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Carbodiimides as Source of Isocyanide and Carbonyl Ligands.

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phosphin0)methane to give the ylide/phosphinomethanide
complex ( 3 ) .
The yellow crystalline diamagnetic product shows mass
and IR spectra which reveal quite clearly the close relation
to the precursor (2) on the one hand and to ylide complexes
on the other.
‘H- and ‘H{31P)-NMR spectra, but above all the 31P{1H}NMR spectrum, support the proposed structure (3); the latter
shows a structurally diagnostic doublet/triplet pattern (2 : I),
which confirms the symmetrical bonding of the ligands.
In an analogous way reaction of(Me3P)AuC1and ( 1 ) affords
the lemon-yellow insoluble gold(1) bis(diphenylphosphin0)methanide ( 4 ) , which is characterized by its 19’Au Mossbauer
spectrum as a polymeric Au’ derivative with the metal atoms
in a uniform environment (IS=4.09, QS =9.25 mm/s; 4 K)C51.
( 4 ) reacts with the ylide to form the eight-membered heterocycle ( 5 ) , in which, unlike in ( 3 ) , neither the ylide nor the
diphosphinomethanide assume a chelating function, serving
instead as bridges between the metal atoms.
2 (Me3P)AuCl
+
2 (1)
2 Au[CH(PPh2)2]
Received: July 5, 1977 [Z 779b IE]
German version: Angew. Chem. 89,679 (1977)
CAS Registry numbers:
( I ) , 28926-61-6; (Z), 63528-02-9; (3), 63528-03-0; ( 4 ) , 63528-04-1; ( 5 ) ,
63528-05-2; (Me3P)2PdCIZ, 25892-38-0; (Me,P)AuCI,
15278-97-4;
MeEt2PCH2,44514-33-2
[l] H . Schmidbaur, Acc. Chem. Res. 8, 62 (1975); E. Kurras, U . Rosenrhal,
H . Mennenga, G . Oehme, Angew. Chem. 85, 913 (1973); Angew. Chem.
Int. Ed. Engl. 12, 854 (1973); H . Schumann, S. Hohmann, Chem. Ztg.
100, 365 (1976); L. E. Manzer, Inorg. Chem. I S , 2567 (1976).-For
analogous sulfur compounds see H . Schmidbaur, W Richter, 2. Anorg.
Allg. Chem. 429,222 (1977);P.Braoo, G. Fronza, C . Ticozzi, J. Organomet.
Chem. 118, C78 (1976).
[2] K. issleib, H . P . Abicht, J. Prakt. Chem. 312, 456 (1970); K . Isslerb,
H . P . Abicht, H . Winkelmann, Z. Anorg. Allg. Chem. 388, 89 (1972).
[3] A . Camus, N. Marsich, G . Nardin, L. Randaccio, J. Organomet. Chem.
60, C39 (1973).
[4] H . Schmidbaur, W Tronich, Cbem. Ber. 101, 595 (1968).
[5] We thank Doz. Dr. F . E. Wfyjiw. Physik-Department der TU Miinchen,
for measuring the spectrum.
[6] Elemental analysis gave correct values for (2)-(5).
(4)
Carbodiimides as Source of Isocyanide and Carbonyl
Ligands “*I
Ph9
HI
The colorless, crystalline compound ( 5 ) , which is soluble
in benzene, was identified, like ( 3 ) , by mass, IR, and NMR
spectrat6!
Procedure:
(1)+(2)-+(3): To a suspension of (Me3P)2PdC12(330 mg,
1 mmol) in THF (10ml) is added a solution of (I) (2mmol)
in THF (20ml). After 3 h the orange-yellow precipitate is
filtered off, washed with THF and pentane, and dried at
60”C/0.1 torr: Yield 830mg (98 %) (2), dec. pt. 190°C.-A
suspensionof ( 2 ) (2.18g,2.5mmol)in benzene(l0ml)is treated
with MeEtzPCHz(2.5 mmol) and stirred for 30 minutes. After
removal of solvent the residue is taken up in toluene; (3)
is then precipitated by addition of pentane. Yield 740mg
(50%), m.p. 150°C; MS: m/e=608 [M+(lo6Pd)].
