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New Dihydrido-Bridged Binuclear Platinum-Iridium Complexes.

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[2] F B. Darns. E. L. Grffin, I Am. Chem. SOC.35, 959 (1913).
[3] H -J. Wolheber. Dissertation. University of Marburg 1980.
141 N M . Lin, C. Wentrup, Helv. Chim. Acta 59. 2068 (1976).
151 J. Becker, C. Wenrrup, E. Kafr, K:P. Zeller, J . Am. Chem. SOC.102, 5110
(1980). R. F C. Brown, F W. Eastwood. G. P. Jackman, Aust. J. Chem. 30,
1757 (1977).
161 H.- W. Winter, L. A. J. Kohler, C. Wenrrp, unpublished.
171 Manufacturer: Air Products. Allentown, Pa. The distance between the exit of
the pyrolysis tube and the KBr target was ca. t cm.
181 Experiments in collaboration with H. Briehl.
[9] H Sraudinger. E Hauser, Helv. Chim. Acta 4. 887 (1921). For spectral data,
see also J . K. Crandall, W. W. Conover, J. Org. Chem. 39, 63 (1974).
Support for the presence of the terminal and bridging hydride ligands in (1) and (2) is provided by 'H-NMR spectroscopy. The 'H and "P-NMR spectra of ( l a ) in CD2C12,dissolved and measured at - 6 0 ° C are assigned as follows:
S = -7.05 (H2, 'J(PtH)=671 Hz), -9.04 (H3, 'J(PtH)=662
Hz), -15.27
(H4); 16.3 (Pl, 'J(PtP1)=3656 Hz,
New Dihydrido-Bridged Binuclear Platinum-Iridium
By Attilio Immirzi, Alfred0 Musco, Paul S. Pregosin, and
Luigi M. Venanzi"'
Carbonyl complexes having bridging hydrogen atoms are
rather common in transition metal chemistry[''. Recently,
bridging hydrido complexes not containing CO ligands have
received considerable attentionf2].Whereas a number of hydrido-bridged bi-homometallic complexes have been reported['],only few examples of heterometallic complexes are
k n ~ w n ' ~We
, ~ report
here the synthesis and structural characterization of the stable mixed Pt-Ir cations (1) and (2)
containing double hydrido bridges.
The cations (1) and (2) are formed as follows:
+ [IrHS(PEf3)2] (1) or (2) + HZ
As shown in the above equation the reaction occurs with
transfer of a phosphane ligand from platinum to iridium, a
rather uncommon phenomenon in the absence of free ligand[51 The rather novel nature of the above complexes
prompted us to undertake the X-ray structure determination
of ( l a ) IBPb] (Fig. 1)@].The molecular geometry of the
cation ( l a ) is consistent with a square planar Pt" and an octahedral Ir"' with two bridging H atoms between them and
one terminal H atom on Ir. The atoms Pt, P1, C1, Ir and P2
are nearly coplanar with PI and P2 in a cisoid arrangement.
The axial ligands Et3P3 and Et3P4 are slightly bent towards
the bridging hydrogens thus reducing the steric interaction
with the equatorial phosphane ligand Et3P3. The Pt . . .Ir distance is practically identical with the Pt ...Pt distance
(2.69213) A) in [(Cy3P)(Me3Si)Pt(p-H),PT(Me3Si)(Cy,P)]
(Cy = cyc10he:yl)l~~ and slightly longer than the Ir ... Ir distance (2.518 A) in [(Ph3P)2(H)Ir(p-H)31r(H)(Ph,P)2][PF6][81,
as expected for a compound with three bridging hydrogens.
['I Prof. L. M. Venanzi, Dr. A. Musco, and Dr. P. S. Pregosin
Labordtorium fur Anorganische Chemie, ETH-Zentrum
CH-8092 Zurich (Switzerland)
Dr. A. lmmirzi
lnstituto di Chimica delle Macromolecole del C.N.R.
Via A. Corti 12. Milano (Italy)
I"] This work was supported by the Swiss National Science Foundation. The
Authors wish to thank the C.N.R. (Rome) for a leave of absence to A. M.
