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N P-Organometalated Phosphine Imines from Aminophosphines.

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solvatochromy, which indicates relatively great participation
of the resonance structure (6) in the ground state.
Reaction of o-(4), R3 = CH3, with secondary amines affords
the o-quinone methide imines (7).
Cpd.
I
An etheral solution of ( I ) is smoothIy metalated by n-butyllithium in hexane at 0 "C. Reaction of N-phosphinyllithium
amide (2) with chlorotrimethyl-silane or -germane affords
di-(tert-butyl)phosphinyltrimethylmetal amides (3).
R
I
I
I
I
I
I
I
I
I
I
The N M R spectra of (7), RI = Rz = CH3, are temperaturedependent. For a solution in liquid SO2 at -4OOC the
signal due t o the NCH3 protons appears as a doublet (T =
2.28 and 2.75), but at 37 O C as a singlet (T = 2.48). The NCH3
signal is also split (T = 2.77 and 3.01) in the N M R spectrum
of o-(4), Rl = R 2 = CH3 (liquid SO2, -4OOC). Most of the
compounds ( 4 ) and (7) fluoresce strongly in the solid state.
When o-(3), R = C6H5, is treated with K tert-butoxide in
dimethylformamide a deep blue solution results. The oquinone methide imine that is obviously formed could not be
isolated but was proved t o exist by cycloaddition of phenyl
isocyanate and phenyl isothiocyanate.
(30): M
Si; b.p. 39-40°C 1 torr; m.p. -4 t o -2°C; yield
80 %; IH-NMR spectrum, J(3IPCCH) = 11.0, J(3IPNSiCH)
= 0.6 Hz.
(36): M Ge; b.p. 49-50 "C, 1 torr; m.p. -6 t o -4°C; yield
72 %; IH-NMR spectrum, J(3IPCCH) = 11.0, J(31PNGeCH)
= 0.3 Hz.
:
2:
Further metalation of compounds (3) [(3a) at room temperature; (36) at -40 "C] in ether with n-butyllithium affords
compounds (4) whose existence is proved by treatment with
chlorotrimethylsilane or -germane.
November 1 1 , 1967 [ Z 640IE1
German version: Angew. Chem. 80,38 (1968)
Received: September 14, 1967; revised:
[ * ] Prof. Dr. R. Gompper and Dip1.-Chem. H.-D. Lehmann
Institut fur Organische Chemie der Universitat
8 Munchen 2, Karlstr. 23 (Germany)
[I] R. Gompper and E. Kutter, Chem. Ber. 98, 1365 (1965).
[2] R. Gompper, E. Kutter, and H.-U. Wagner, Angew. Chem.
78, 545 (1966); Angew. Chem. internat. Edit. 5, 517 (1966).
[3] A. Baeyer and V. Villiger, Ber. dtsch. chem. Ges. 37, 591
(1904).
[4] H. Herlinger, Angew. Chem. 76, 437 (1964); Angew. Chem.
internat. Edit. 3, 378 (1964); G. Ege, Angew. Chem. 77, 723
(1965); Angew. Chem. internat. Edit. 4,699 (1965); R. K. Smalley
and H . Suschitzky, Tetrahedron Letters 1966, 3465; E. M.
Burgess and L. McCuIlagh, J. Amer. chem. SOC.88, 1580 (1966).
[5] E. M . Burgess and G. Milne, Tetrahedron Letters 1966, 93.
(6u): M = Si, M' .- Ge; sublimes at ca. 9O"CjO.l torr; yield
87 7;; IH-NMR spectrum, J(3lPCCH) = 14.3, J(31PGeCH)
= 4.4, J(31PNSiCH) = 0.4 Hz.
(6b): M = Ge, M' = Si; sublimes at ca. 8O"C/O.l torr; yield
75 %; IH-NMR spectrum, J P l P C C H ) = 11.9, J(31PSiCH) =
2.2, J(3IPNGeCH)
N,P-Organometalated Phosphine Imines
from Aminophosphines
By 0. J . Scherer and G. Schieder [*I
N-Organometalated phosphine imines can be prepared from
alkyl- or aryl-phosphines and organometal azides [I]. O n
treatment with a n excess of ammonia in ether at ca. -50 OC
di-(tert-buty1)chlorophosphine [21 [b.p.
