On the reaction of hexachlorocyclotriphosphazene with heptamethyldisilazane. Crystal structure of P3N3Cl 5{N(CH3)[Si(CH3)3]}

Article abstract of DOI:10.1135/cccc20071407

The reaction of P₃N₃Cl₆ (1) with heptamethyldisilazane in the molar ratio 1:1 leads to the formation of 2,4,4,6,6-pentachloro-N-methyl-N-(trimethylsilyl)cyclotriphosphazen-2-amine, P₃N₃Cl₅{N(CH₃)[Si(CH ₃)₃]} (2). Compound 2 was characterized by elemental analysis and spectroscopically. Molecular and crystal structures of 2 were determined by X-ray diffraction. 2 is monoclinic, space group P2₁/n. Experimental data were compared with results of DFT calculations.

Full text of DOI:10.1135/cccc20071407

Crystal structure of P3N3Cl5{N(CH3)[Si(CH3)3]}
1407
ON THE REACTION OF HEXACHLOROCYCLOTRIPHOSPHAZENE
WITH HEPTAMETHYLDISILAZANE. CRYSTAL STRUCTURE OF
P3N3Cl5{N(CH3)[Si(CH3)3]}
b
a3
Radka VOZNICOVÁa1, Milan ALBERTI , Jan TARABAa2, Dalibor DASTYCH
,
a4
a5,
Pavel KUBÁČEK and Jiří PŘÍHODA
*
a
Department of Chemistry, Faculty of Science, Masaryk University,
Kotlářská 2, 611 37 Brno, Czech Republic; e-mail: voznic@post.cz, taraba@chemi.muni.cz,
dastych@chemi.muni.cz, kubacek@chemi.muni.cz, prihoda@chemi.muni.cz
Department of Physical Electronics, Masaryk University,
1
2
3
4
5
b
Kotlářská 2, 611 37 Brno, Czech Republic; e-mail: alberti@chemi.muni.cz
Received February 27, 2007
Accepted August 15, 2007
Th e reaction of P3N3Cl6 (1) with h eptam eth yldisilazan e in th e m olar ratio 1:1 leads to th e for-
m ation of 2,4,4,6,6-pen tach loro-N-m eth yl-N-(trim eth ylsilyl)cyclotriph osph azen -2-am in e,
P3N3Cl5{N(CH3)[Si(CH3)3]} (2). Com poun d 2 was ch aracterized by elem en tal an alysis an d
spectroscopically. Molecular an d crystal structures of 2 were determ in ed by X-ray diffraction .
2 is m on oclin ic, space group P21/n. Experim en tal data were com pared with results of DFT
calculation s.
Keyw ord s: Ph osph azen es; Cyclotriph osph azen e; X-ray diffraction ; IR spectroscopy; Ram an
spectroscopy.
Th e ch em istry of ph osph azen es was exten sively studied in th e last 40 years.
Th e research was carried out in th e field of preparation an d reactivity of lin -
ear as well as cyclic ph osph azen es with th e aim to prepare suitable precur-
sors for syn th eses of ph osph azen e polym ers. Detailed in form ation on th e
presen t state of art in th is field can be foun d in m on ograph s1,2
.
A com m on reaction of ph osph azen es is th e n ucleoph ilic substitution of
h alogen atom s. Th ese reaction s were m ostly studied with h exah alogen o-
cyclotriph osph azen e P3N3X6 (X = F, Cl, Br)1, th eir am m on olysis an d
am in olysis bein g th e m ost sign ifican t reaction types. Th e exten t of th e sub-
stitution depen ds on th e am in e, type of solven t, etc. Th e results of th ese
studies were sum m arized in refs1,3,4
.
