Horstmann, Stefan

Schmidpeter, Alfred

Schnick, Wolfgang

English

Open Access LMU

Overview P-N Compounds: From the Single Tetrahedral Cation to Framework Structures Alfred Schmidpeter Institut fur Anorganische Oiemie, UniversitätMünchen, D-80333München, Germany Stefan Horstmann and Wolfgang Schnick Laboratorium fur Anorganische Chemie, Universität Bayreuth, 0-95440Bayreuth, Germany T he element combination PN is isoelec~ tronic to SiO (f ig. I ) . How much practical impact is connected to this statement? L i t e the hydrolysis of S1C14, the ammonolysis of PCI5 is accompanied by a condensa-tion. The complexity of this reaction already was realized when it was first investigated: *Thatscche ist, wenn Chlorophosphor mit Ammoniak zusammeruojmmt, so entsteht positiv Salmiak m grosser Menge. Seme BiÜimg setzt nothwendigdie Bildung von Amiden voraus; allem die Zusammensetzung der Chhrphosphore ist so, dass sich kern einfaches Amid bilden kann" Μ Justin Liebig wrote this in a letter [2] dated November 12> 1832 to Friedrich Wohler. The condensation (Fig. 2) [3] leads to cyclic oligomers and linear polymers (phosphazenes) and ends with a product of the empirical composition HPN 2 . I t was described [4J and named phospham as early as 1846. It is isoelectronic with silicon dioxide and in fact resembles the latter in its high chemical stability, but only now the structural analogy of the two has been proven [5]. By using excess liquid ammonia for the ammonolysis, the condensation can be suppressed and only the product of substitution, the tetraaminophosphoniumchloride, is obtained (Equation 1) [6, 7]. PCI5 + 8NH3 • N H 3 [Ρ(ΝΗ 2) 4ΐα + 4ΝΗ 4 α (1) The pure product is obtained by reacting the byprod­uct, ammonium chloride, wi th diethylamine and removing the formed diethylamine hydrochloride. N H 4 C l + ( C 2 H 5 ) 2 N H N H 3 + ( C 2 H 5 ) 2 N H 2 C l (2) A n alternative preparation starts from phosphoro/ of condensation. A two step sequence leads to thionic triamide SP(NH?)$ and thus avoids any risk tetraaminophosphonium iodide (Equation 3) [8» 9], SP(NH 2 ) 3 CH3I +3ΝΗ» CH>SPKNH2),1I -CH 3 SH [P(NH 2 )JI (3) 8 Volume 2. Number ·/. Main Group Chemistry Kens O v e r v i e w FIGURE 1 IsoeledronicSiOaridPNspedes SK>V ο ο 0 \ ,Ο" ΝΗ2 H2N NH2 V " 2 u NH2 HgPN*+ HtzP^N» Justin Uebig Friedrich WöHer (S1O2)» Ο l I HN I (HPN2>x FIGURE 2 The product pattern of the ammonolysis or PCI5 substitution c ο η d e η s a t i ο η PC! 5 - PCI3NH2ICI - [PCt2(NH2)2lCI - IPC!(NH2)3]CI- [P(NH2)41CI ι ι I [NPCyn lNP(NH2)da cydophosphazenes [KPNHJx phospham Main Group Chemistry News. Volume Ζ Number 4 O v e r v i e w tion number of 7 is realized, resembling a TH-analo-gous structure (Fig. 4). A n essential feature for the arrangement of the cations in both structures is the formation of N-H.. . .X hydrogen bonds. The reaction of the tetraaminophosphoni-urn ion with phosphorus pentachloride gives access to doubly branched phosphazenes (Equation 4) [6]. [P(NH 2 ) 4 ]* + 4PC15- » [P(NPC13)4]* + 8HC1 (4) By the influence of bases, the tetraaminophosphoni-urn salts condense to triaminophosphazo-tri-aminophosphonium salts (Equation 5) [6J. base 2[P(NH 2) 4]+ » [ ( N H 2 ) 3 P N P ( N H 2 ) 3 ] ^ N H 4 * (5) According to the X-ray structure determination, both salts contain the tetraaminophospnonium ion. In the cation, phosphorus and nitrogen form a markedly