49-50 "Cj5 torr;
J(31PCCH) = 12.0 Hz] gives an 81 % yield of aminodi-(tertbuty1)phosphine (1) as a water-clear liquid that is sensitive
to oxygen and to moisture and does not condense t o give
([(CH3)3C]2P)2NH when kept for four weeks in a closed
vessel.
[(CH3)3C]zP-CI
+ x NH3
+
=
0 Hz.
Although the IH-NMR spectrum of the phosphine imine
(60) with its P-GeIN-Si
bond before as well as after
sublimation gives no indication of existence of the isomer
(6b), the compound (6b) slowly rearranges to (60) during
sublimation [the isomer mixture contains ca. 25 % of (6a)
and 75 % of (6b) after the first sublimation; ca. 60 % of (60)
and 40 % of (66) after a second sublimation; identified by
I H-NMR spectroscopy].
Heating at 120-130°C for several hours is necessary for
quantitative conversion of (66) into (6a). Keeping a benzene
solution of the isomer mixture at room temperature for
several days does not lead to enrichment of (6a).
+
[(CH,)~CIZP-NH~ NH4C1
(1)
(I): b.p. 33-34OC/2 torr; m.p. -1 t o + l O C ; 1H-NMR
spectrum (Varian A-60, 60 MHz; 10 % solution in benzene;
tetrarnethylsilane as external standard), J(3IPCCH) =
11.0 Hz.
Angew. Chem. internat. Edit. / Vol. 7 (1968) I No. I
The two phosphine imines ( 6 ) are readily soluble in ether,
petroleum ether, and benzene; they react with CC14 [as
Compounds (3a) and (60) react t o form
does (3)l.
[(CH3)3C]2P(Cl)=N-Si(CH3)3 (b.p. 42 O C / l torr; m.p.
75
x;
--13 ‘C; yield 90
1H-NMR spectrum: J(31PCCH) = 17.3,
J(31PNSiCH) == 0.5 Hz; IR: P-N 1340 cm-I). (60) has a
strong P-N band at 1320 cm-1 in its I R spectrum.
That the new class of N,P-orgdnometalated phosphine
imines (6) is formed by way of the intermediate addition
product (5) and not by a rearrangement of MirlmelisArbuzov type involving the intermediate (7) was proved by
our experiments [(h)M = Si
(CH&GeCI; (4b) M =
Ge + (CH3)3SiCI]; if (7) had been formed, then the same
+
product or mixture of isomers would have resulted in the
two cases.
Compound ( 3 ) exists exclusively in the aminophosphine
form, this being proved by the I R spectrum (absence of a
P = N band) and by oxidation with sulfur.
Received: November 23, 1967
[Z 663 IE]
German version: Angew. Chem. 80, 83 (1968)
[ * ] Priv.-Doz. Dr. 0. J. Scherer and G . Schieder
Institut fur Anorganische Chemie der Universitat
87 Wiirzburg, Rontgenring 11 (Germany)
[l] J . S.Thayer, Organometal. Chem. Rev. I , 157 (1966); G .
Singh and H . Zimmer, ibid. 2, 279 (1967).
[21 W. Voskuil and J . F . Arens, Recueil Trav. chim. Pays-Bas 82,
302 (1963).
CONFERENCE REPORTS
Second International Meeting on Fuel Cells
held in Brussels (Belgium) on June 19-23, 1967
Some 350 participants attended this Meeting which was arranged by the Belgian Research Organisation S.E.R.A.I.
(Socitte d’Etudes de Recherches et d‘Applications pour
I’Industrie). They came from 22 countries and represented
190 firms and Institutes. This shows that fuel cells have not
lost their fascination as direct converters of chemical into
electrical energy. However, there has been no easing of the
difficulties connected with direct electrochemical oxidation,
particularly of organic fuels. The following report presents a
selection from the total of 5 5 papers.