So far, relatively little atten tion h as been paid to reaction s of cyclic
ph osph azen es with silylated am in es. Th e reaction s of P3N3Cl6 (1) an d som e
am idoph osph azen es with h exam eth yldisilazan e (HMDSN) were studied by
Collect. Czech. Chem. Commun. 2007, Vol. 72, No. 10, pp. 1407–1419
© 2007 Institute of Organic Chemistry and Biochemistry
doi:10.1135/cccc20071407

1408
Voznicová, Alberti, Taraba, Dastych, Kubáček, Příhoda:
som e auth ors5–7. However, on ly th e results of Fields an d Allen 7 can be con -
sidered as correct. Th ey isolated an d ch aracterized a gem in al derivative
P3N3Cl4[NHSi(CH3)3]2 th at was form ed in th e reaction of P3N3Cl4(NH2)2
with HMDSN in th e absen ce of solven t. Latter Allen an d Brown com pleted
th is work by publish in g spectroscopic data for th is com poun d an d deter-
m in in g its crystal an d m olecular structures8. Niecke et al.9 syn th esized
partly silylated fluorocyclotriph osph azen es, P3N3F5[NHSi(CH3)3], P3N3F5-
{N(CH3)[Si(CH3)3]}, P3N3F5{N[Si(CH3)3]2} an d P3N3F5{N(C2H5)[Si(CH3)3]},
by th e reaction of am in open tafluorocyclotriph osph azen e or th e corre-
spon din g N-alkylated derivatives with (C2H5)2NSi(CH3)3. All th ese products
were fully ch aracterized by IR an d NMR spectroscopies, m ass spectrom etry,
an d elem en tal an alysis. Recen tly, th ree n ovel silylam in o derivatives, i.e.
P3N3Cl5[NHSi(CH3)3], P3N3Cl2[NHSi(CH3)3]4 and P3N3Cl2(NH2)2[NHSi(CH3)3]2,
were prepared an d ch aracterized10
.
Th is paper deals with th e reaction of P3N3Cl6 with h eptam eth yldisilazan e
(HPMDSN). Th is reaction h as n ot been studied till n ow an d its proposed
course is sh own in Sch em e 1.
SCHEME 1
EXPERIMENTAL
All procedures, syn th eses an d sam ple preparation s were perform ed usin g Sch len k tech n ique
un der dry n itrogen atm osph ere. Aceton itrile, dich lorom eth an e, dieth yl eth er an d n-h exan e
(Aldrich , p.a.) were purified an d dried accordin g to procedures described by Perrin an d
Arm arego11
.
Th e pure h exach lorocyclotriph osph azen e (1) was obtain ed from its m ixture with octa-
ch lorocyclotetraph osph azen e (BASF) by crystallization from n-h exan e an d subsequen t subli-
m ation in vacuum at 60 °C. Th e purity of 1 was determ in ed by m ass spectrom etry an d
31P NMR spectroscopy. HPMDSN (Aldrich , p.a.) was dried by storin g over m olecular sieve
(3 Å) for on e week, an d th en distillin g on a Vigreux colum n . Th e fraction boilin g at 144.0–
145.5 °C was collected an d th e purity of th e product was proved by Ram an spectroscopy.
1H, 13C an d 31P NMR spectra (δ, ppm ; J, Hz) were recorded usin g a Bruker Avan ce DRX
500 in strum en t at frequen cies 1H: 500.13 MHz, 13C: 125.77 MHz, 31P: 202.46 MHz, an d were
referen ced to tetram eth ylsilan e an d 85% solution of H3PO4 (extern al stan dard). Th e sam ples
were sealed in Sim ax tubes (diam eter 4 m m ), in serted in origin al Wilm ad NMR cuvettes
Collect. Czech. Chem. Commun. 2007, Vol. 72, No. 10, pp. 1407–1419

Crystal structure of P3N3Cl5{N(CH3)[Si(CH3)3]}
1409
(diam eter 5 m m ) an d th e space between th e cuvettes was filled with D2O (extern al lock).
Th e spectra were m easured in th e coaxial NMR cuvette system .