dis-torted tetrahedron, with a P-N distance of 160.7(2) pm being the shortest P - N H 2 bond ever reported. In the iodide, a CsCl analogous coordina-tion of cations and anions is found (Fig. 3) [10]. Contrary to this, in IP(NH 2) 4]C1, a mutual coordina-Thermal condensation of [P(PNH2)4JX-salts leads to These compounds are also obtained by het-phosphorus-nitride-imides with different hydrogen erogenous ammonolysis reactions (Equations 6 and 7) content, such as H P N 2 or H P 4 N 7 [10]. of pure and crystalline P3N5 [11]. 58Q°C;14d P3N5 + N H 3 > 3HPN 2 (6) 820°C;14d 4P 3 N 5 + NH 4 C1 » 3 H P 4 N 7 + H C 1 (7) Both compounds are built up by three-dimensional framework structures of corner sharing PN4-tetrahe-d i a [ l l J. The structure of H P N 2 [5], which is isoelec-tronic to S i0 2 , corresponds to the ß-cristobalite type (Fig. 5), the high temperature modification of S i0 2 . The structure of H P 4 N 7 can be regarded as a shear variant of the H P N 2 structure, which results by eliminating one N H 3 from four formula units of HPN 2 . The valences of the P-N framework are satu-rated by nitrogen which are bonded to three phos-phorus atoms according to the formula £[P 4WN 5p 2lN 2Wi The hydrogen-free phosphorus(V) nitride P3N5 is obtained in a pure and microcrystalline form by reacting (PNC1 2 ) 3 w i t h ammonium chloride, according to Equation 8 [11]. (PNC1 2) 3 + 2NH 4C1 760° C; 2d P 3 N 5 + 8HC1 (8) The reaction is carried out in sealed glass ampules and the size of the batch is limited by the pressure caused by formation of hydrogen chloride. The decomposition of tetraaminophosphoniumchloride (Equation 9) [7] is without these limits. L300°C;10- 3 bar 3[P(NH 2) 4]Ct » P 3 N 5 + 3NH 4C1 + 4 N H 3 (9) 2.750°C;lbar 10 Volume 2. Number 4, Main Group Chemistry News O v e r v i e w FIGURE 3 The coordination of the tetraaminophosphonium ion in [P(NH2)4]I FIGURE 4 The coordination of the tefraaminophosphonium ion by chloride in [P{NH2)4]CI. According to the formula i i^W^PJN^ 3 ! ] , c o n t a i n s two types of nitrogen atoms, with 3/5 bonded to two phos-phorus atoms and 2/5 bonded to three atoms. The structure is dominated by a stacking disorder, as demonstrated by HRTEM investigations [11], By reaction of P3N5 with L i 3 N ternary phosphorus, nitrides with P-N anions are accessible. In the quasi-binary system Ü3N/P3N5, LiPN 2 is the compound with the highest Ρ content. It has a three-dimen­sional framework structure ^[ΡΝ^Ί which is isotypic to HPN 2 or ß-cristobalite [12], In L i 1 2 P 3 N 9 , the anion [P 3 N 9 ]U-(Fig. 6) corresponds to the cyclotrisilicate anion [S13O9]6' [13]. In L17PN4, isolated [PN4]7*tetrahedra isoelectronic to ortho-silicate anions are found (Fig. 7) [14]. A compound containing the anion [H4PN4] 3 ' isoelectronic to H4SLO4 is obtained from the reaction of P3N5 and CsNH 2 [15]. Li5P2N5 contains no ÜP2N5 5*] layers, but isolated [P4N10]10" anions have been found (Fig. 8) [16]. A compound containing the anion [ H ^ N J Q ] * ' has been obtained from the reaction of P3N5 and N a N H 2 [17]. These anions are isosteric to molecular phosphorus pentoxide P4O1Q or to silicic esters S14O5 (OR) 4 with bulky substituents R. A n analogue to layer-silicates has not been found yet. A n arrangement analogous to chain-silicates is real-ized in the calcium phosphorus nitride Ca2PN3 (Fig. 9) [18]. The synthesis