Angew. Chem inr. Ed Engl 19 (1980) No. 9
Fig. I. Molecular structure of the cation (fa). Bond lengths [A]:
Pt-C 2.08(2). Pt-PI 2.21 3(6), lr-P2 2.323(5), Ir-P3 2.354(6), Ir-P4
bond angles ["I PI-Ir-P2
138.2(1). Pt-Ir-P3
86.6, Pt-Ir-P4
133.0(3), Ir-Pt-PI
140.7(1), P2-1r-P3
96.6. P2--Ir-P4
1 '): PI-Pt--lr-P2
165.7(1); torsion angles (", avg. error
- 100: P2-Ir--Pt-C1
94, PI-Pt--Ir-P4
- 82, P4-Ir-Pt-CI
- 178,
4J(PlP2)=43 Hz, ,J(PlP3)=4 Hz), 6.0 (P2, 'J(P2P3)= 18
Hz), - 4.5 (P3, 'J(PtP3) =40 Hz). On warming to - 30 "C a
new set of signals appear and these are assigned to isomer
(lb): S = -4.18 (H2 or H3, 'J(PtH2 or H3)=826 Hz),
- 11.64 (H3 or H2, 'J(PtH3 or H4) = 525 Hz), - 14.61 (H4),
18.7 (PI, lJ(PtP1)=3349 Hz), ,J(PIP3)=4 Hz), 5.6 (P2,
'J(P2P3) = 18 Hz), - 2.3 (P3, 3J(PtP3) = 36 Hz). At this temperature a 1 : 1 mixture of ( l a ) and ( l b ) is obtained in ca. one
hour. The same isomeric composition is observed at room
temperature. Of special interest in isomer ( l a ) is that: (a) the
appearance of H3 immediately allows its assignment since
this hydrogen is trans to two PEt3 groups and therefore,
shows two large 'J(PlH3) and 'J(P2H3) values (66 Hz)['] and
(b) H2 does not show large (>20 Hz) 'J(PlH2 or P2H2) couplings. In isomer (lb), however, both H2 and H3 show one
strong 'J(PH) coupling (ca. 74 Hz).
Similar spectral observations and structural assignments
have been made for (2a) and (2b).
( l a ) fBPh$: A solution of AgBF, (0.143 g, 0.73 mmol) in 3
ml of methanol was added to a suspension of trans[PtC1(C6H5)(PEt3)2]
(0.400 g, 0.73 mmol) in 5 ml of methanol
and the AgCl filtered off. [IrH5(PEt3),](0.319 g, 0.73 mmol)
in 5 ml of methanol was added to the colorless filtrate. The
resulting yellow solution was treated with a solution of
NaBPL (0.252 g, 0.73 mmol) in 5 ml of methanol. A yellow
microcrystalline solid ( l a ) [BPh,] precipitated and was collected by filtration (0.663 g, 72% yield). ( l a ) may be recrystallized from CH2C12/CH30H.(2a) [BPh,] was prepared in a
similar fashion starting from trans-[PtC1(H)(PEt3),1.
0 Verlag Chemie, GmbH, 6940 Wernheim, 1980
Received March 26. 1980 [Z 552 IE]
German version Angew. Chem. 92. 744 (1980)
S 02 50/0
[l] R. Bau, R. G. Teller, S. W Kirtley, T. F Koetzle, Acc. Chem. Res. 12, 176
[ 2 ] G. Bracher, D. M . Grove, P. S. Pregosin, L. M . Venunzi, Angew. Chem. 91.
169 (1979); Angew. Chem. Int. Ed. Engl. 18, 155 (1979) and references cited
[3] N . W. Alcock. 0. W. Howurth, P. Moore, G. E. Morris. J. Chem. SOC.Chem.
Commun. 1979, 1160.
141 J. P. C M. Von Dongen, C. Musters, J. P. Visser. J. Organomet. Chem. 94, C
( J a ) kt
29 (1975).
[S] R. Huis. C. Masters, J. Chem. SOC.Dalton Trans. IY76, 1796.
[6] ( l a ) [BPb] is monoclinic, space group P2,/a; a=20.578(3). b = 15.046(3),
c = 18.222(3)
13=94.52(2)", Z=4. 6852 reflections (d>0.95
were measured by an automatic counter diffractometer (Philips PW-1100) using CuK,.
radiation. The 5603 reflections having I,,, > 3 u were used in the structure determination. Atomic positions were obtained by the Patterson-Fourier method and refined using the least squares procedure with unitary weight factors,
isotropic thermal vibration and 4 x 4 block diagonal approximation down to
[7] M. Ciriano, M . Green, J. A . K. Howard, J. Proud, J. L. Spencer, F. C A .
