)
1.541 78
1.383
colorless
294(2)
1.541 78
1.374
λ (wavelength) (Å)-
1.541 78
µ (abs coeff) (mm 1) 5.517
goodness of fit
1.104
0.0518
1.074
1.060
1.049
1.162
1.060
a
R-factors R(F)
0.0460
0.1128
0.0417
0.1051
0.0558
0.1593
0.0536
0.1502
0.0638
0.1187
0.0426
0.1021
0.0361
0.0764
0.0356
0.0859
0.1056
0.1292
0.0481
0.1113
2
(
all data) wR(F ) 0.1353
a
R-factors R(F)
0.0468
2
[I > 2σ(I)] wR(F ) 0.1303
a
2
2
)2]}1/2, wherein ∆ ) (F 2
- F 2). b Scattering factors: Atomic scattering factors
c
R-factors: R ) ∑|F
o
| - |F
c
||/∑|F
o
| and R
w
) {∑(w∆ )/∑[(F
o
o
from ref 13.
Attempted Preparations of Mg(SF
A column of ion-exchange resin, saturated with either Mg or Al ions,
was prepared by passing aqueous MgSO or Al(NO ‚9H O, respec-
tively, through Dowex 50 × 2-100 ion-exchange resin (prewashed with
distilled H O). Aqueous 1a was added onto the Mg and Al ion-exchange
columns which were then washed with water to give solutions appearing
to contain the Mg or Al SF NNO salt (by TLC analysis with UV light).
5
NNO
2
)
2
and Al(SF
5
NNO
2
)
3
.
(OCH
4.91; N, 4.87; S, 11.16. Found: C, 25.11; H, 4.87; N, 4.45; S, 11.29.
c) SF NdC(NHCMe . Anhydrous ether (80 mL), Me CNH (3.5
g, 48 mmol), and SF NdCCl (6.6 g, 30 mmol) were combined at -196
C, after which the mixture was slowly warmed and then stirred at 25
C for 24 h. The precipitate (Me CNH ‚HCl) was removed (vacuum
CNH (3.5 g, 48 mmol) was added, and after
4 h, precipitate was again removed. Adding more Me CNH (3.5 g,
8 mmol) and stirring for 14 d gave a final amount of precipitate which
2 6 14 5 2
), 149 (NHCO). Anal. Calcd for C H F NO SSi: C, 25.08; H,
4
3
)
3
2
(
)
3 2
5
3
2
5
2
2
°
°
3
2
5
2
filtration), additional Me
3
2
However, removal of the water from the solutions gave residues that
exhibited no UV activity, indicating both salts decomposed under these
2
4
3
2
conditions.
Preparation of Z N(NO
was also removed. The solvent was removed to give a crystalline residue
(6 g) from which fractional vacuum sublimation at 35 °C (stopped after
ca. 90% was sublimed) produced 5.17 g (59%) of pure product, mp
+
-. NH
)
2 2
2 2 2 2 2
C(dNH )NHNH [N(NO ) ] (3).
The aminoguanidinium dinitramide salt was prepared as follows: A
mixture of Ba(OH) ‚8H O (1.05 g, 3.33 mmol, purity ) 83% based
on H O solubility) in distilled water (25 g) was stirred for 15 min before
it was filtered to remove insoluble BaCO . The filtrate was stirred under
while aminoguanidinium sulfate (0.88 g, 3.33 mmol) was added,
after which the mixture was filtered to remove the precipitate of BaSO
The filtrate was stirred under N , and ammonium dinitramide (0.96 g,
.7 mmol) was added in one portion. Removal of the H O under reduced
pressure and drying the residue gave white crystals (1.20 g, 99%, mp
0-79 °C). Several recrystallizations from ethyl acetate raised the mp
to 91-94 °C. Anal. Calcd for CH : C, 6.63; H, 3.90; N, 54.14.
Found: C, 6.79; H, 3.69; N, 53.79.
Preparation of Precursors to SF
COOCMe . Freshly distilled Me COH (3 mL, 32 mmol) was frozen
at -196 °C and degassed by several freeze-thaw cycles before SF Nd
CdO (1.35 g, 8 mmol) was condensed onto the frozen alcohol. After
h at 25 °C, the excess alcohol was evaporated and the residue was
vacuum sublimed at 35 °C to give 0.94 g (48%) of white crystals, mp
1
9
2
2
62-63 °C. F NMR (CDCl + 1% TMS): δ 79.7, δ 104.0, J
3
A
B
AB
)
1
2
155 Hz; H NMR (CDCl + 1% TMS): δ 1.41 (CH ), 4.20 (NH),
3
3
5.20 (NH); 13C NMR (CDCl + 1% TMS): δ 30 (CH ), 52 (NHC).
3
3
3
N
2
9 20 5 3
Anal. Calcd for C H F N S: C, 36.35; H, 6.78; N, 14.14; S, 10.76.
4
.
Found: C, 36.99; H, 6.96; N, 14.32; S, 11.09.