is analogous to that of the Li-salts by reacting the basic metal nitride C a 3 N 2 with the acidic non-metal nitride P3N5 (Equation 10). FIGURE 5 The structure of HPN 2 FIGURE 6 The structure of the anion PaNy 1 2 - in L1J2P3N9 Alain Group Chemistry News, Volume 2, Number 4 ii O v e r v i e w 2Ca 3 N 2 + P3N5 800°C;14d »1 3Ca 2PRj (10) Because most of the ternary phosphorus nitrides con-tain structural analogues to the silicates, i t seemed to be a promising task to search for P -N frameworks with zeolite-like structures. The synthesis of a P-N zeolite succeeded by treating P3N5 and volatile metal halide with ammo-nia at 640° C (Equation 11) |19]. 4P 3 N 5 + 4 N H 3 + 5ZnCl 2 640° C Z n 5 H 4 I P 1 2 N 2 4 ] C l 2 + 8HC1 (11) In a subsequent reaction with additional zinc chlo-ride, a complete exchange of the hydrogen is possible (Equation 12). Z n 5 H 4 [ P 1 2 N 2 4 l C l 2 + 2 Z n C 1 2 700° C; 3d Z n 7 l P 1 2 N 2 4 ] C l 2 + 4HCI (12) The cubic compound is isostructural to sodalite, Nag[Al6Si$0 2 4]Cl 2 . The alumosilicate framework is replaced by a nitrido phosphate framework (Fig. 10). I n the center of the ß-cage, a Cl~ ion is found which is tetrahedrally surrounded by metal cations Z n 2 + . A more elegant method for preparation of P-N sodalites is the direct reaction of metal dihalides with phosphorus nitride iminde (Equation 13) [11]. 5MX 2 + 12HPN 2 700°C; 2d Ρ M 5 H 4 [ P 1 2 N 2 4 ] X 2 + 8HX (13) A large number of compounds has been realized in this manner containing, for example, M g 2 + , Z n 2 + , Co 2 * , Ni 2 +, C u 2 + or Pb 2* as cations and F~, C I ' , Br" or Γ as anions. A striking feature of several P-N sodalites is their intense color. The cobalt and nickel containing compounds are blue, the iron containing brown and Cr and T i containing materials are green. A P-N sodalite without a central halide ion is accessible by reaction of zinc nitride with phospho­rus nitride (Equation 14) [20]. 2 Z n 3 N 2 + 4 P 3 N 5 750°C; 7d Zn6[P 1 2 N 2 4 ] (14) The P-N framework in this compound is the same as i n Ζ η 7 [ Ρ ι 2 Ν 2 4 ] 0 2 , but the zinc atoms are disordered. Indications have been found that Znä[P 1 2N 2 4] might be useful as a hydrogen storage material. As shown in this overview, several examples for the structural analogy between SMD and P - N compounds do exist. Typical silicate building blocks and the corresponding P-N isosteres show different formal charges, as Si04 4 '/PN 4 7 ' , SijO^I?^11' or Si0 2/PN 2- > but in ternary and higher compounds, the P-N substructures correspond to the respective sili-cate structures. 12 Volume 2, Number 4P Main Group Chemistry News O v e r v i e w FIGURE 7 The structure of the anion PN47* in U7PN4 FIGURE 8 The structure of the anion P4N10 1 0" in lijofyNlO Using this structural analogy, i t should also be possible to obtain phosphorus nitrides analogous to nanoporous zeolites or layered silicates which might be materials with promising technical rele-FIGURE 9 The structure of the anion i i P N 3 4 " j in Ca2PN3 vance. References and notes 1. From W, Uwicki, "Wähler and Liebig—Briefe von 1829-1873 " J. Cromm Vertag, Göttingen, p. 63 (1982). 2. "When chlorophosphorus and ammonia are brought together, much ammonium chloride is formed. This necessitates the formation of amides; the composition of chlorophosphorus is such however, that no simple amide can form.'' 3. A. Schrnidpeter et al., Z. Natwforxh., B24,799 (1969) and literature cited there. 