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Homopolar and Heteropolar Halogeno Esters of Phosphorus Arsenic and Antimony.

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Structure and Magnetism of Ternary Fluorides
D. Babel, Tubingen (Germany)
The magnetic behavior of transition-metal ions M2’ =
Mn2;-, C O ~ ’Nil
, r, and Cu2 in ternary fluorides AMF3 and
A2MF4 ( A : ~
= alkali-metal ion or TI'^) is related to the structure of the compounds. Compounds AMF3 crystallize in
rhombic, cubic, or hexagonal perovskite lattices depending
on the Goldschmidt tolerance factors. Hexagonal lattices are
present, above all, in the Cs compounds CsMnF3 (hexagonal
BaTi03 type; also RbNiFx), CsCoF3 (BaRu03 type), and
CsNiF3 (BaNi03 type). The number of MFb octahedra
sharing faces increases in the order given. Except forNa2CuF4
(monoclinic, individual type), compounds A2M4 are formed
only when A = K, Rb, TI, or Cs; they occur in the tetragonal
K2MgF4 type, with the exception that cesium fluorides
C S ~ M Fcrystallize
~
in a hexagonal structure, details of
which are not known.
The magnetic properties range from antif’erromagnetism
(KMF3) through normal paramagnetism (CsMF3, A ~ C U F ~ )
to strong ferrimagnetism (RbNiF3), and can be explained
by considering the distances and coordination relations in
the lattices. In particular, consideration of superexchange [ * I
and its dependence on the electron configuration of the cation
and the arrangement of ions in the crystal permits qualitative
interpretation of the magnetic properties. Thus, cases of 3 - ,
2-, 1-, and 0-dimensional superexchange can be differentiated
which, in conjunction with the dependence on M-F distances and M-F-M angles, account for the variations in
magnetic behavior.
[Lecture at Erlangen (Germany), on February loth, 19661
[VB 982.’289 IE]
German version: Angew. Chem. 78, 451 (1966)
[*I Superexchange is the magnetic interaction between paramagnetic cations by means of intermediary anions.
Homopolar and Heteropolar Halogeno Esters of
Phosphorus, Arsenic, and Antimony
L. Kolditz, Berlin (Germany)
Compounds of pentavalent phosphorus, arsenic, and antimony that carry both halogen and OR groups (R = alkyl or
aryl) on the central atom, like the analogous simple pure and
mixed halides, appear in homopolar and salt-like forms.
In polar solvents equilibria are established between these
two forms, the homopolar form undergoing association by
means of halogen or OR bridges even in relatively dilute
solution (e.g. 0.01 M in CH3CN). The behavior of chloro(ethoxo)antimony compounds is typical, leading to equilibria
according to (L = solvent) :
2 SbCln(OR)s-,.L
=+[SbCln+1(0R)~-nLz]++
[SbC1n+l(OR)~-nl- (a)
The situation is, however, complicated by exchange reactions between CI and OR.
Alkoxofluorohydroxoarsenic compounds behave similarly;
in the forms HO(RO)3AsF and HO(R0)2AsFz they show a
strong tendency to condense, with elimination of OH groups
and formation of oligomers containing As-0-As linkages.
On reaction with KOCH3 in C2C13F3, arsenic pentafluoride
gives the compound AsF40CH3 as well as K[AsF6]. The
reaction mechanism is interpreted as :
Compounds P(OR)2F3 and [P(OR)J][PF~]are formed by
exchange of Cl ligdnds in PC12F3 (homopolar) and
[PCId][PF6] (salt-like) for OR groups. I n polar solvents ( e x .
CH3CN) the homopolar substancc is transformed into the
salt-like one in an equilibration of the above type. On decomposition of the salt-like compound the cation yields
OP(OR)3.
[Lecture at Mainz (Germany) o n January 22nd, 19661
[VB 979,’286IE]
German version: Angew. Chem. 78, 451 (1966)
Chemistry of Phosphorus, Arsenic, and
Antimony Halides
L. Kolditz, Berlin (Germany)
We have studied the reactions of phosphorus, arsenic, and
antimony halides with polar solvents. PFs, AsF5, and SbFS
form adducts with CH3CN, and these dissociate in aceto.
nitrile according to Eq. (a) (A = P, As, Sb):
+
2 AF5.CHKN + [AF4(CH3CN)2IA [ A h -
(a)
An analogous formulation holds for S ~ C I S - C H ~ CThe
N . dis-
sociation can be demonstrated by conductivity measurements
and hydrolysis experiments. Hydrolysis occurs only at the
cation for A := p, As, the anions remaining unchanged.
This is true also for the compound PFs.N(CHd3, but
AsFg,N(CH3)3 occurs only in the “homopolar” form and
is unaffected by moisture; the arsenic compound is not even
wetted by water.
A solution of chlorine in AsC13, which contains the solvate
AsCI3-Cl2 but no ASCIS,is a very strong chlorinating agent.
Arsenic and antimony compounds that contain a CF3 group
as well as halogen (general formula AXz(CF3)3) are more
stable than the corresponding simple halides.
[SbBrsl- ions decompose in CH3CN according to Eq. (b).
The structure of [SbBr& may thus be represented by the
[SbBr,j-
--f
SbBr3 + Br-Brz-
(b)
formula [SbBrd.Br$. Easy loss of bromine occurs also with
ShBr5,O(C2H5)2, which can be prepared only with an excess
of antimony (e.g. Br:Sb = 4.7: 1). SbBrS, like ASCIS, is not
known in the pure form.
The system SbC15, SbFS contains associated apolar and also
polar forms. The most stable compound is SbCbF, which is
tetrameric in the solid state: distorted SbC14 tetrahedra are
linked by asymmetrical fluorine bridges (varying Sb-F
distances).
All the compounds mentioned tend to exchange halogen.
The equilibria occurring in solution are dependent o n solvent,
concentration, and temperature, and the halogen-transferring
action of the apolar substances differs from that of the saltlike forms, so that halogenation can be readily controlled.
[Lecture at Aachen and Frankfurt/Main (Germany),
on January 21st and 27th, 19661
P B 980/287 I € ]
German version: Angew. Chem. 78, 452 (1966)
Structures and Reactions of the Products of
Reaction of Hydrogen Cyanide with
Hydrogen Halides
E. Allensfeiri, A. Schmidt, and V. Beyl, Stuttgart (Germany)
2 AsFs
AsF4’
AsF++ AsF+ KOCH3 + AsF40CH3
i+
+ K+
(b)
Equilibrium (c) was found when AsF3 was used as solvent:
( A s F ~ O C H ~+) ~[ A S F Z ( O C H ~ ) ~ ] [ A ~ F ~ ~
[AsFz(OCH3)21+
+ [Ash]-
Angew. Chem. internat. Edit. J Vol. 5 (1966)
1 No. 4
(c)
Structural investigation of the “sesquihdiides of hydrocyanic
acid,” 2 HCN.3 H X (X = CI or Br), mostly by infrared
spectroscopy but also by chemical methods, has shown that
they are N-(diha1ogenomethyl)formamidinium halidesC21,
[HXZC-NH-CH-NH~]+X-, in accordance with the view
of Gattermann and Schnitzspahn (11.
425
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heteropolar, halogen, antimony, homopolar, esters, arsenic, phosphorus
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