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Tetrakis(dimethylphosphoniumbismethylide)dinickel a New Type of Cage Compound.

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C~~~Iolir.~trrircarbaldehpdc
atid cw-bmzoylbeiizyl cjriohrxat~ecurbos~~latr
Cyclohexene (250g, 3.05mol), benzil (250g, 1.19mol), and
R h 2 0 3(0.10g) are placed in a 2-1 steel autoclave previously
purged with nitrogen and are heated at 120 C with synthesis gas (20atm cold pressure). The synthesis gas pressure
is raised from 25 to 30 atm during the reaction. After 11
hours' reaction, distillation of the autoclave content affords
cyclohexanecarbaldehyde (146 g) boiling at 5&56 "C/17
torr and a-benzoylbenzyl cyclohexanecarboxylate (308 g,
80% yield based on benzil), boiling at 175-177"C/0.2 torr,
m.p. 100-101 "C (from light petroleum).
Received. May 23. 1973, revised: July 10, 1973 [Z 890 IE]
German version: Angew. Chem Xi. 911 (1973)
'H-NMR (ext.TMS,otherconditionsasabove)["I: I C H ~ P A
8.82ppm, d, J(HCPA) 8.1 Hz; sCHJPF~8.10, d, J(HCPs)
13.4; ICH~PC8.02, d, J(HCPc) 13.5; sCH~PB9.60, dd
(broad), J(HCP,) 16.1, J(HCPA) 2 13: rCH2Pc 9.48. dd
(broad), J(HCPc) 16.2, J(HCPA) -6.
However, when the above-mentioned reactants are mixed,
not in ti-pentane, but in tetrahydrofuran at 0 C, or when
the product (2) is treated in that solvent with an excess
of the ylide, a colorless precipitate of tetramethylphosphonium chloride is formed together with a yellow product
(3) that is soluble in ether, benzene or toluene and is
volatilc in a vacuum (sublimes at 45 Ci0.I torr. dec. 87 C;
yield 23%); at the same time a second molecule of trimethylphosphane is liberated [eq. (Ib)].
[ I ] In contrast t o hydroformylation with cobalt catalysts, olefin isomerization duc to rhodium catalysis I S completely suppresscd by complexing
agents such as phosphanes [2. 33.
[2] B. F r l l . M! Riipi1fii.s. and F . A.siiiyer. Tetrahedron Lett. 1'368, 3261.
[3] J . H . Croddock. A . Hcrslrmuri, F . E. Prriilib, and J . F. Roih, Ind.
Eng. Chem Prod. Rcs. Develop. X , 291 (1969).
[4] K. B o i f . DOS 2306405 (1973), Chemischc Werke Huls.
Tetrakis(dimethy1phosphoniumbismethylide)dinickel, a New Type of Cage Compound
By Hans Heinz Karsch and Hubert Schmidbaur"'
It was shown recently that metal-carbon o-bonds of ylide
complcxcs itre appreciably more stable than those of simple
alkyl derivatives. The effect of introducing of an "onium
center" on otherwise unstable M-C structural units is
exemplified by the unusual properties of the copper compound ( I ) and its homologsf'.21.
We now report the synthesis of an analogous nickel compound that has a binuclear structure with no less than
four Ni-C 0-bonds attached to each of the two d8-nickel
atoms.
Reaction of dichlorobis(trimethy1phosphane)nickel with
trimethylmethyleneph~sphorane[~~
in n-pentane at room
temperature affords a golden-yellow product (dec. 125 C;
yield 93 YO),
whose composition is almost independent of
the molar ratio of the reactants and which is insoluble
in that solvent or in diethyl ether but soluble in methylene
chloride. From the analytical data and particularly from
'H- and 3'P-NMR findings it is concluded that it has
the salt-like onium structure ( 2 ) , formed as shown in
eq. ( I a).
3'P-NMR (CH,Cl,, 85% H,PO,,H-decoupled, -40"C)f41:
6PA +19.9ppm, d, J(P,NiCP,) 15.2Hz; 6P, -23.6, dd,
J(P,CNiP,) 3.4; 6Pc -24.5, d, J(PANiCPc)0.