4. M.C Gerhardt, Aim. Chm. Fhys., 18,188 (1846); C.R. Acad. Sci.t 22,858(1846). 5. W. Schnick and J. Lücke, Ζ. Anorg. Aifc. Chem., 610,21 (1992). 6. A. Schrnidpeter and C Weingand, Angew. Chem., 81,573 (1969); Angew. Chem. Int. Ed. End., 8,615 (1969). 7* S. Korstmann and W. Schnick, unpublished results. 8. A. Schrnidpeter and C Weingand, Angew. Chem., 80,234 (1968); Angew. Chem. Int. Ed. EngL, 7,210 (1968). 9. W. Schnick et aL, Angew. Chem., 106,818 (1994); Angew. Chem. Int. Ed. Engl, 33,785 (1994). tO. S. Horstmann and W. Schnick, Z. Natwi/orscft., (in press). 11. W. Schnick, Angew. Chem., 105,846 (1993); Angew. Chem. Int. Ed. Engl., 32,806 (1993). 12. W. Schnick and J. Lücke, Z. Anorg. Alfe. Chem., 588,19 (1990). 13. U . Berger and W. Schnick, unpublished results. 14. W.Schnickar-lJ.UfckeJ.SoWSt^ 15. H. Jacobs and F. Gotinski, Z. Anorg. ABg. Chem., 620,531 (1994). 16. W. Schnick and U . Berger, Angew. Chem., 103,857 (1991); Angew. Chem. Int. Ed. EngL, 30,830 (1991). 17. H. Jacobs et al., Z. Anorg. A%. Cherry 620,1213 (1994). 18. W. Schnick and V. Schultz-Cotilon, Angew. Chem., 105,308 (1993); Angew. Chem. Int. Ed. EngL, 32,280 (1993). 19. W. Schnick and J. Lücke, Angew. Chem., 104,208 (1992); Angew. Chem. Int. Ed. Engl, 31,213 (1992). 20. F. Wester and W. Schnick, unpublished results. FIGURE 10 The ß-cage of Ζ ^ Ρ ^ Ν ^ Κ ^ Main Group Chemistry News, Volume 2, Number 4 13 

P-N-Compounds. From the Single Tetrahedral Cation to Framework Structures

Universität München: Elektronischen Publikationen

Overview 
P-N Compounds: From the Single 
Tetrahedral Cation to Framework Structures 
Alfred Schmidpeter 
Institut fur Anorganische Oiemie, UniversitätMünchen, D-80333München, Germany 
Stefan Horstmann and Wolfgang Schnick 
Laboratorium fur Anorganische Chemie, Universität Bayreuth, 0-95440Bayreuth, Germany 
T he element combination PN is isoelec~ tronic to SiO (f ig. I ) . How much practical impact is connected to this statement? L i t e the hydrolysis of S1C14, the 
ammonolysis of PCI5 is accompanied by a condensa-
tion. The complexity of this reaction already was 
realized when it was first investigated: 
*Thatscche ist, wenn Chlorophosphor mit 
Ammoniak zusammeruojmmt, so entsteht positiv 
Salmiak m grosser Menge. Seme BiÜimg setzt 
nothwendigdie Bildung von Amiden voraus; 
allem die Zusammensetzung der Chhrphosphore 
ist so, dass sich kern einfaches Amid bilden 
kann" Μ 
Justin Liebig wrote this in a letter [2] dated 
November 12> 1832 to Friedrich Wohler. 
The condensation (Fig. 2) [3] leads to cyclic 
oligomers and linear polymers (phosphazenes) and 
ends with a product of the empirical composition 
HPN 2 . I t was described [4J and named phospham as 
early as 1846. It is isoelectronic with silicon dioxide 
and in fact resembles the latter in its high chemical 
stability, but only now the structural analogy of the 
two has been proven [5]. 
By using excess liquid ammonia for the 
ammonolysis, the condensation can be suppressed 
and only the product of substitution, the 
tetraaminophosphoniumchloride, is obtained 
(Equation 1) [6, 7]. 
PCI5 + 8NH3 • 
N H 3 
[Ρ(ΝΗ 2) 4ΐα + 4ΝΗ 4 α (1) 
The pure product is obtained by reacting the byprod­
uct, ammonium chloride, wi th diethylamine and 
removing the formed diethylamine hydrochloride. 