IR spectra (wavelen gth s in cm –1) were m easured with a Bruker IFS 28 spectrom eter in KBr
disks con tain in g 1.0–1.7 m g of th e sam ple an d 100 m g KBr. Ram an spectra (in cm –1) of solid
sam ples were m easured in Ram an capillaries usin g a Bruker IFS 55 Equin ox apparatus,
equipped with a FRA 106/S adapter (Nd:YAG laser, λ = 1064 n m , output 150–400 m W).
Diffraction data were collected usin g th e KUMA KM-4 κ-axis diffractom eter with graph ite-
m on och rom atized MoKα radiation (λ = 0.71073 Å) equipped with a CCD detector. All struc-
tures were solved by direct m eth ods, an d refin ed by full-m atrix least-squares m eth ods usin g
an isotropic th erm al param eters for th e n on -h ydrogen atom s. Th e software Xcalibur CCD
system 12 was used for data collection /reduction , an d th e SHELXTL software13 was used for
th e structure solution , refin em en t, an d drawin g preparation (th erm al ellipsoids are drawn at
th e 50 probability level).
Mass spectra were m easured usin g th e MAT Trio 1000, Series II, Fin n igan , excitation
en ergy 70 eV, con n ected to a gas ch rom atograph GC 8000 with DB-5 colum n . Th e sam ple
(1–2 µl) in a suitable solven t was in jected on to th e colum n , th e tem perature of th e h eated
zon e was 50–280 °C, an d th e h eatin g rate 10 °C/m in . Nitrogen was used as a carrier gas.
Th erm al beh avior was in vestigated with a Derivatograph (MOM, Budapest). Th e TG, DTG,
an d DTA curves were determ in ed in air up to 900 °C with a h eatin g rate of 2 or 10 °C/m in .
Th e quan tum ch em ical calculation s were carried out with th e m olecular ADF code, ver-
sion 2005.01 (refs14–16), usin g XC fun ction al LDA in cludin g VWN correlation fun ction al,
TZ2P basis set an d n o frozen core.
Syn th esis of 2,4,4,6,6-Pen tach loro-N-m eth yl-N-(trim eth ylsilyl)-
cyclotriph osph azen -2-am in e (2)
Hexach lorocyclotriph osph azen e (1; 2.548 g, 7.3 m m ol), aceton itrile (13 cm 3) an d HPMDSN
(1.350 g, 7.7 m m ol, 1.7 cm 3, 5% excess) were placed in to a Sch len k tube equipped with a
screw cap. Th e reaction m ixture was h eated on an oil bath at 126–132 °C for 16 h . After
coolin g, th e solven t was partly evaporated an d crystals were filtered off with a Sch len k frit
S4. Th e last residue of aceton itrile was rem oved in vacuum an d th e product was purified by
vacuum sublim ation at 70 °C. Yield 1.792 g, 60%. M.p. 92–93 °C. For P3N3Cl5{N(CH3)-
[Si(CH3)3]} (386.4) calculated: 11.59% C, 2.92% H, 42.77% Cl, 13.52% N, 22.42% P,
6.78% Si; foun d: 11.78% C, 2.92% H, 42.63% Cl, 13.40% N, 22.29% P, 6.37% Si. IR (KBr):
410 sh , 417 w, 500 sh , 514 st, 523 m , 533 sh , 552 w, 565 w, 582 vst, 647 w, 669 w, 693 vw,
764 sh , 769 m , 848 st, 862 sh , 868 sh , 882 w, 953 st, 1069 m , 1191 vst, 1199 sh , 1231 st,
1242 sh , 1257 m , 1264 sh , 1417 vw, 1436 vw, 1458 vw, 1464 vw, 2832 vw, 2900 vw,
2942 sh , 2962 vw, 2972 sh , 2981 sh , 2992 sh . Ram an (capillary): 130 vw, 163 m , 177 s,
186 w, 204 m , 214 w, 235 vw, 246 vw, 279 vw, 333 w, 343 m , 356 s, 366 m , 408 s, 518 vw,
532 vw, 556 bvw, 579 vw, 647 vs, 669 w, 693 vw, 769 m , 847 vw, 956 vw, 1067 vw,
1210 vw, 1126 vw, 1265 vw, 1415 vw, 1435 vw, 2832 vw, 2902 s, 2960 m , 2971 sh , 2983 w.
