5175 CsH4CH~substitutedpolymer suspended in a solution of Fe(C0)S in toluene. A. Davison, J. A. McCleverty, and 0.Wilkinson, J. Chem. Soc., 1133
(1963). R. K. Kochhar and R. Petit, J. Organomet. Chem., 6, 272 (1966). M. L. H. Green, C. N. Street, and G. Wilkinson, Z.Nsturforsch.,TeiIB, 14,
738 (1959).
been reported by Halpern and coworker^,^ a similar pattern for 1 should be expected to have absorption bands at higher wavenumbers." In fact the anion [COII'(CN)~]-~ has an absorption band at 2154 whereas a band at 2183 cm-' has been assigned to a p-CN group
M. L. H. Green, and P. L. I. Nagy, J. Chem. Soc., 189 (1963). K. P. C. Volihardt, J. E. Bercaw, and R. G. Beraman. J. Oraanomet. Chem.,
97,283 (1975). W. S.Lee and H. H. Brintzinger, J. Organomet. Chem., 127, 87 (1977). W. S.Lee, J. D. Kooia, and H. H. Brintzinger, unpublished work. On leave from Donegani Institute, Novara, Italy.
Giuseppe Gubitosa,13Manfred Boldt, Hans H. Brintzinger* Fachbereich Chemie, Universitat Konstanz 0-7750 Konstanz (B.R.D.),West Germany Received January 26. 1977 Reaction of Cyanocobaltate(I1) and Cyanomolybdate(V) Ions with Molecular Oxygen. A Bimetallic Dioxygen Adduct Sir: The ability of cobalt(I1) complex ions to bind molecular oxygen to form peroxide and superoxide compounds is well These adducts are characterized by a wide variety of structure and r e a ~ t i v i t y . ~ ~ course of a study In- the on bimetallic catalysis in autoxidation reactionsI0 we became involved in an investigation of the interaction of metal couples in the presence of oxygen. This led to the discovery of a new type of dioxygen adduct containing two different metals. Thus CoC12 and MoCls in the presence of excess KCN react with 0 2 to give a stable adduct according to eq 1.
0,
+ COCI, + MoC15 ~ , 6K,KCN
r
C'
L
Furthermore, the brown dioxygen adduct 3, obtained with cobalt alone5 under identical experimental conditions (eq 2)
as used to obtain 1, and known to lack a cyano bridging structure has absorption bands at 2080,2100,2130, and 2160 cm-' assigned to cyano groups. Most of the experimental evidence presented above supports the formulation given for 1; a doubt, however, persisted as to whether 1 was a mixture of 3 and a molybdenum compound. Duplicating the experimental procedure in the absence of CoCl2 resulted in a sky-blue solid (4) lacking any peroxidic function and having the following infrared characteristic^^^ (KBr): 21 15, 2100 (-CN), 1400, 1315 (MOO), 915 (Mo=O?), 828-840 (MoOMo?), 380 (MoCN), 329, 295 (MoCI). Anal. Calcd for CloKgM02C12N1003: C, 13.59; K, 35.40; Mo, 21.72; C1, 8.02; N , 15.84. Found: C, 13.75; K, 35.90; Mo, 22.30; C1, 8.23; N, 15.98. These results suggest formulation 3.25
1
1 ' 1
(CN)jCo'1'0,M~~'(CN)5.3H>O
I1
4
0
The presence of Mo-C1 in 4 was a good indication that the same pattern rather than Co-C1 was present in 1. Additional (1) support for 1 being a single compound was given by the fact that a synthetic mixture of 3 and 4 did not give 1 upon rePassing a stream of 0 2 through a cold aqueous solution (60 crystallization, whereas 1 could be recrystallized without almL) of KCN (0.128 mol, 8.4 g) containing MoCls (0.008 mol, tering significantly its composition. It must be noted that l is 2.2 g) and CoC12 (0.008 mol, 1.04 g) for 1 h resulted in a dark not obtained when molybdenum(V1) species are used; furgreen solution. Addition of precooled ethanol precipitated thermore the use of deficient amount of cyanide ion also preimmediately a light green solid which was filtered, washed with vents its formation. Compound 1 constitutes, on one hand, the n-pentane, and dried under vacuum:" IR (KBr) 3500, 1650 (H20), 2155,2128,2100 (-CN), 918 (MFO), 893 (00), first example of a dioxygen adduct containing two different metals, and on the other the first peroxidic molybdenum species 840 (MOOor COO),414 (COCEN?), 396 (MoCEN), 327 directly with molecular ~ x y g e n . ~ ' We , ~ * are presently (MoC1). Anal. Calcd for C ~ O H ~ C O K ~ M O Cc, ~N 15.3; ~ O ~ ~obtained : pursuing the study of this and related compounds. H, 0.77; Co, 7.5; K, 29.8; Mo, 12.2; Q 4 . 