N H 4 C l + ( C 2 H 5 ) 2 N H N H 3 + ( C 2 H 5 ) 2 N H 2 C l (2) 
A n alternative preparation starts from phosphoro/ of condensation. A two step sequence leads to 
thionic triamide SP(NH?)$ and thus avoids any risk tetraaminophosphonium iodide (Equation 3) [8» 9], 
SP(NH 2 ) 3 
CH3I +3ΝΗ» 
CH>SPKNH2),1I 
-CH 3 SH 
[P(NH 2 )JI (3) 
8 Volume 2. Number ·/. Main Group Chemistry Kens 
O v e r v i e w 
FIGURE 1 
IsoeledronicSiOaridPNspedes 
SK>V 
ο ο 
0 \ ,Ο" 
ΝΗ2 
H2N 
NH2 V " 2 
u 
NH2 
HgPN*+ 
HtzP^N» 
Justin Uebig 
Friedrich WöHer 
(S1O2)» 
Ο 
l 
I 
HN 
I 
(HPN2>x 
FIGURE 2 
The product pattern of the ammonolysis or PCI5 
substitution 
c 
ο 
η 
d 
e 
η 
s 
a 
t 
i 
ο 
η 
PC! 5 - PCI3NH2ICI - [PCt2(NH2)2lCI - IPC!(NH2)3]CI- [P(NH2)41CI 
ι ι I 
[NPCyn 
lNP(NH2)da 
cydophosphazenes 
[KPNHJx 
phospham 
Main Group Chemistry News. Volume Ζ Number 4 
O v e r v i e w 
tion number of 7 is realized, resembling a TH-analo-
gous structure (Fig. 4). A n essential feature for the 
arrangement of the cations in both structures is the 
formation of N-H.. . .X hydrogen bonds. 
The reaction of the tetraaminophosphoni-
urn ion with phosphorus pentachloride gives access to 
doubly branched phosphazenes (Equation 4) [6]. 
[P(NH 2 ) 4 ]* + 4PC15- » [P(NPC13)4]* + 8HC1 (4) 
By the influence of bases, the tetraaminophosphoni-
urn salts condense to triaminophosphazo-tri-
aminophosphonium salts (Equation 5) [6J. 
base 
2[P(NH 2) 4]+ » [ ( N H 2 ) 3 P N P ( N H 2 ) 3 ] ^ N H 4 * (5) 
According to the X-ray structure determination, both 
salts contain the tetraaminophospnonium ion. In the 
cation, phosphorus and nitrogen form a markedly dis-
torted tetrahedron, with a P-N distance of 160.7(2) 
pm being the shortest P - N H 2 bond ever reported. 
In the iodide, a CsCl analogous coordina-
tion of cations and anions is found (Fig. 3) [10]. 
Contrary to this, in IP(NH 2) 4]C1, a mutual coordina-
Thermal condensation of [P(PNH2)4JX-salts leads to These compounds are also obtained by het-
phosphorus-nitride-imides with different hydrogen erogenous ammonolysis reactions (Equations 6 and 7) 
content, such as H P N 2 or H P 4 N 7 [10]. of pure and crystalline P3N5 [11]. 
58Q°C;14d 
P3N5 + N H 3 > 3HPN 2 (6) 
820°C;14d 
4P 3 N 5 + NH 4 C1 » 3 H P 4 N 7 + H C 1 (7) 
Both compounds are built up by three-dimensional 
framework structures of corner sharing PN4-tetrahe-
d i a [ l l J. 
The structure of H P N 2 [5], which is isoelec-
tronic to S i0 2 , corresponds to the ß-cristobalite type 
(Fig. 5), the high temperature modification of S i0 2 . 
The structure of H P 4 N 7 can be regarded as a 
shear variant of the H P N 2 structure, which results by 
eliminating one N H 3 from four formula units of 
HPN 2 . The valences of the P-N framework are satu-
rated by nitrogen which are bonded to three phos-
phorus atoms according to the formula 
£[P 4WN 5p 2lN 2Wi 
The hydrogen-free phosphorus(V) nitride 
P3N5 is obtained in a pure and microcrystalline form 
by reacting (PNC1 2 ) 3 w i t h ammonium chloride, 
according to Equation 8 [11]. 
(PNC1 2) 3 + 2NH 4C1 
760° C; 2d 
P 3 N 5 + 8HC1 (8) 
The reaction is carried out in sealed glass ampules 
and the size of the batch is limited by the pressure 
caused by formation of hydrogen chloride. The 
decomposition of tetraaminophosphoniumchloride 
(Equation 9) [7] is without these limits. 
L300°C;10- 3 bar 
3[P(NH 2) 4]Ct » P 3 N 5 + 3NH 4C1 + 4 N H 3 (9) 
2.750°C;lbar 
10 Volume 2. Number 4, Main Group Chemistry News 
O v e r v i e w 
FIGURE 3 
The coordination of the 
tetraaminophosphonium ion in [P(NH2)4]I 
FIGURE 4 
The coordination of the tefraaminophosphonium ion 
by chloride in [P{NH2)4]CI. 