MS (EI), m/z (rel.%): M(th eor.) = 414.437 or 411.849 with respect to isotopic com position ;
412 (17) [M+], 397 (100) [M+ – CH3], 377 (15) [M+ – Cl], 339 (7) [M+ – Si(CH3)3], 325 (9)
[M+ – Si(CH3)4], 311 (28), 305 (25) [M+ – ClSi(CH3)3], 276 (73) [M+ – ClNSi(CH3)4], 269 (7)
[M+ – Cl2Si(CH3)3], 254 (40) [M+ – Cl2Si(CH3)4], 240 (40) [M+ – Cl2NSi(CH3)4], 219 (8)
[M+ – Cl3Si(CH3)4], 206 (9) [M+ – Cl3NSi(CH3)4], 161 (12) [M+ – Cl5NSi(CH3)4], 146 (22), 112
(20), 102 (77) [NSi(CH3)4+], 73 (75) [Si(CH3)3+], 59 (69). 1H NMR (CH2Cl2): 2.8 d (NCH3);
Collect. Czech. Chem. Commun. 2007, Vol. 72, No. 10, pp. 1407–1419

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Voznicová, Alberti, Taraba, Dastych, Kubáček, Příhoda:
1
0.37 s (SiCH3), JPH = 15. 13C NMR (CH2Cl2): 30.22 s (NCH3); 0.29 s (SiCH3). 31P{ H} NMR
2
2
(CH2Cl2): 22.3 dd (ClP{N(CH3)[Si(CH3)3]}); 21.4 d (PCl2), JPP = 50; 21.4 d (PCl2), JPP = 41.
RESULTS AND DISCUSSION
Com poun d 2 is poorly soluble in aceton itrile (2.3 g/100 cm 3) an d th erefore
th is solven t can be used for recrystallization . Th e solubilities of 2 in dieth yl
eth er an d dich lorom eth an e are h igh er (10 g/100 cm 3). Com poun d 2 is rela-
tively stable in air, wh ich was proved by IR an d Ram an spectra. Th e IR an d
Ram an spectra of 2, exposed to air m oisture for on e week, rem ain ed un -
ch an ged, as con firm ed by com parison with IR an d Ram an spectra of th e
sam ple th at was kept dry in a Sch len k vessel.
1
Th e H, 13C an d 31P NMR spectra of 2 were recorded in dich lorom eth an e.
1
Th e ch aracter of th e 31P an d 31P{ H} NMR spectra (Fig. 1a, 1b) at 303 K cor-
respon ds to th e substitution of on e ch lorin e atom in 1 (refs10,17).
1
It follows from th e structure of 2 th at 31P{ H} NMR spectrum (Fig. 1a)
sh ould be of ABC spin system . Doublet of doublets at 22.3 ppm (2JPP values
foun d in spectrum are 41 an d 50 Hz) belon gs to th e ph osph orus atom in
P(Cl)[N(CH3)3Si(CH3)3] group. Two oth er doublets at 21.4 ppm are observed
in th e rem ain in g part of th e spectrum . Accordin g to th e th eory, th ese sig-
n als sh ould be doublet of doublets but ch em ical sh ifts of both PCl2 groups
are so n ear (th e differen ce is on ly h un dredth s of ppm ) th at on ly doublets
are registered.
FIG. 1
1
31P NMR spectra of com poun d 2: { H} decoupled (a), coupled (b)
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Crystal structure of P3N3Cl5{N(CH3)[Si(CH3)3]}
1411
Th e coupled 31P NMR spectrum of 2 (Fig. 1b) can be con sidered as ABCX3
spin system due to th e in fluen ce of th e CH3 group bon ded to exocyclic
N-atom (3JPH = 18 Hz). Th e sh ape of th e m ultiplets in th e spectra is stron gly
in fluen ced by a sm all differen ce of th e ch em ical sh ifts of both groups. Th e
in teraction of CH3 proton s leads to splittin g of each lin e of th e sign al at
22.3 ppm , yieldin g th eoretically a quartet. Sin ce th ese m ultiplet lin es over-
lap, a broad sign al is observed.