5 ; N, 17.8; 0, 12.2. Found: C, 15.3; H, 0.75; Co, 8.2; K, 3 1.1; Mo, 1 1.8; C1,5.3; N, References and Notes 17.6. (1) A. G. Sykesand J. A. Weil, Progr. Inorg. Chem., 13, l(1971). The presence of a peroxide ligand, suggested by the infrared (2)J. Valentine, Chem. Rev., 73,235 (1973). absorption band at 893 ~ m - ' , was ~ , ~confirmed by a standard (3)G. Henrici-Olive and S. Olive, Angew. Chem., Int. Ed. Engi., 13, 29 peroxidic titration in the presence of acetic acid, indicating one (1974). (4)L. Vaska, Acc. Chem. Res., 9, 175 (1976). 0-0 moiety per molecule of 1.12 A thermal decomposition (5) A. Haim and W. K. Wilmarth, J. Am. Chem. SOC.,83,509(1961). (100 "C) of 1 causing a loss of weight corresponding to l/2 of (6)M. Mori and J. A. Weil, J. Am. Chem. SOC.,89,3732 (1967). (7)M. Mori and J. A. Weil, J. Am. Chem. SOC.,90,615 (1968). 0-0 per m ~ l e c u l e was ' ~ further evidence for a peroxide (8)R. Davies, M. B. Stevenson, and A. G. Sykes, J. Chem. SOC.A, 1261 group. (1970). The presence of an intense and sharp absorption band at 918 (9)J. Halpern, B. L. Goodall, G. P. Khare, H. S. Lim, J. J. Pluth. and J. A. Piuth, J. Am. Chem. Soc., 97,2301 (1975). cm-l indicates a Mo=O group; this is in accord with similar (10)H. Arzoumanian, A. Blanc, U.W i g , and J. Metzger, Tetrahedron Lett., 1011 bands reported in the 1 i t e r a t ~ r e .Sharp l~ absorption bands at (1974). (11) Ail attempts to grow a crystal for x-ray.anaiysis were unsuccessful, since 2155, 2128, and 2100 cm-I are assigned to cobalt and mothe only adequate cosolvent, water, decomposed 1 during the crystallization lybdenum cyano groups.16-22Although an unusual cyanide period. bridging structure for the cobalt dioxygen adduct 2 (12) Treatment of 1 with a strong acid (H2SO4) gave rise to the evolution of 0 2 1
(CN)2( PMePh)3CoNCCo(PMe2Ph)2(CN)02 2 with absorption bands at 2085 and 2105 cm-' has recently
cotrespondingto 70% of the peroxidic moiety present in 1. This low value is not unusual for this type of analy~is;'~ for example the decacyancdicobait dioxygen adduct (3)yielded, upon strong acid treatment, the amount of 02 corresponding to 50% of 0-0per molecule. (13) R. G. Charles and S. Barnartt, J. Inorg. Nucl. Chem., 22, 69 (1961). (14)This loss of weight was not due to dehydration since the IR absorption bands
Communications to the Editor
5176 at 3500 and 1650 cm-I (H20) were unchanged after the thermal treatment. J. Selbin, J. Chem. €doc., 41, 66 (1964). S. J. Llppard and B. J. Russ, Inorg. Chem., 8, 1943 (1967). P.C. H. Mitchell and R. J. P. Wllllams, J. Chem. Soc.,1912 (1960). B. M. Chadwick and A. G. Sharpe, A&. Inorg. Chem. Radiochem., 8 , 8 6 (1966). D. A. White, A. J. Soiodar, and M. M. Baizer, lnorg. Chem., 11, 2180 (1972). S. F. A. Kettle and R. V. Parish, Spectrochim. Acta, 21, 1087 (1965). J. Van de Poel and H.J. Newmann, lnorg. Chem., 7, 2086 (1968). A. Samotus, M. Dudek, and A. Kanas, J. lnorg. NucI. Chem., 37, 943 (1975). A. G. Sharpe, "The Chemistry of Cyano Complexes of the Transition Metals", Academic Press, London, 1976, p 177. Although eq 3 Includes 02 as a reactant, It was shown that 4 could also be obtained in the absence of oxygen. The oxidation state Mo(V) was established by a Ce(1V) N. H. Fwman and W. M. Murray, J. Am. Chem. Soc., 58, 1689 (1936). H. Mlmoun, I. Seree de Roch, and L. Sajus, Bull. SOC.Chim. Fr., 1481 (1969). J. Kaloustlan, DSc. Thesis, Unlversite Alx-Marseille ill, 1973. Venezuelian CONICIT Fellow. On sabbatical leave from Department of Chemisw, Lowell University, Mass. 01854.