According to the formula i i^W^PJN^ 3 ! ] , c o n t a i n s 
two types of nitrogen atoms, with 3/5 bonded to two phos-
phorus atoms and 2/5 bonded to three atoms. The structure is 
dominated by a stacking disorder, as demonstrated by 
HRTEM investigations [11], 
By reaction of P3N5 with L i 3 N ternary phosphorus, 
nitrides with P-N anions are accessible. 
In the quasi-binary system Ü3N/P3N5, LiPN 2 is the 
compound with the highest Ρ content. It has a three-dimen­
sional framework structure ^[ΡΝ^Ί which is isotypic to 
HPN 2 or ß-cristobalite [12], In L i 1 2 P 3 N 9 , the anion [P 3 N 9 ]U-
(Fig. 6) corresponds to the cyclotrisilicate anion [S13O9]6' 
[13]. In L17PN4, isolated [PN4]7*tetrahedra isoelectronic to 
ortho-silicate anions are found (Fig. 7) [14]. A compound 
containing the anion [H4PN4] 3 ' isoelectronic to H4SLO4 is 
obtained from the reaction of P3N5 and CsNH 2 [15]. 
Li5P2N5 contains no ÜP2N5 5*] layers, but isolated 
[P4N10]10" anions have been found (Fig. 8) [16]. A compound 
containing the anion [ H ^ N J Q ] * ' has been obtained from the 
reaction of P3N5 and N a N H 2 [17]. These anions are isosteric 
to molecular phosphorus pentoxide P4O1Q or to silicic esters 
S14O5 (OR) 4 with bulky substituents R. A n analogue to layer-
silicates has not been found yet. 
A n arrangement analogous to chain-silicates is real-
ized in the calcium phosphorus nitride Ca2PN3 (Fig. 9) [18]. 
The synthesis is analogous to that of the Li-salts by reacting 
the basic metal nitride C a 3 N 2 with the acidic non-metal 
nitride P3N5 (Equation 10). 
FIGURE 5 
The structure of HPN 2 
FIGURE 6 
The structure of the anion PaNy 1 2 - in L1J2P3N9 
Alain Group Chemistry News, Volume 2, Number 4 ii 
O v e r v i e w 
2Ca 3 N 2 + P3N5 
800°C;14d 
»1 3Ca 2PRj (10) 
Because most of the ternary phosphorus nitrides con-
tain structural analogues to the silicates, i t seemed to 
be a promising task to search for P -N frameworks 
with zeolite-like structures. 
The synthesis of a P-N zeolite succeeded by 
treating P3N5 and volatile metal halide with ammo-
nia at 640° C (Equation 11) |19]. 
4P 3 N 5 + 4 N H 3 + 5ZnCl 2 
640° C 
Z n 5 H 4 I P 1 2 N 2 4 ] C l 2 + 8HC1 (11) 
In a subsequent reaction with additional zinc chlo-
ride, a complete exchange of the hydrogen is possible 
(Equation 12). 
Z n 5 H 4 [ P 1 2 N 2 4 l C l 2 + 2 Z n C 1 2 
700° C; 3d 
Z n 7 l P 1 2 N 2 4 ] C l 2 + 4HCI (12) 
The cubic compound is isostructural to sodalite, 
Nag[Al6Si$0 2 4]Cl 2 . The alumosilicate framework is 
replaced by a nitrido phosphate framework (Fig. 10). 
I n the center of the ß-cage, a Cl~ ion is found which 
is tetrahedrally surrounded by metal cations Z n 2 + . 
A more elegant method for preparation of 
P-N sodalites is the direct reaction of metal dihalides 
with phosphorus nitride iminde (Equation 13) [11]. 
5MX 2 + 12HPN 2 
700°C; 2d 
Ρ M 5 H 4 [ P 1 2 N 2 4 ] X 2 + 8HX (13) 
A large number of compounds has been realized in 
this manner containing, for example, M g 2 + , Z n 2 + , 
Co 2 * , Ni 2 +, C u 2 + or Pb 2* as cations and F~, C I ' , Br" 
or Γ as anions. 
A striking feature of several P-N sodalites is 
their intense color. The cobalt and nickel containing 
compounds are blue, the iron containing brown and 
Cr and T i containing materials are green. 