2
X-Ray Experimental Details. Data Collection. Clear, colorless
crystals of 1a,b,d,e, and 3a,b, synthesized as described above, were
glued to the ends of thin glass fibers and transferred to a Siemens R3/V
7
2
7
(for 1e) or a Siemens P4/S diffractometer using Mo KR (1e) or Cu KR
7 7 4
N O
radiation and a graphite monochromator. Cell dimensions and an
orientation matrix for data collection were obtained from a least-squares
refinement of the setting angles of at least 25 accurately centered
reflections. These are listed with other relevant crystal data in Table 5.
5 5
-Nitramide Salts. (a) SF NH-
3
3
5
Structure Solution and Refinement. The structures were solved
by direct methods using the SHELXTL package of computer pro-
2
12
13a
grams. Neutral atom scattering factors were used with corrections
13b
for real and imaginary anomalous dispersion. All structures were
refined by full-matrix least-squares methods based on F using
SHELXL-96 and used all unique data. Non-hydrogen atoms were
1
9
1
1
10-111 °C. F NMR (CDCl
3
+ 1% TMS): δ
+ 1% TMS): δ 1.50 (CH
+ 1% TMS): δ 28 [(CH ], 84 (CMe
Anal. Calcd for C NO S: C, 24.69; H, 4.14; N, 5.76; S, 13.18.
Found: C, 24.61; H, 4.17; N, 5.74; S, 13.50.
b) SF NHCOOCH CH SiMe . Anhydrous ether (2 mL) and freshly
distilled Me SiCH CH OH (1.5 mL, 10.5 mmol) were frozen at -196
C and degassed by several freeze-thaw cycles before SF NdCdO
0.85 g, 5 mmol) was condensed onto the frozen mixture. After 12 h
at 25 °C, removal of the solvent and vacuum sublimation of the residue
A
75.6, δ
), 7.26 (NH).
), 148 (NHCO).
B
70.9, JAB
)
2
1
13
55 Hz. H NMR (CDCl
3
3
C
14
NMR (CDCl
3
3
)
3
3
refined anisotropically while hydrogen atoms were located in difference
Fourier syntheses and refined isotropically. A summary of the refine-
ment details and the resultant refinement agreement factors is contained
in Table 5. Fractional coordinates, bond distances and angles, and
anisotropic displacement parameters are provided in the Supporting
Information.
H
3 10
F
5
2
(
5
2
2
3
3
2
2
°
(
5
19
(12) Sheldrick, G. M. SHELXTL, Crystallographic System; Siemens
at 35 °C gave 0.73 g (52%) of white crystals, mp 63-64 °C. F NMR
+ 1% TMS): δ
1% TMS): δ 0.03 (SiMe
Analytical Instrument Division, Madison, WI, 1986.
1
(CDCl
3
A
71.9, δ
), 0.93 (CH
+ 1% TMS): δ 1.6 [Si(CH
B
68.8, JAB ) 149 Hz. H NMR (CDCl
), 4.19 (OCH ), 7.32 (NH).
], 18 (CH Si), 66
3
(
13) (a) Cromer, D. T.; Waber J. T. International Tables for X-ray
Crystallography; The Kynoch Press: Birmingham, England, 1974;
Vol. IV, Table 2.2. (b) Cromer, D. T. Ibid., Table 2.3.1.
+
3
2
2
13
C NMR (CDCl
3
)
3 3
2

850 Inorganic Chemistry, Vol. 39, No. 4, 2000
Sitzmann et al.
Acknowledgment. This work was supported by the NSWC
wishes to acknowledge the financial support from the Office
of Naval Research, Mechanics Division.
Independent Research Program and the ONR 6.2 Program.
R.J.B. wishes to acknowledge the ASEE-Navy Summer Faculty
Research Program for the award of Summer Faculty Fellowships
to the Naval Research Laboratory for the summer of 1998. R.G.
Supporting Information Available: Tables S1-S31, listing crystal
data, atomic coordinates, bond lengths and angles, and anisotropic
displacement parameters for 1a,b,d,e, and 3a,b, geometric data for all
5
SF NX structures, and hydrogen bond parameters for 1a,d,e and 3a,b,
(14) Sheldrick, G. SHELXTL96 Acta Crystallogr. A 1990, 46, 467. This
is a full-matrix least-squares refinement package that uses all data
and refines on F rather than the traditional F. The various parameters
Figures S1-S3, showing packing diagrams for 1a, and an X-ray
crystallographic CIF file. This material is available free of charge via
the Internet at http://pubs.acs.org. Crystallographic data for the six
structures have also been deposited with the Cambridge Crystallographic
Data Centre (CCDC, 12 Union Road, Cambridge CB2 1EZ, U.K.
E-mail: deposit@ccdc.cam.ac.uk).
2
used in this refinement process are defined as follows: R(F) ) ∑|Fo
2
2
2 2
2 2 1/2
-
1
Fc|/∑Fo; R(F ) ) {∑[w(Fo - Fc ) ]/∑[w(Fo ) ]} , where w )
2 2
/[σ (Fo) + (aP) + bP] and a and b are variable parameters whose
optimal values are usually suggested by the program during the
refinement process. The goodness-of-fit parameter (s) is based on F
and defined as s ) {∑[w(Fo - Fc ) ]/[n - p]} , where n is the
number of reflections and p is the total number of parameters refined.
2
2
2 2
1/2
IC991281I