‘H-NMR ([D8]-toluene, TMS int.): 6CzHS 0.83 and 0.47,
A3B2X, 10H; 6PdCHz -0.35, m, 4H; 6CH 2.9, “t”, I H ,
JHCp3 Hz; 6C6H5 5.85, m, 20H.-”P-NMR
([D8]-toluene,
H3P04 ext.): GPPd 21.2, d, 2P; 6PEt2 -25.3, t, IP, JpCpdp
8.
(1)+(4)+(5):
To a suspension of (Me3P)AuCl (308 mg,
1 mmol) in 10ml THF is added a solution of the equivalent
amount of (1) in THF. The yellow precipitate is washed
with THF and pentane and then dried at 6O0C/O.1 torr. Yield
490mg (85%) ( 4 ) , dec. pt. 240°C.-A suspension of ( 4 )
(480mg, 0.82mmol) in benzene (10ml) is treated with 50mg
(0.43mmol) MeEtZPCH2. After decoloration the solution is
filtered and the filtrate evaporated down. (5) is precipitated
by addition of pentane. Yield 275 mg (75 %), m.p. 186°C (from
toluene/pentane); MS: m/e=894 [M’]; IR: v(AuC)= 550,
v(AuP)= 388 cm - I .
‘H-NMR (C6D.5, TMS ext.): 6CH3 0.87, dt, 6H, J H C ~
7Hz, J H C C ~18; 6CCHz 1.25, m, masked by 6AuCH2 1.10,
d, JHCp 9 (together 8 H); 6CH 2.50, “t”, 1H, JHCP 4.5; 6C6HS
7.70, m, 20H.-”P-NMR
([Ds]-toluene, H3P04 ext.): GPAu
-23.2, d, 2P; GPEt, -27.8, t, IP, J p c ~ ” p12.
Angew. Chem. I n t . Ed. Engl. 16 ( 1 9 7 7 ) N o .
9
By WolfPeter Fehlhammer, Andreas Mayr, and Michael Ritter[*l
Application of the Ugi reaction[’’ to carbamoylmetal compounds (C-metalated formamides) leads to isocyanide complexes under extremely mild conditions[’. Deprotonated
carbamoyl complex species[3a1,
as formed by simple addition of
isocyanates to carb~nylmetalates[~~~,
may also be used as
starting material. This synthetic principle, which is apparently
of general validity for heteroallenes X=C=NRI41, is demonstrated for carbodiimides. In the presence of electron-rich
metal compounds this heteroallene also proves to be a
productive source of novel carbene complexes.
The reaction between carbonylmetal anion and carbodiimide, which requires from a few minutes at -78°C [(I),
(la)] to several weeks at room temperature [(I), (2b)], can
be followed by IR spectroscopy. The disappearance of the
v,,(NCN) band of the free carbodiimide is accompanied by
the appearance of new bands in the region of 1500-1 600 cm which we assign to v(N=C=N) vibrations of an adduct of
the C-metalated formamidine type ( 3 ) . At the same time
the v(C0) bands shift to higher wavenumbers, indicating delocalization of the negative charge over the entering allene system.
(“-I)-
,TJR
(3)
LmM-C;?
NR
Protonation of this adduct with HCl in tetrahydrofuran
leads to the diaminocarbene complexes ( 4 ) and ( 5 ) , thus
supporting formulation (3).
[*] Dr. W. P. Fehlhammer, Dip1.-Chem. A. Mayr, M. Ritter
Institut f i r Anorganische Chemie der Universitat Erlangen-Niirnberg
Egerlandstrasse I , D-8520 Erlangen (Germany)
[**I Isonitrile Syntheses at the Metal, Part 3. This work was supported by
the Deutsche F0rschungsgemeinschaft.-Part 2: [2].