The two resonance signals in the 13C NMR spectrum at 30.22 and 0.29 ppm ,
in tegral in ten sity 1:3, prove th e presen ce of two ch em ically n on equivalen t
1
CH3 groups in 2, N(CH3) an d Si(CH3)3. Th e H NMR spectrum also con firm s
th e proposed structure of 2.
Figure 2 sh ows th erm al beh avior of 2. It follows from th e DTA curve th at
2 m elts at 92–93 °C. Furth er h eatin g led to sublim ation of th e product. Th e
ability of 2 to sublim e was also con firm ed in a direct experim en t wh ere th e
total weigh t loss of th e sam ple was observed above 120 °C.
FIG. 2
Th erm al beh avior of com poun d 2
Vibrational Spectra
Th e m easured an d calculated IR an d Ram an spectra are sh own in Fig. 3.
The presence of the CH3NSi(CH3)3 group in P3N3Cl5{N(CH3)[Si(CH3)3]} (2)
affects th e ban ds in th ree region s:
a) An tisym m etrical (υas) an d sym m etrical vibration s (υs) valen ce ban ds of
CH3 groups (in trim eth ylsilyl an d m eth ylam in o groups) can com m on ly be
foun d in th e region 2800–3000 cm –1 (refs18,19). Th ese ban ds are broader an d
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1412
Voznicová, Alberti, Taraba, Dastych, Kubáček, Příhoda:
h ave weak in ten sity in th e IR spectrum (agreem en t with N(4)–CH3 vibra-
tion at 2946 cm –1 in th e sim ulated spectrum ), wh ile in Ram an spectrum
sh arp in ten sive lin es at 2960 (m ) an d 2902 (s–vs) cm –1 togeth er with oth er
less in ten sive ban ds are observed19. Th e substitution of Cl atom in P3N3Cl6
by CH3NSi(CH3)3 group leads to lower sym m etry (D3h → Cs). Th is ch an ge is
docum en ted by th e presen ce of m ore lin es in vibration spectrum of 2 com -
plem en ted with com bin ation lin es of weaker in ten sities an d h igh er h ar-
m on ic ban ds (overton es), e.g. 2 × δasCH3 (ref.18).
b) Ban ds in th e 1200–1500 cm –1 region arise by deform ation vibration s
δas an d δs of CH3 groups of th e above m en tion ed substituen t. δasSi–CH3 an d
δasN(4)–CH3 ban ds in th e 1464–1368 cm –1 region in IR spectrum , an d in th e
1468–1375 cm –1 region in Ram an spectrum (Fig. 3) are un resolved, with n u-
m erous overlaps. Th e in ten sive ban d at 1231 cm –1 togeth er with a sh oulder
FIG. 3
Measured an d calculated IR an d Ram an spectra of com poun d 2
Collect. Czech. Chem. Commun. 2007, Vol. 72, No. 10, pp. 1407–1419

Crystal structure of P3N3Cl5{N(CH3)[Si(CH3)3]}
1413
at 1242 cm –1 in th e IR experim en tal spectrum can be assign ed to δs vibra-
tion s of both types of CH3 groups, wh ile th e sam e ban ds are less in ten sive
in Ram an spectrum (Fig. 3). Th e correspon din g ban d at 1206 cm –1 for CH3
from th e Si–CH3 group was foun d in sim ulated IR spectrum . Th ese observa-
tion s are also in agreem en t with publish ed data19,20
.