[*] Prof. Dr. H Schmidbaur and Dipl.-Chcin H. H. Karsch
lnstitut liir Anorganische Chemte der Universitiit
X7 Wiirzburg, Am Hubland (Germany)
The complex ( 3 ) formed by two-fold metalation of the
ylide is shown by cryoscopic determination of its molecular
weight to be a dimerc5]. The molecular ion of the dimer
appeared in the mass spectrum only at low ionization
energies and high target temperature ( I 8 eV, 85 C), but
then had the expected isotope distribution. Spectra measured at 70eV and 30 C, however, show only the ions
of the monomer f4)f61.
The 'H-NMR spc'c'tra of toluene solutions show only two
I : 1 doublets u i t h ;I 3 . 2 ratio of areas in the temperature
range +80 to -80°C: rCH,P 8.77 ppm, J(H,CP)
- 11.9Hz; rCH,P 11.9, J(H,CP) -4.8. P-Decoupling leads
to singlets. Double-resonance experiments prove that
J(H2CP) and J(H3CP) have the same sign. In the Hdecoupled "P-NMR spectrum 6P. at 1.7 ppm. appears
in the region for tetracoordinated onium centers['! The
IR and Raman absorptions correspond largely to those
of ( I ) and its homologs: strong bands at 665, 638 and
467cm-' can be assigned to vibrations of the skeleton
of heavy atoms.
Taking our results as a whole we propose for (3) a structure
in which two parallel square-planar Ni(CH2)" units''] are
bonded together by four dimethylphosphonium groups.
Models indicate that such a type of bonding can be strainfree. In this structure the eight-membered ring unit of
( 1 ) is present twice, as in the string by which a parcel
is tied up. It is conceivable that the monomer ( 4 ) is
in equilibrium with (3) under the conditions of the mass
853
spectroscopy. We arc describing other ylide complexes
of nickel elsewhere['].
Reccived. July 16. 1973 [Z 393 11-1
German vcrsion: Angew. Chem X i . 910 (197.7)
[ I ] H . SOiniidhuirr, J . A d k f e r , and W Birchwr, Angew. Chem. Xi. 44X
(1973); Angew. Chem. internat. Edit. 12, 415 (1973).
[2] H . Sdiiiiidbuiir and R. F r u n k . Angew Chem. 85, 449 (1973): Angew
Chcm. iiitcrniit I dit. /?. 416 (1973).
[3] H . Schmidhaur and W Tronich, Chem. Ber. 101, 595 (1968).
[4] The assignment of 1% and I'c rests on analogy with findings for
othcr square-planar alkylnickel compounds [9]. The decision is not
concluv\ c.
C',<,H4,,P4Ni2.
rel. molecular mass. calc. 473.8: found 473 (cryoscopic
in benrene). 472 (mass spectrum. snNi,).
[j]
[6] We thank N . f r t for these measurements. and Dr. W
and C. P . K i w i s for the NMR spectra.
Bw/iri(,r
171 H Schniidbuirr., W Biiditwr. and D . Sdirirrzolt.. Chem. Ber. / 0 6 , 1251
(1973)
[XI ('1 and (31 iirc diamagnetic.
[9] H . - H . Karsch, H . F . Klein, and H . Srhniidbaur, Chem. Ber., in press.
-We thank Dr. H . F KIein for valuable discussions.
Synthesis of Tris(dimethylphosphoniumbismethy1ide)chromium(rII)
By Erhard Kurras, Uwe Rosenthal, Herbert Mennenga, and
Giinther Oehme"]
Schmidbaur et a / . recently described organic ylide complexes of copper, silver"] and gold121. We have foundl-"
that reaction of methylenetriphenylphosphorane with triphenyltris(tetrahydrofuran)chromium['] or of a methyltriphenylphosphonium halide with lithium hexaphenylchrom a t e ( ~ i r )leads
[ ~ ~ to the chelate complex ( 1 ) by ortlio-metalation of a phenyl group of the ylide.