A P-N sodalite without a central halide ion 
is accessible by reaction of zinc nitride with phospho­
rus nitride (Equation 14) [20]. 
2 Z n 3 N 2 + 4 P 3 N 5 
750°C; 7d 
Zn6[P 1 2 N 2 4 ] (14) 
The P-N framework in this compound is the same as 
i n Ζ η 7 [ Ρ ι 2 Ν 2 4 ] 0 2 , but the zinc atoms are disordered. 
Indications have been found that Znä[P 1 2N 2 4] might 
be useful as a hydrogen storage material. 
As shown in this overview, several examples 
for the structural analogy between SMD and P - N 
compounds do exist. Typical silicate building blocks 
and the corresponding P-N isosteres show different 
formal charges, as Si04 4 '/PN 4 7 ' , SijO^I?^11' or 
Si0 2/PN 2- > but in ternary and higher compounds, the 
P-N substructures correspond to the respective sili-
cate structures. 
12 Volume 2, Number 4P Main Group Chemistry News 
O v e r v i e w 
FIGURE 7 
The structure of the anion PN47* in U7PN4 
FIGURE 8 
The structure of the anion P4N10 1 0" in lijofyNlO 
Using this structural analogy, i t should also 
be possible to obtain phosphorus nitrides analogous 
to nanoporous zeolites or layered silicates which 
might be materials with promising technical rele-
FIGURE 9 
The structure of the anion i i P N 3 4 " j in Ca2PN3 
vance. 
References and notes 
1. From W, Uwicki, "Wähler and Liebig—Briefe von 1829-1873 " 
J. Cromm Vertag, Göttingen, p. 63 (1982). 
2. "When chlorophosphorus and ammonia are brought together, much 
ammonium chloride is formed. This necessitates the formation of 
amides; the composition of chlorophosphorus is such however, that 
no simple amide can form.'' 
3. A. Schrnidpeter et al., Z. Natwforxh., B24,799 (1969) and 
literature cited there. 
4. M.C Gerhardt, Aim. Chm. Fhys., 18,188 (1846); C.R. Acad. Sci.t 
22,858(1846). 
5. W. Schnick and J. Lücke, Ζ. Anorg. Aifc. Chem., 610,21 (1992). 
6. A. Schrnidpeter and C Weingand, Angew. Chem., 81,573 (1969); 
Angew. Chem. Int. Ed. End., 8,615 (1969). 
7* S. Korstmann and W. Schnick, unpublished results. 
8. A. Schrnidpeter and C Weingand, Angew. Chem., 80,234 (1968); 
Angew. Chem. Int. Ed. EngL, 7,210 (1968). 
9. W. Schnick et aL, Angew. Chem., 106,818 (1994); Angew. Chem. 
Int. Ed. Engl, 33,785 (1994). 
tO. S. Horstmann and W. Schnick, Z. Natwi/orscft., (in press). 
11. W. Schnick, Angew. Chem., 105,846 (1993); Angew. Chem. 
Int. Ed. Engl., 32,806 (1993). 
12. W. Schnick and J. Lücke, Z. Anorg. Alfe. Chem., 588,19 (1990). 
13. U . Berger and W. Schnick, unpublished results. 
14. W.Schnickar-lJ.UfckeJ.SoWSt^ 
15. H. Jacobs and F. Gotinski, Z. Anorg. ABg. Chem., 620,531 (1994). 
16. W. Schnick and U . Berger, Angew. Chem., 103,857 (1991); 
Angew. Chem. Int. Ed. EngL, 30,830 (1991). 
17. H. Jacobs et al., Z. Anorg. A%. Cherry 620,1213 (1994). 
18. W. Schnick and V. Schultz-Cotilon, Angew. Chem., 105,308 
(1993); Angew. Chem. Int. Ed. EngL, 32,280 (1993). 
19. W. Schnick and J. Lücke, Angew. Chem., 104,208 (1992); 
Angew. Chem. Int. Ed. Engl, 31,213 (1992). 
20. F. Wester and W. Schnick, unpublished results. 
FIGURE 10 
The ß-cage of Ζ ^ Ρ ^ Ν ^ Κ ^ 
Main Group Chemistry News, Volume 2, Number 4 13 


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P-N-Compounds. From the Single Tetrahedral Cation to Framework Structures

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