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Four-Membered Phosphorus-Nitrogen-Metal Heterocycles with Zwitterionic Structure.

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Four-Membered Phosphorus-Nitrogen-Metal Heterocycles with Zwitterionic S t r u c t u r e [ * * ]
By Edgar Niecke, Ruiner Kroher, and Siegjiiied Pohl"]
The synthesis of four-membered heterocycles from aminesilylated aminoiminophosphanes and metal halides (a) is
limited to a small number of elements due to the u-elimination
of many of the Lewis acids (b)['l.
Y
A
P
'N-
-N'
\-'
+
RX
I5
x "-2
(a)
R
-N-P=N-
+
EX,,
(R = SiMe3)
(b)
R X
EXp2 + -N-P=NX
In the reactions of h5-phosphorus-nitrogen ylides with EX,
we observed cyclizing halosilane elimination['] [in analogy
with (a)] as well as adduct formation, in place of (b), to
Q
B
yield the cyclic zwitterions ( 4 ) which have a PNzE skeleton.
As is exemplified by the reaction of bis(trimethylsily1)aminobis(trimethylsily1imino)phosphorane (1) with main
group and transition metal halides, this reaction allows access
to novel phosphorus-nitrogen-metal heterocycles ( 4 c-e)rgl
and also the stabilization of rarely occurring coordination
numbers of the metal atoms (Table 1 : ( 4 a , d)).
R = SiMe3
P;EXnQ
TR
YRZ
X-P&N-R
E X n = SnCl,, AlC13,
FeC13, T i C 4 , NbCS
f2)
R-N-EX,,
(4)
T U S [ ~ ] ,the electrophilic phosphorus being then stabilized by
chloride migration.
The composition and constitution of compounds ( 4 ) as
four-membered PN2E rings with zwitterion structure have
been established by elemental analysis, molecular weight determinations, mass spectrar4],('H,31P)-NMR and characteristic
IR data (Table 1) and by X-ray structure analysis in the
case of ( 4 d ) .
Whereas the coordination of the metals in ( 4 a , b , e )
(CN = 3,4,6) results, as expected[5],in magnetic equivalence
of the trimethylsilyl groups bound directly to the ring, in
( 4 d ) these substituents are anisochronous. These findings,
which were confirmed by the I3C{lH}-NMR spectra of
( 4 d)L6],are in accord with a trigonal-bipyramidal coordination
of the titanium atom with one N atom being in the axial
and the other in the equatorial position. 'H- and 13C{'HJNMR measurements at high temperatures show that the two
pertinent %Me3 groups equilibrate at 37(2)"C independently
of the concentration of the solution['! This speaks in favor
of an intramolecular process occurring at the titanium atom
I01
We suspect that the heterocycles are formed by intramolecular ring closure from the intermediates (3) which are themselves produced by a four-centered reaction. The first step
of the reaction possibly involves a stage with a highly reactive
phosphenium species having a triply coordinated phospho-
Fig. 1. Molecular structure of ( 4 d ) (without the H atoms; vibration ellipsoids
are shown with a probability of 50 %).
Most important bond lengths [pm] and angles ["I:
Ti-CIl 225.1(3),Ti-CI2 223.5(3), Ti-C13 21Y.7(3), Ti-N2 201.0(5), Ti-N3
204.8(5), P-N2 161.3(5), P-N3 15Y.7(5), P-N1 162.2(5),P-C14 203.6(3);,
CII-Ti-CI2
Y2.1(1),Cll-Ti-C13
102.0(1),CI1-Ti-N2
Y0.1(2), Clt-TiN3 155.8(2), C12-Ti-CI3
108.7(1), CI2-Ti-N2
140.7(2), CI2-Ti-N3
Y0.3(2), CI3-Ti-N2
109.2(2), Cl3-Ti-N3
100.1(2), N2-Ti-N3
73.1(2),
Ti-N2-P
Y4.8(2), Ti-N3-P
Y3.8(2), N2-P-N3
97.8(3).