Compound (2) crystallizes in red needles that are extremely
sensitive to oxidation and hydrolysis, melt in the region
5 9 4 8 " C , dissolve very readily in solvents that d o not
contain active protons (e.g. n-hexane, benzene, toluene
or ether), and can be sublimed in a vacuum
torr,
30°C). The compound is paramagnetic (I,= 16.42.10-6
cm3 g- ', 293 cK)'81.The effective magnetic moment peffis
3.6 pB, corresponding to Cr"' with the d 3 configuration.
The characteristic fragmcnts, rn/e=(M - L) 230 (35.6 %),
(M-2L) 141 (100)and Cr 52 (34.2) can be seen alongside
the molecular ion, 319 (38.3) in the mass spectrum (70 eV;
input temperature 20, ion source 270 C ; L K B 9000).
In the IR spectrum (Beckman IR 12; 0.1 M in n-hexane;
d z 0 . 1 mm) the following bands (in cm-I) are found in
the regions free from solvent absorptions: 39O(w),43 1.5(s).
551.5(m), 660(m), 737(m), 760.5(s), 813.5(m), 933.5(vs),
970(m,sh), 1278.5(m),1288(m),1339(m), 1410(w),1418(w,sh),
1425(w).The bands at 970 and 933.5 cm- ' are to be ascribed
to the antisymmetrical and symmetrical P-C stretching
vibrations; as expected, the frequencies are shifted to longer
wavelengths compared with those of the free ylide ( v ~ , ~ :
1006cm-'~"]).In the lower frequency region the bands
at 431.5 and 390 or. more probably, those at 552.5 and
431.5 ern- correspond to the antisymmetrical and symmetrical Cr-C stretching vibrations.
Compound (2) gives typical reactions of organometallic
compounds. In ethereal solution it reacts with, for instance,
carbon dioxide and benzophenone. The phosphonium salt
formed by protolysis according to the equation
(21
+ 6HCI
THF
CrC1.dTHF)3 + 3[(CH,),P]CI
was isolated and characterized as chloride and tetraphenylborate.
These findings indicate an octahedral arrangement of the
C-Cr-C
units. It is less likely that there is electron
(-)
However, interaction of lithium hexaphenylchromate(r1i)
and tetramethylphosphonium chloride in tetrahydrofuran
under anaerobic conditions affords analogously tris(dimethylphosphonium bismethylylide)chromium(rrr) (2).
The latter product can also be prepared by treating
CrCI.$(THF)3[h1
with methylenetrimethylphosphorane that
has been metaiated by methyl- or phenyl-lithium['] :
[*] Dr. habil E. Kurras, Dip].-Chem. U. Rosenthal,
Dr. H. Mennenga. and Dr G Ochme
Zentrahnstitut fur Organische Chemie
der Akademie der Wissenschaften der DDR
Bercich Kom plcx h a t a l > w
DDR-25 Rostock. Buchbinderstrasse 5-6
854
delocalization in the >C=PMe2--C<
group as in the
ally1
by analogy with tris(allyl)chromium" ' I ,
together with involvement of the phosphorus. The charge
distribution shown schematically in ( 3 ) clearly stabilizes
the polar Cr-C o-bond, and Cr-P interaction is not
be excluded.
An X-ray structure analysis of ( 2 ) is in progress
Received. J u l y 27, 1973 [Z X94 IF]
German bcrsion: Angew Chem. X i . 913 (1973)
[ I ] H. S~hriiidhurir.J . 4d/L&r, and W Buchnu. Angrw. Chem. 8.5, 44X
(1973): Angew. Chem. internat. Edit. 12, 415 11973).
[2] H . Schniidhuirr and R. Frorikr. Angrw. Chcm. 8.5.449 (1973). Angew.
('hcm internat. Fdit. /?. 416 (1973).
[3] t. Kirrrus and J . M e w t i e r , Proc. XV. Conf. Coord. Chem. Moscow
1973, L11-114: J . Meissnrr, D~ssertation,Universitit Rostock 1972.
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dinickel, compounds, cage, typed, tetrakis, new, dimethylphosphoniumbismethylide
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