It is worth wh ile to m en tion th e ban ds of sym m etrical valen ce vibration s
υ of endocyclic P and N atom s of com pound 2. These bands, at 1257 (st) cm –1
an d th e sh oulder 1264 (m ) cm –1, are of n egligible in ten sity in Ram an spec-
trum , but very in ten sive in IR spectrum . Th ese can be com pared with two
in ten sive ban ds at 1234 an d 1257 cm –1 in sim ulated IR spectrum an d litera-
ture data as well7,19,21–23
.
Th e m ost in ten sive ban d in IR spectrum is at 1191 cm –1, with a sh oul-
der at 1199 cm –1. Accordin g to th e ADF program , th is ban d arises by th e
com bin ation of valen ce vibration υas of exocyclic P(1)–N(4) bon d or
υasP(1)–N(4)–C(4) (th eoretically 1186 cm –1), an d υSi–N(4)–C(4). Sh ih ada24
assign ed th e ban d at 1115 cm –1 in IR spectrum , an d th e correspon din g
ban d at 1124 cm –1 in Ram an spectrum of th e com poun d Cl2PONHCH3 just
to th e υasP–N–C vibration . Sim ilarly, th e ban d of m edium in ten sity at
1069 cm –1 (1080 cm –1 in sim ulated ADF spectrum ) can be assign ed to
υN(4)–C(4) or υSi–N(4)–C(4) valen ce vibration s. Th e correspon din g values
were foun d in CH3N[Si(CH3)3]2 (ref.20). An oth er proof of substitution com es
from th e ban d at 953 cm –1 (954 cm –1 in sim ulated spectrum ) correspon din g
to th e vibration of exocyclic P(1)–N(4) bon d.
c) Furth er ban ds, providin g in form ation about substitution in 2, can
be foun d in th e 600–900 cm –1 region . Th ey can be assign ed eith er to
ρas(CH3) an d ρs(CH3) deform ation vibration s, or υasSiC3, υsSiC3, an d
υSi–N–C3 valen ce vibration s. Th e ban d observed at 848 cm –1 in IR spect-
rum (847 (vw) cm –1 in Ram an spectrum ; 835 cm –1 in ADF spectrum ) can be
un am biguously assign ed to ρas(CH3) deform ation vibration 18–20. Ban ds at
882 (w), 868 (sh ), 862 (sh ), 831, 823, an d 821 cm –1 in ADF spectrum ) corre-
spon d to υSiC3 valen ce vibration s.
Accordin g to literature data18, it is possible to assign th e 769 cm –1 ban d of
low or m edium in ten sity in IR spectrum (also 769 cm –1 in Ram an spectrum )
to ρs(CH3) deform ation vibration . Th e very in ten sive ban d at 647 cm –1 in
Ram an spectrum is due to υsSiC3 valen ce vibration , wh ile th e low in ten sity
ban ds at 669 cm –1 (Ram an ) an d 669, 647 cm –1 (IR) can be assign ed to
υasSiC3 valen ce vibration 18,20
.
Th e spectra calculated on th e used level of DF th eory h ave been useful in
th e assign in g experim en tal ban ds to a m ode of vibratory m otion , h owever
n ot in every case. Th e m olecule h as n o sym m etry an d is too big for h igh er
Collect. Czech. Chem. Commun. 2007, Vol. 72, No. 10, pp. 1407–1419

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Voznicová, Alberti, Taraba, Dastych, Kubáček, Příhoda:
level of precise calculation . Moreover, its stereoch em ical n on rigidity is
likely to worsen th e agreem en t between th eory an d experim en t.
The Crystal Structure of 2,4,4,6,6-Pentachloro-N-methyl-
N-(trimethylsilyl)cyclotriphosphazen-2-amine (2)
Sin gle crystals of 2 were grown from its con cen trated aceton itrile solution
at room tem perature over a period of few days.
Th e m olecular an d crystal structures of 2 were determ in ed by X-ray struc-
ture an alysis. Com poun d 2 is m on oclin ic, space group P21/n, Z = 4 (Fig. 4).