0
P
C
Henri Arzoumanian,* Rafael Lopez Al~arez*~ W Albert D. Kowalak,3° Jacques Metzger Figure 1. ORTEP drawing of the structure of hydrid0-1,3-(1,1,3,3-tetramethyldisiloxanyl)carbonylbis(triphenylphosphine)iridium( 111). IPSOI, UniversitL Aix- Marseille III Rue H . Poincari. St-JLrBme, 1301 3-Marseille, France Received February 2, 1977 TMDS to give a pale yellow solution, from which a bright yellow powder can be isolated. This substance is thermally labile and rapidly darkens at room temperature under a nitrogen atmosphere. The powder decomposes at 135-140 "C and its ' H NMR spectrum shows a phenyl multiplet at 13 7.2 Catalysis of Siloxane Metathesis by (1 5) and a methyl singlet at 0.2 (6). No RhH peak is observed Cyclometalladisiloxanes.Mechanistic Similarities in the IR. The exact nature of this complex is not yet estabto Olefin Metathesis Catalysis lished, although the IR spectrum in the SiOSi region resembles those of the platinum and palladium metallocycles. Sir: The molecular structure of the iridium metallocycle (11) has We wish to report that small-ring metallocycles of type been determined by x-ray d i f f r a ~ t i o nFigure .~ 1 is an ORTEP I catalyze the disproportionation of 1,1,3,3-tetramethyldisi- drawing of the structure of the inner coordination sphere. The hydrogen presumably sits in the vacant coordination site below \/ the basal plane. The IrSiOSi ring is folded along the S i 4 i axis /Si\ so that the displacements from the mean plane of the four L"M\ o, atoms are Ir (-0.04), Si (+0.06), Si (+0.06), and 0 (-0.08) A. The iridium is also displaced 0.26 A out of the basal P2Si2 plane toward the carbonyl group. The Ir-Si bond distances are I essentially identical at 2.40 A and are just slightly longer than the Ir-P distance, 2.38 A. Hence, the Ir-Si distances appear loxane (TMDS) into dimethylsilane and higher siloxane olito be normal, since the covalent radii of P and Si are within 0.04 gomers (eq 1). 8,of each other, as judged by a variety of P-X and Si-X bond ( n 1)TMDS length^.^ The Si-0 bond lengths are 1.67 and 1.70 8,and appear to be slightly longer than Si-0 bonds in unstrained siMe2SiH(OSiMe2),0SiHMe2 nMe2SiH2 loxanes (av Si-0 = 1.63-1.6.5 (1) E'D, E' The angles associated with the IrSiOSi ring reflect the strain In this reaction strong Si-0 bonds are broken and re-formed in this system. The internal angles are 99.6' (SiOSi), 97.5' (IrSiO), and 64.6' (SiIrSi). In an ideal octahedral complex, at room temperature in a neutral milieu. To our knowledge, the SiIrSi angle would be 90', so that the observed angle rethis represents the first observation of Si-0 bond rearrangeflects the small bite angle of the SiOSi chelate. The SiOSi ments under such mild conditions.1,2 angle is also greatly compressed. In linear and higher cyclic Eaborn et aL3 prepared the first complex of type I, siloxanes, the SiOSi angle falls in the 130- 160" range.5 The LzPt(SiMezOSiMez), by refluxing a benzene solution of large SiOSi angle in siloxanes has been ascribed to the effects TMDS with L2Pt(C2H4) (L = Ph3P). We have prepared the of (p-d) K bonding, so that a decrease of this angle may reflect palladium analogue from TMDS and L2PdC12. The metallosome loss of (p-d) K back-donation from oxygen. This in turn cycle, L2Pd(SiMe20SiMe2), mp 142 'C dec, is obtained in would lead to a weakening (and lengthening) of the Si-0 bond, 20-30% yield following purification by column chromatogas observed. raphy over Florisil ('H NMR 6 7.2 (15, Ph), 0.1 (6, Me)). The iridium metallocycle, L2Ir(CO)(H)(SiMe20SiMe2)(11), was The catalytic effect of metallocycles I on excess TMDS is remarkable in that catalytic amounts of these metallocycles prepared by stirring a benzene solution of TMDS with Vaska's compound at room temperature for -20 min. Complex I1 melts induce a disproportionation of TMDS into dimethylsilane and at 150 "C dec and exhibits vco and V I ~ Hbands at 1950 and higher polysiloxanes, E'D,E' (eq 1). In addition, the rhodium complex gives cyclic, D3 and D4, oligomers. The platinum and 2030 cm-I, respectively. The methyl resonances of I1 occur palladium metallocycles are poor catalysts for eq 1 . The rates as two equally intense singlets at 6 0.2 and 0.4, showing that are low and the catalytic effect diminishes after a few turnthe methyl groups are in nonequivalent environments in soluovers. On the other hand, the iridium and rhodium catalysts tion. seem to be indefinitely active, the reactions are clean and rapid Wilkinson's catalyst, L3RhC1, also reacts readily with
7\
+
-
+
Journal of the American Chemical Society
A ) . 5 3 6
/ 99:lS /
July 20, 1977