1. Studies of the Course of Reaction
In porous electrodes, conversion o f the reactant gases takes
place near the electrolyte meniscus that is formed in the
pores of the electrode. Hawever, there is as yet no general
answer to the question whether the reaction route involves
(i) adsorption on the dry pore walls, (ii) surface diffusion to
those parts of the pores that are filled with electrolyte and
subsequent charge transfer, or (iii) diffusion through an
electrolyte film of about 1 thickness above the visible
meniscus before adsorption and charge transfer. To clarify
this problem, F. G. Will (General Electric Company, Schenectady, U.S.A.) had studied an enlarged model of a meniscus
covered with an electrolyte film. He covered a plane horizontal platinum foil, 4 0 c m long (the pore wall), with an
electrolyte layer of 0.5, I , or 2 mm thickness (the enlarged
electrolyte film). Hydrogen, as reactant gas, streamed over
the sulfuric acid electrolyte. The reference electrodes were
platinized platinum points dipping into the electrolyte
layer at distances of 2 c m from one another. It was thus
possible to measure, for each region, the potential and the
change in concentration by means of the resistance between
neighboring platinum points. The changes in resistance during the anodic oxidation were smaller by orders of magnitude than those calculated. The cause was found to be convection (which was demonstrated by means of pigment
particles) resulting from gradients in the surface tension.
Further, there was additional water transport through the
gas phase; this was shown very impressively when the surface of the liquid was covered with Teflon foil, water transport being morestrongly hindered than that of H2. Mathematical derivation of the polarization curve at limiting current
gave good agreement with experiment. Since the curves for
half-immersed electrodes and for technical gas-diffusion
electrodes showed the same characteristics, Will concluded
76
that the model provides a good picture of the pore function,
i.e. that a “film mechanism” is involved.
The effect of adsorption layers on electrode processes was
discussed in many papers. For instance, on platinum electrodes oxidation of CO in alkaline solution is hindered by
the oxygen adsorption layer formed from +SO0 mV (against
the reversible H2 electrode).
As H . Binder, A . Kohling, and G. Sandstede (Batelle-lnstitut,
FrankfurtIM, Germany) showed, a sulfur film, in contrast to
an oxygen film, is stable on platinum even in the region of the
H2 potential. Current curves, measured potentiodynamically,
show oxidation of the sulfur film to SO2 in aqueous potassium hydroxide at +450 mV (70 “C), in dilute sulfuric acid
at +650 mV (70°C), and in concentrated phosphoric acid at
+550 mV (150OC). When dipped into a solution containing
H2S, porous electrodes with Raney nickel as active component receive a defined sulfur film. A slow stream of reactant
gas was passed over such electrodes a t a gas pressure of
0.6 atm. The S sorbate had only negligible influence on the
oxidation of ethylene in dilute sulfuric acid or on that of C O
in alkaline solution, but the oxidation of CO in acid solution was accelerated; in experiments with a sulfur coverage
of 1 with a CO: H 2 0 mixture = 1:1 in 44 N H3P04 at 155 O C
the oxidation current was increased by a factor as high as 5.
However, with saturated hydrocarbons in acid or unsaturated
hydrocarbons in alkali the reaction velocity was diminished
approximately proportionally to the sulfur coverage. There
is as yet no explanation for the different behavior of carbon
monoxide and of saturated and unsaturated hydrocarbons.
The exchange current per unit area of electrode is often given
as a measure of the utility of an electrocatalyst. G. Richter
(Siemens AG, Erlangen, Germany) explained how the exchange current can be measured also for powder catalyst
present in powder form in the electrolyte if care is taken t o
achieve good electrical contact between the particles and a
lead electrode. The exchange current was calculated from the
initial current-potential curve and referred to the amount of
the catalyst. The specific surface in m2/g and values proportional to the surface, such as the double layer capacity
and the chemisorption capacity, have utility only for the
same support material. According to the method of preparation and after-treatment, values of the chemisorption capacity of unsintered Raney nickel (at potentials between 0 and
+10 mV) were found t o lie between 0.3 to 0.54 A s/g and for
the specific exchange current between 0.2 and 1.7 A/g; the
corresponding values for platinum black were 0.8 A s!g and
8 A,’g[Il.
Angew. Chem. internut. Edit. 1 Val. 7 (1968) / N o . I
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