641
(OC), C r C (NHR)
[rl5-C5H5Fe (CO)2 { C (NHR)2 ) ] C 1
(4)
(5)
As expected, on reaction with phosgene ( l a ) is split
into the isocyanide complex (6) and NC6H:-, which occurs
as phenyl isocyanate.
coa,
- 2 NaCI, - CsHsNCO *
(la)
(OC),CrC%NCBH5
(6)
This reaction clearly demonstrates the analogy between
(3) and N,N-disubstituted urea, which react with phosgene
to give two molecules of isocyanate15]. Surprising, and inconsistent with the intermediacy of ( 3 ) , however, is the formation
of the diisocyanide complex (7 j.
(2)
em2
- NaCI, - C%
[qS-C,H5Fe(CO)(C=NR)2J
C1
Received: June 27, 1977 [Z 775 IE]
German version: Angew. Chem. 89. 660 (1977)
(7)
For this reason we assume (2), which can be isolated as
yellow sodium salt, to have the chelate structure ( 8 ) , resulting
from a primary product (3) by intramolecular nucleophilic
attack of a carbodiimide nitrogen at the neighboring carbonyl
ligand. In agreement with the suggested structure ( 8 ) the
IR solution spectrum of (2) shows only one v(C0) band
(1886cm-') accompanied by a remarkably intense structured
band at ca. 1550 cm-' [v(N-C-N)+v(C=O,
carboxamide)] .
L
of N ~ [ T ~ ~ - C ~ H ~ F(20
~ (mmol)
C O )in
~ ca.
] 200 ml THF19].The
mixture is allowed to warm to room temperature, stirred
for a further 15 minutes, and then re-cooled to - 78 "C.
[r15-C5H5Fe(C0)2(C(NHC~H~)~~]PF6
(I Oa): 50mmol
HCI in ether is added dropwise with stirring to a solution
of (2a). The mixture is evaporated to dryness, dissolved
in water, and treated with NH4PF6 solution. Recrystallization of the resulting precipitate affords 5.5 g (53 % based
on [CpFe(CO)2]2) ocher-colored crystals, m.p. 125"C.
[q5-C5H5Fe(CO)(CNC6H5)2]PF6(I1 a ) : A 1 M solution
of phosgene in THF (20ml) is added dropwise with stirring
to a solution of ( 2 a ) and the product isolated as in the
case of (IOU). Recrystallizationfrom ethanol yields 6.1 g (63 %)
light-brown crystals, m.p. 142 "C.
J
A similar FeC(NHR)N(R)C(NHR)four-membered ringproduct of addition of methylamine via two cis RNC ligands
in hexakis(methy1 isocyanide)iron(II)-has been confirmed Xray crystallographically[6].Most likely the isomerization carbamoyl(isocyanide)+carbonyl(carbene)
observed
on addition of amine to Mn(C0)4(CNR): also proceeds via
a four-membered ring as intermediate.
The reaction behavior of the iron adducts follows from
their carboxamide structure ( 8 ) . Thus, protonation leads to
cleavage of the four-membered ring at the CN carboxamide
whereas phosgene attacks the exocyclic CO bond['],
causing ring opening in the formamidine moiety. In that case
the carbodiimide molecule is completely used up for the construction of two isocyanide ligands, and the C atom required
for mass balance is provided by a CO ligand.
Previously, complexes of type (7) were obtained only
by substitution reactions, which naturally afford mixed products. The reaction of carbodiimides with carbonylmetalates
and acids allows their direct synthesis and at the same time
opens up a convenient entry to complexes such as ( 4 ) and
( 5 ) , which hitherto could not be synthesized by alternative
routes.