Table 1 , Properties and spectroscopic data of the zwitterions ( 4 )
-
(4al
(46)
(4 c)
(4d)
SnI3'
AV4'
FeI4'
Ti'5'
17.7 [c]
26.3
[d]
18.0
(4e)
NbI6'
28.1
0.24 (0.45 Hz)
0.27 (0.65 Hz)
cdi
0.53 ([el)
0.57 ([el)
0.62 (0.65 Hz)
543
117
132
>110 (dec)
> YO (dec)
white
white
red-brown
orange
558
> 130 (dec)
yellow
0.51
0.54
Cdl
0.49
1155,1108
1147, 1089
1135, 1080
1100, 1058
530
556
535
0.56
1071, 1002
[a] 30 percent solution in CH2C12 with TMS as internal ('H-NMR) or H 3 P 0 4 as external standard ("P-NMR) at room temperature. [b] Nujol mull.
[c] Jp11'~119sn= 191.6, 197.1 Hz. [d] Substance is paramagnetic. [el Not resolved.
[*] Priv.-Doz. Dr. E. Niecke, DipL-Chem. R. Kroher
Anorganisch-Chemisches lnstitut der Universitat
Tammannstrasse 4, D-3400 Gottingen (Germany)
Dr. S . Pohl
Fakultat f i r Chemie der Universitat
Universitatsstrasse, D-4800 Bielefeld 1 (Germany)
[**I Part 14 of Studies on Phosphazenes with Coordination Numbers of
2 and 3.-Part 13: E. Niecke, H . G . Schafer, Angew. Chem. 89, 817 (1977);
Angew. Chem. Int. Ed. Engl. 16, 783 (1977).
864
(Berry pseudorotation or turnstile rotation) as has been suggested in the interpretation of exchange phenomena with pentacoordinated Dhosvhorus['].
The titanium compound ( 4 d ) crystallizes monoclinically,
space group P21/n; a=943.9(1), b= 1718.3(3),c= 1724.2(3)pm;
p=92.12(1)"; V=2795.106pm3; 2 = 4 . Refinement with the
factors from 3866 observed reflections
[Z>1.968o(l)] gave an unwejghted R value of 7.0%
I
&
Angew. Chem. lnr. Ed. Engl. I6 (1977) N o . 12
(R,.,=6.5 %). Figure 1 represents the molecular structure
of ( 4 d ) and shows the vibration ellipsoids of the atoms (the
positions of the H atoms could not be localized).
The four-membered ring formed from the Ti, N2, P and
N3 atoms is planar within the limit of error. The coordination
of the titanium atom can be described as a distorted trigonal
bipyramid. The two ring nitrogen atoms occupy different positions (axial and equatorial) which confirms the findings
of NMR spectroscopy. The chlorine atoms bound to the
titanium also have larger coefficients for the anisotropic temperature factors than the chlorine atom bound to the phosphorus; these findings are probably due to a dynamic defect
as has been found in solution.
complexometric titration and as reagents for solvent extraction
and spectrophotometric determination of numerous metal
ions. They act as monovalent tridentate chelate ligands. Their
bonding to the metal ion might be largely determined by
a synergicd+n* electron transfer from the metal to the azopyridine systeml2'. Expressed in terms of valence bonds, a redox
relationship ( B ) is superposed upon the donor/acceptor relationship ( A ) between ligand and metal ion.
n
Y,N
c)
'
Experimental Procedure
A solution of 7.3g (0.02mol) ( I ) in 10ml toluene is added
dropwise with stirring under an atmosphere of N2 to a suspension of 0.02 mol of the metal halide in 20ml toluene at room
temperature. The reaction mixture is then stirred for 5 h.
( 4 4 b ) : The solvent is evaporated off at 4OoC/0.1 torr
and the residue is sublimed twice at 7S°C/0.1 torr ( 4 a ) or
85°C/0.1 torr ( 4 b ) . Yields 7.8g (70%) ( 4 a ) and 4.Sg (45%)
(4b).
(4 c ) :The reaction solution is allowed to stand until crystallization occurs (ca. 80 h). A single recrystallization affords
7.6g (72 %) ( 4 c ) .
( 4 d , e ) : The reaction solution is cooled to -20°C when
( 4 d ) and ( 4 e ) crystallize out. Recrystallization gives 6.8 g
(55 %) ( 4 d ) and 4.6g (37 %) ( 4 e ) .
M-N
/
fBI
(A)
M = M e t a l equivalent
Like metal ions, trivalent phosphorus can also simultaneously accept and donate electrons. Indeed, in principle,
(2) and ( 3 ) react with chlorophosphanes ( I ) in the same
way as with metal ions, i.e. as tridentate ligands. Owing
to the higher reducing power of P"', however, the oxidative
addition in the sense of formula ( B ) is realized, and the
bicyclophosphoranes (6) and ( 7 ) are formed.