Th e basic crystallograph ic data are given in Table I an d selected bon d
len gth s an d an gles in Table II. Th e P3N3 rin g is sligh tly deform ed, wh ereas
th e P(1) atom bearin g th e CH3NSi(CH3)3 group is position ed off th e rin g
plan e. Th e m ean deviation of P(1) from th e rin g plan e is 0.2442 Å.
It follows from a com parison of th e m olecular structure of 2, P3N3Cl6
(ref.25) an d oth er m on osubstituted cycloph osph azen es th at th e P(1)–Cl(1)
bon d in 2 (2.0284 Å) is lon ger th an , e.g., in 1 (1.985 Å), but com parable to
oth er m on osubstituted derivatives (2.010–2.046 Å)26–28. Oth er P–Cl bon ds
in PCl2 groups of th e rin g rem ain ed un ch an ged. Th e N(4)–P(1)–Cl(1) an gle
is 106.25(7)°.
FIG. 4
Th e m olecular structure of com poun d 2. Th e th erm al ellipsoids of n on -h ydrogen atom s are
drawn at th e 50% probability level
Collect. Czech. Chem. Commun. 2007, Vol. 72, No. 10, pp. 1407–1419

Crystal structure of P3N3Cl5{N(CH3)[Si(CH3)3]}
1415
Th e space crystal structure arran gem en t (Fig. 5) con sists of ch ain s [010] in
wh ich th e m olecules of 2 form th e plan e (101). Th e ch ain s with th e
[ABAB]∞ m otive altern ate regularly. No m ore sign ifican t weak in teraction s
were observed.
TABLE I
Crystal data an d refin em en t param eters for com poun d 2
Em pirical form ula
M, g m ol–1
C4H12Cl5N4P3Si
414.43
T, K
120
Wavelen gth , Å
0.71069
Crystal system , space group
a, Å
m on oclin ic, P2(1)/n
15.496(3)
b, Å
6.1260(10)
c, Å
17.734(4)
β, °
109.51(3)
V, Å3
1586.8(5)
Z
4
Calculated den sity, Mg m –3
Absorption coefficien t, m m –1
F(000)
1.735
1.276
832
Crystal size, m m
θ ran ge for data collection , °
In dex ran ges
0.25 × 0.25 × 0.1
3.54–25.00
–20 ≤ h ≤ 17, –8 ≤ k ≤ 7, –22 ≤ l ≤ 23
10940/3645 [R(in t) = 0.0843]
98.4
Reflection s collected/un ique
Com pleten ess to 2θ = 25.00, %
Refin em en t m eth od
Data/restrain ts/param eters
Goodn ess-of-fit on F2
Fin al R in dices [I > 2σ(I)]
R in dices (all data)
Largest diff. peak an d h ole, e Å–3
Full-m atrix least-squares on F2
3645/0/158
1.085
R1 = 0.0359, wR2 = 0.1001
R1 = 0.0381, wR2 = 0.1025
0.843 an d –0.562
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1416
Voznicová, Alberti, Taraba, Dastych, Kubáček, Příhoda:
Th e agreem en t between th e data obtain ed from X-ray diffraction an d
from ADF calculation (Table II) can be observed from th e average of th eir
differen ce expressed in per cen t, wh ich is 0.7 for in tern uclear distan ces
(12 values) an d 0.8 for an gles (25 values). Th e deform ation of th e rin g in to
an approxim ate en velope con form ation can be ch aracterized by th e an gle
between two plan es: N(1)–P(1)–N(3) an d N(1)–N(2)–N(3) (see Fig. 4). Th is
an gle am oun ts to 16° (X-ray data) an d 17° (ADF calculation ). Th e m olecule