Carbodiimides behave "quasi-ambivalent" toward metals:
only the most electron-rich metal compounds obviously are
capable of interacting with the weakly electrophilic carbodiimide carbon. In contrast, coordination to metals in higher
oxidation states proceeds via one or even both nitrogen atoms,
as observed, e.g., in insertion products of type (9)18'.
CAS Registry numbers:
(I a), 63428-75-1; ( 1 b), 63428-74-0; ( Z a ) , 63428-73-9; ( Z b ) , 63428-73-8;
( 4 a ) , 63466-39-7; ( 4 b ) , 63428-71-7; ( 5 a ) , 63428-70-6; ( 5 b ) , 63428-69-3;
(6), 14782-94-6; (7a), 63428-68-2; (7b), 63428-67-1; (8a), 63428-66-0; ( 8 b ) ,
63428-65-9; (1Oa), 63428-64-8; (1 I a ) , 55451-30-4; Na[C5H5Fe(C0)2],
12152-20-4
[l] Cf. I. Ugi, U . Fetzer, U. Eholrer, H . Knupfer, K . Oflermunn, Angew.
Chem. 77,492 (1965); Angew. Chem. Int. Ed. Engl. 4,472 (1965).
[2] W P. Fehlhammer, A . M a y r , Angew. Chem. 87, 776 (1975); Angew.
Chem. Int. Ed. Engl. 14, 757 (1975).
[3] a) W P. Fehlhammer, A . M a y , unpublished; b) R . J . Angelici, Acc.
Chem. Res. 5, 335 (1972).
[4] The splitting off of S2- from isothiocyanate adducts of carbonylmetalate
ions proceeds particularly smoothly: W P. Fehlhammer, A. M a y , unpub-
lished.
[S] H. Ulrich, A. A . R . Sayigh, Angew. Chem. 78, 761 (1966); Angew. Chem.
Int. Ed. Engl. 5 , 704 (1966).
[6] J . Miller, A. L. Bolch, J . H. Enemark, J. Am. Chem. SOC.93, 4613
(1971).
[7] 7: Sawai, R. J . Angelici, J. Organomet. Chem. 80, 91 (1974).
[8] S . D. Robinson, A . Sahajpal, J. Organomet. Chem. If 7, C 11 1 (1976).Insertion of dimethylcarbodiimide into the metal-hydrogen bond of
H2Fe(C0)4, however, leads to the bis(methy1amino)carbene complex:
K . dfele, private communication; cf. also K .
C . G. Kreiter, Chem.
Ber. 105. 529 (1972).
[9] J. E. Ellis, E. A . Flom, J. Organomet. Chem. 99, 263 (1975).
of&,
Repetitive Peptide Synthesis with Insoluble PolymerBound Reagents and Solubilizing Macromolecular P e p
tide CarriersC**l
By Gerhard Heusel, Giinter Bovermann, Walter Gohring, and
Giinther Jung
For chain lengthening, peptides bound C-terminally to soluble polymeric carriers react quantitatively with activated Nprotected amino acid esters which are bound to an insoluble
matrix.Weused the crystallizable polyoxymethyleneintroduced
by Buyer and Mutter['] for peptide synthesis as solubilizing
peptide carrier and the N,-tert-butyloxycarbonylamino acid
ester of 2-nitrophen01[~]and l-hydroxyben~otriazole~~~
bound
to crosslinked polystyrene as insoluble polymeric reagent (see
Fig. 1).
[*] Prof. Dr. G. Jung, DipLChem. G. Bovermann, Dr. W. Gohring, Dip].-
Procedure
Adduct ( 2 a ) : A solution of diphenylcarbodiimide (20mmol)
in THF (50ml) is added with stirring at -78°C to a solution
642
Chem. G. Heusel
Institut fur Organische Chemie der Universitat
Auf der Morgenstelle, D-7400 Tubingen (Germany)
[**I This work was supported by the Deutsche Forschungsgemeinschaft.
Angew. Chem. Int. Ed. Engl. 16 (1977) N o . 9
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