A
RzPCl +
Received: September 9, 1977 [Z 841 IE]
German version: Angew. Chem. 89, 902 (1977)
CAS Registry numbers:
(1),52111-28-1; (4~),64413-72-5;(4b), 64413-71-4; ( 4 ~ ) ,64413-70-3; (4dJ,
64413-69-0; (4e), 64413-68-9; SnCI,, 7772-99-8; AICl3, 7446-70-0; FeCI,,
7705-08-0; TiC14, 7550-45-0; NbCI5, 10026-12-7; I3C, 14762-74-4
HO
[I1 Review: E. Niecke, 0.J . Scherer, Nachr. Chem. Tech. 23, 395 (1975).
P I With the formation of heterocycles of the type
RN =P(X)-N(R)-E(X.-2)-$4R
(R=SiMe3; EX.=BC13, SiCI4):
E. Niecke, R . Kroher, unpublished.
131 The formation of the heterocycle
e
e
R2N-P(Me)-N(R)-SiMe2-N-AlCl~
as a side product which is
isomeric with ( 4 6 ) speaks in favor of this; this reaction can be
explained by the migration of methanide from (2 J.
141 MS (70eV) in m / e : M (based on the most abundant isotopic species)
555 (2%) ( 4 a ) , 499 (2%) (4b), 526 (1 %) ( 4 c J ; {M-EX., -Me} 350
(100%) ( 4 a , b , c ) .
151 An almost planar arrangement of the ring nitrogen is assumed.
161 @'3C)=5667, 6.34, 3Jcp=2.0, 2.8Hz (NSiC3); 3.28, 3JCp=3.6Hz
(-N(SiC&); 30 percent solution in CDC13 (TMS int.) at room temperature.
171 2 to 30 percent solution in CICH2CH2CI ('H) or CDC13 ("C).
PI a) R . S. Berry, J. Chem. Phys. 32,933 (1960);b) P . Giflespie,P . Hofmann,
K . Klusacek, D. Marquarding, S . Pfohf, F . Ramirez, E. A . Tsofis, I . Ugi,
Angew. Chem. 83, 691 (1971); Angew. Chem. Int. Ed. Engl. 10, 687
(1 971).
191 Heterocycles with the skeleton PN2E'CN', E =A[''', Sd6' are known:
a) H . Schmidbaur, K . Schwirten, H . H . Pickel, Chem. Ber. 102, 564
(1969); b) 0. J . Scherer, G . Schnabl, Inorg. Chim. Acta 19, L 38 (1976).
- Ha
__*
Hd
(3)
The reactions most likely proceed via the substitution intermediates ( 4 ) and ( 5 ) . The second step is then [4+ I]cycloadwhich is normally restricted to certain heterodition at Pnr[31,
dienes, but in this intramolecular version is also observed
51.
with the azopyridine
Nf-(2-Pyridyl)benzilmonohydrazone (8) contains a sevenmembered chain having the same functionality as in ( 2 ) but
with a 1,s-shifted proton. Like (2) it forms metal chelates161
and reacts with ( I ) to give bicyclophosphoranes (9).
/)-CsH5
Intramolecular Oxidative Addition of Azopyridine to
Phosphorus(rrr)I 1
By Aljred Schmidpeter and Josef Helmut Weinrnaier['l
1-(2-Pyridylazo)- and l-(thiazol-2-ylazo)-2-naphthol,( 2 )
and ( 3 ) , called PAN and TAN, are used as indicators for
r] Prof. Dr. A. Schmidpeter, Dip[.-Chem. J. H. Weinmaier
Institut fur Anorganische Chemie der Universitat
Meiserstrasse 1, D-8MM Miinchen 2 (Germany)
Angew. Ciiem. Int. Ed. Engl. 16 (1977) No. 12
n
The upfield shift of the 31P-NMR signals (Table 1) confirms
that the phosphorus in (6), ( 7 ) , and ( 9 ) achieves pentacoordination. The bicyclic should be planar, i. e. meridionally incorporated in the trigonal-bipyrimidal configuration. This is supported by the fact that the substituents on the phosphorus
when R' =RZ are equivalent in the 'H-NMR spectrum and
that their signals are split with ' * ' J l p ~ coupling constants
865
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