Stone, J . Chem. Sac. Dalton Trans. 1978, 801.
[S] R. H. Crabtree, H. Felkin, G. E. Morris, T. J. King, J. A. Richards, J. Organomet Chem. 113. C 7 (1976).
191 J. P. Jesson in E. L. Muetterriesi Transition Metal Hydrides Marcel Dekker,
New York 1971.
The =PCN Group as a Pseudochalcogen;
By ASfred Schmidpeter, WoSfgang Gebler, Franz Zwaschka,
and William S. Sheldrick"1
Dedicated to Professor Karl Dimroth on the occasion of
his 70th birthday
The "cyano displacement principle"['"] suggests the
-P(CN), group to have the character of a pseudohalogen,
and the -=PCN group to have the character of a pseudochalcogen. The pseudohalogen character has been shown in the
ions P(CN);, P(CN)2Br;, and P(CN),II['~;we sought to establish the pseudochalcogen character by means of cyanophosphinidene analogues (3) of the 0x0- or thioxo derivatives of nitrogen heterocycles. The synthesis of these new
compounds can be accomplished via the dicyanophosphide
ion by reductive removal of CN developed for the production of P(CN);['"]. In the case of (3a) this reaction starts initially from benzimidazolone, so that (3a) really is formed by
O/PCN exchange, not just formally.
The tetrafluoroborates (I)[" obtained by methylation of
the 2-chloroheterocycles with HC(OMe),BF, react with
[18]crown-6-sodium dicyanophosphide or triethylammonium dicyanophosphide['' to give the respective 2-(dicyanophosphino) chlorides (2) (Table 1). Treatment with sodium
diethylphosphite generates the cyanophosphinidene-heterocycles (3j.
The cyanophosphinidene-heterocycles(3) (Table 1) occupy a connecting position between the phosphamethinecyanine cations synthesized by Dimroth as the first (-P-=C-)
compound^[^^ and the dicyanophosphide anion''"]. In a metathetic reaction these ions afford the salts (4) (Table l ) which
have the same composition as compounds (3). They are sta-
[*] Prof Dr. A. Schmidpeter, DipLChem. F. Zwaschka, W Gebler
Institut fur Anorganische Chemie der Universitat
Meiserstrasse 1, D-SMX, Miinchen 2 (Germany)
Prw-Doz. Dr. W S. Sheldrick
Gesellschaft fur Biotechnologische Forschung mbH
Mascheroder Weg 1, D-3300 Braunschweig-Stockhelm (Germany)
R = CH3
ble as crystals, but surprisingly rearrange in solution even at
room temperature, e. g. on attempted recrystallization, affording (3). The exchange could proceed via a diphosphetane
betaine (5)l41.
Table 1. Compounds of types (2), (3). and (4).
brick red
162 (dec)
- 38
- 193
- 193
3.77 [c]
[a] In CH,CN, (30,bj in tetrahydrofuran. [b] Methyl protons. [c] 4JpH
= 2.5 Hz.
The cyanophosphinidene-heterocycles (3) form air-stable
acicular crystals. The "P chemical shifts lie roughly in the
middle between those of P(CN); and those of the corresponding phosphamethine cyanine cation, i. e. between the
two 8(31P)values of (4). Their CN stretching vibration is
shifted by about 75 cm-' to longer wavelengths relative to
that of cyanophosphines but is close to that of P(CN);[l'l and
Cyanophosphorus Compounds, Part 6 This work was supported by the
Deutsche Forschungsgemeinschaft and the Fonds der Chemischen 1ndustrie.Part 5: W S. Sheldrick, A . Schmidperer, F Zwaschka, K . B Dillon, A . W G.
Plorr, T. C. Waddington, J. Chem. Sac. Dalton Trans., in press.
0 Verlag Chemie, GmbH, 6940 Weinheim, 1980
Angew. Chem. Int. Ed. Engl. 19 (1980) No. 9
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binucleata, platinum, dihydride, bridge, iridium, complexes, new
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