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New Compounds with Apatite or Garnet Structure.

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heated in the absence of a solvent at ca. 200 " C , CI migrates
from B to the N, atom of the N3 group, NZ is split off, and
hexachloroborazole is formed.
pounds of apatite structure that have defects in the cation
part of the lattice. Similar compounds ( I ) and (2) exist in
the binary system La203/SiO~,but here there are long series
of mixed crystals of type ( l a ) and (2a) that extend up to the
ternary silicate apatites ( I b ) and ( 2 b ) having filled cationic
I
"2
If diphenylboron azide is heated with benzonitrile phenylimide as 1,3-dipolar agent, the phenylboron phenylimide,
C6Hs-B -N-C6H5, that is formed as intermediate, acts as a
dipolarophile and undergoes a 1,3-dipolar cyclization to
yield a B-containing five-membered ring compound (1,2,4,Striazaboroline); this reaction provides the first evidence for
occurrence of a boron imide.
Boron imides stable at room temperature are obtained when
aromatic amines such as p-anisidine, p-thioanisidine, or
2,4,6-trimethylaniline are treated with pentafluorophenylboron dichloride in boiling toluene [reaction (c)]. These
compounds undergo a 1,3-dipolar reaction with benzonitrile
N-oxide or phenyl azide, even at room temperature, which
leads to heterocyclic five-membered ring compounds (1,2,4,Soxadiazaborolines; tetrazaborolines) in almost quantitative
yield. The BN stretching vibrations are IR-inactive but
appear as intense bands in the Raman spectrum just above
1700 cm-1. Unexpectedly, C6HsBC12 and C6HsNH2 yield a
monomeric boron imide with anIR-inactive but Raman-active
BN stretching vibration at 1658 cm-1.
parts of the lattice. In sum the ternary system SrO/La203/Si02
contains a n extensive region of mixed crystals with the
apatite structure.
Except for the natural berzeliites [21, the garnets ( 3 ) have
hitherto presented no example with a quinquevalent element
in the tetrahedral sites, which is surprising since in other
respects there are many relationships between silicates and
phosphates, arsenates, and vanadates. After unsuccessful
experiments with various phosphate systems, we were able to
prepare a series of arsenate (3a) and vanadate (3b) garnets,
and our first attempts with fluoride systems led to synthesis
of the cryolithionite (3c). At higher temperatures the products
decompose in various ways; for instance, after formation of
a tetragonal phase a t 850 " C , Na3Fe2As3012 decomposes at
900 "C with loss of As203 and 0 2 and formation of cc-Fe2O3
and Na3As04.
Lecture at Marburg on December 9th, 1966
[VB 52 IE]
German version: Angew. Chem. 79, 583 (1967)
[ * ] Priv.-Doz. Dr. P. Paetzold
Institut fur Anorganische Chemie der Universitat
Meiserstrasse 1
8 Munchen 2 (Germany)
[l] W. H . Sounders and J. C . Ware, J. Amer. chem. SOC.80,
3328 (1958).
New Compounds with Apatite or Garnet Structure
By H. Schwarz[*j
Ternary compounds Mf1(XV04)2 have the same structure
when MI1 = Sr or Ba and X v = P, As, V, or Cr. Isomorphous
replacement of the cations, in accordance with a general
leads, when x = 2,
formula Mf!,Mfy(XV04)2-,(Xv10~)x,
to double compounds of the type M11Mi(XV104)2 which,
without exception, 'have the structure of the parent when
XVI = Cr, Se, or S, MI = K, NH4, Rb, or TI, and MI1 = Sr,
Pb, or Ba (Ba only when XvI = Cr) [I]. The compounds can
generally be obtained by a thermal route or by precipitation
from very concentrated M?XVI04 solutions. In agreement
with this it was found for some more extensively studied
M f X V ~ 0 4 / M ~ ~ X systems
v ~ 0 4 that only the 1:1 double salts
exist and that there are n o regions of solid solution.
A second type of coupled replacement leads, from Sr3(P04)z1
to a series of unusual apatites. If the P5+ in the parent
Sr3(PO4)2 is replaced by Si4+ and at the same time Sr2+ is
a
partially replaced by La3+ [Sr9-,La,(P04)6-,(Si04),1,
surprising change in structure occurs. From x = 4.5
[Sr4.~La4.~(P04)1.~(Si04)4.~1
to x = 6 [SnLa6(Si04)61 only a
single phase, which has the apatite structure, occurs; when
x = < 4.5 the products are a mixture of Sr3(PO4)2 and the
apatite phase for x = 4.5. Sr3La6(SiO& itself is the y = 0
member of a mixed-crystal series Sr3-,,La6+2,,/3(Si04)6 that
exists from y = 1 to y = -1. Here are for the first time comAngew. Chem. internat. Edit. 1 Vof. 6 (1967)
I No. 6
To set alongside calcium hydroxoaluminate Ca3[A!(OH)&
which was earlier recognized as a defect garnet structure
(4) [31, we have obtained a series of further "hydrogarnets"
(4a) and (46) by two methods; precipitation from solution
can generally be used; but the second method, in which anhydrous oxometalates 3M110.MzIIO~are treated with steam
under pressure gives purer products. As a n example of the
often complex process of thermal decomposition of such
"hydrogarnets" we may mention the decomposition of
Ca3A12(0H)12 which affords 3CaO.AI203 only above 900 "C
and by way of two intermediate stages.
Inorganic Colloquia at Gottingen on January 23rd, 1967, and at Giessen
[VB 60 IE]
on February loth, 1967
German version: Angew. Chem. 79. 584 (1967)
[*I Priv.-Doz. Dr. H. Schwarz
Institut fur Anorganische Chemie
der Technischen Hochschule
Englerstr. 11
75 Karlsruhe (Germany)
[l] H . Sclzwurz, Z . anorg. allg. Chem. 344, 41, 214 (1966); 345,
230 (1966).
[2] Z.B. W. Bubek and F. Muchatschki, Z . Kristallogr., Mineralog. Petrogr., Abt A 90, 44 (1935).
[3] E. Brundenberger, Schweiz. rnineralog. petrogr. Mitt. 13, 569
(19 3 3).
573
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