2 could well be stereoch em ically n on rigid because of th e low barrier to
rotation aroun d th e P(1)–N(4) bon d. With all oth er coordin ates optim ized
TABLE II
Selected experim en tal an d calculated bon d len gth s (in Å) an d an gles (in °) for com poun d 2
X-ray
ADFa
X-ray
ADFa
Bon d, Å
1.585(2)
1.589(2)
1.603(2)
2.028(1)
1.562(2)
1.480(2)
1.781(2)
1.847(2)
1.575(2)
1.991(1)
1.571(2)
1.568(2)
An gles, °
119.48(9)
109.21(7)
108.39(8)
110.08(7)
107.57(8)
100.68(3)
An gles, °
P(1)–N(3)
P(1)–N(1)
P(1)–N(4)
P(1)–Cl(1)
N(1)–P(2)
N(4)–C(4)
N(4)–Si(1)
Si–Cb
1.594
1.596
1.618
2.045
1.571
1.456
1.786
1.853
1.585
2.002
1.580
1.576
P(3)–N(2)–P(2)
N(3)–P(1)–N(1)
N(3)–P(1)–N(4)
N(1)–P(1)–N(4)
N(3)–P(1)–Cl(1)
N(1)–P(1)–Cl(1)
N(4)–P(1)–Cl(1)
P(2)–N(1)–P(1)
C(4)–N(4)–P(1)
C(4)–N(4)–Si(1)
P(1)–N(4)–Si(1)
C–Si–Cc
119.93(11) 122.2
116.30(9)
109.80(9)
111.51(9)
107.30(7)
105.00(7)
106.25(7)
116.7
108.6
111.5
108.0
105.9
105.5
121.20(10) 120.3
114.40(14) 115.0
119.59(14) 120.8
P(2)–N(2)
P–Clb
N(2)–P(3)
P(3)–N(3)
125.65(9)
110.33(9)
108.55(9)
119.40(9)
110.12(7)
108.13(8)
108.27(7)
108.39(8)
121.6
111.0
107.7
118.5
110.0
108.2
107.8
109.6
N–Si–Cc
N(1)–P(2)–N(2)
N(1)–P(2)–Cl(3)
N(2)–P(2)–Cl(3)
N(1)–P(2)–Cl(2)
N(2)–P(2)–Cl(2)
Cl–P–Clc
118.3
107.7
109.2
110.9
108.0
101.3
N(3)–P(3)–N(2)
N(3)–P(3)–Cl(5)
N(2)–P(3)–Cl(5)
N(3)–P(3)–Cl(4)
N(2)–P(3)–Cl(4)
P(3)–N(3)–P(1)
120.61(10) 120.8
a
b
c
All coordin ates optim ized with TZ2P basis an d n o frozen core. Average len gth . Average
an gle.
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Crystal structure of P3N3Cl5{N(CH3)[Si(CH3)3]}
1417
except for th e ch an gin g dih edral an gle ξ Cl(1)–P(1)–N(4)–Si, th e ADF calcu-
lation sh ows on e barrier for ξ = 0° an d an oth er for ξ = 180°. Th e barriers lie
at 0.51 an d 0.14 eV, respectively, above th e m in im a th at occur sym m etri-
cally for ξ = 100 an d 260°. Th e wh ole calculated en ergy profile is sh own in
Fig. 6.
FIG. 5
Th e crystal structure – perspective view th rough m olecular com position of com poun d 2
FIG. 6
Calculated en ergy profile for in tern al rotation of th e CH3NSi(CH3)3 group
Collect. Czech. Chem. Commun. 2007, Vol. 72, No. 10, pp. 1407–1419

1418
Voznicová, Alberti, Taraba, Dastych, Kubáček, Příhoda:
CCDC 294469 con tain s th e supplem en tary crystallograph ic data for th is
paper. Th ese data can be obtain ed free of ch arge via www.ccdc.cam .ac.uk/
con ts/retrievin g.h tm l (or from th e Cam bridge Crystallograph ic Data Cen -
tre, 12, Un ion Road, Cam bridge, CB2 1EZ, UK; fax: +44 1223 336033; or
deposit@ccdc.cam .ac.uk).
This work was supported by the Ministry of Education, Youth and Sports of the Czech Republic
(project MSM0021622411). The authors express their gratitude to the Grant Agency of the Czech
Republic (grant No. 203/02/0436).
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