Mixed Metal Carbonyls

The complexes reviewed in this section contain transition metals from different groups and/or metals from the main groups. 

Clusters which contain two (or more) D-Block metals include a series of new indenyl complexes containing chromium and rhodium atoms the complex (C0)4pe-C(NMe2 )OTi( NMe2) [0C(NMe2) ]2 ( 0)3 prepared by Petz and the anionic iron-iridium clusters [FeIr4(C0) and [Fe2lr4(CO) g] (including their characterisation and structures 

Group 16-containing mixed-metal carbonyl complexes include a study of the stereochemistry of the compounds Fe3(CO)9XY (X, Y = S, Se, or Te) and the selenium-containing clusters 0s5(p-H) (CO) j 5(p -SePh) and Osg(p-H) (CO) 

Clusters containing metals from outside the D-Block are, like last year, quite numerous. Rh2oC2 clusters with a variable number of CO groups and four Au(PPh3) groups have been reported and the solution dynamics of the tin/iron cluster (Et4N)2tSn(Fe2(CO)8)(Fe(CO)4)2] have been explored .  

Iron-containing clusters which incorporate a Group 16 ligand or atom figured prominently in the 1993 literature, as they have in previous years. Huang and Kanatzidis have prepared 

In recent years, the enqihasis in dus section of this chapter has been towards die preparation of metal carbon d conqilexes. Whilst this remains the dominant theme, it was interesting to find that Pomeroy and co-woikers have been cleaving Os-W bonds 

The ihodium-manganese complex RhMn(CO)4(Ph2PCH2PPh2) has been found to react with a number of su hur-containing conqiounds. The authors have prepared a number of new compounds containing terminal or bridging sulphur groups. 

The synthesis and characterisation of the platininn-containii species (PPh3)HPt(/i-PPh2XM CO)M(CO)4 (M = Cr, Mo, W) has been reported by Shao et al The range of rhenium-platinum clusters has been extended by the preparationof the complex [Re3Pt(/L(-H)3(CO)i4]. Osmium-rhodium complexes are also mentioned  

Iron and gold are coupled together in the compound [(Ph3p)2N][Fe3(CO)9(/i -PMeX/i P)]2Au and rhenium is partnered with either rhodium or iridium by Haupt et 

The appearance of tellurium in mixed-metal carbonyl cluster chemistry has been a feature of recent years and the reactions of [Te Feg(CO)24] with dihaloalkanes has now been reported.  

Catalytic and photochemical processes using mixed metal carbonyls are also represented. Tin-cobalt carbonyl compounds have been used as catalysts for ring-opening of oxiranes by secondary and tertiary alcohols 121 and the photochemical reactions of Pt2M4(CO)jg (M=Os, Ru) with cycloocta-1,5-diene under UV irradiation 122,123,124 jjgve been reported. A new rhenium-cobalt complex has been characterised 126 and Pt(cod)2 has been used to prepare new complexes via its reaction with 0 3(CO) jQ(FlCMe)2 26. 

T E Bitterwolf, K A Lott, A J Restand JMascetti,Afrr/./V rsAm.CAein.Soc., 1991, 201,486. 

C Dossi, A Pusi, R Psaro, D Roberto and R Ugo, Materials Chem. andPhys., 1991,29, 191. 

S M Howdle, M Jobling, M Healy and M Poliako AbsLPapersAm.Ckem.Soc., 1991, 

M A Healy, T J Jenkins and M Poliakoff, TRAC - Trends in Analytical Chemistry, 

Gold-phosphine chemistry relevant to this report is published by Kappen et who have prepared the complex 

The F63 triangle opening and closing mechanism in Fe3(CO)9(a -PMLn) (ML = CpFe(CO)2 or CpMn(CO)2) has been investigated . Fe-Co-Ge clusters are also noted .  

A mixed Pt-Rh cluster of corpulent proportions [Pt4Rhjg(CO)35] - has been reported by Fumagalli et aJ . The same groups is responsible for some Re-Ir clusters via addition of tIr(CO)4l to fRe2(p-H)2(CO)g], and new Mi-Bi clusters . Adams has contributed to the swelling numbers of mixed-metal cluster compounds with RugPt 2 (CO) 23(11 -11)2 and other Ru-Pt clusters . A number of osmium-Group VI metal cluster compounds have also been prepared . 

Finally, of interest to workers in catalytic processes using carbonyl clusters, some work on CO hydrogenation catalysts derived from metal carbonyl clusters (ie molybdenum promoted Rh/Si02 and Rh/Zr02) has been published . 

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The limited magnetic measurements of very mixed -metal clusters are summarized in Table XIII. The magnetic behavior of some anti-ferromagnetic very mixed -metal carbonyl clusters (Fig. 82) has been studied by Pasynskii and eo-workers. Temperature dependences of the magnetic susceptibilities of Cr2Co(/t3-S)3(/i-SBu )(CO)2() -C3H4R)2l (R = H. Me) have been determined us-... 

The reaction with [Mn(CO)5]2 or [Co(CO)4]2 also led to mixed-metal clusters.962,963 Osmium-palladium mixed-metal carbonyl clusters were made using the unsaturated cluster [Os3(CO)io(/r-H)2] and the carbido cluster [Os5(/U5-C)(CO)15].964 970 Treatment of [Os3(CO)10Gu-H)2] with [Pd2(/u-dppm)2Cl2] afforded the novel high-nuclearity osmium-palladium mixed-metal carbonyl clusters [Os5Pd6(CO)13( -CO)5(/u-H)2(/u-dppm)2], [Os5Pd6(CO)13(//-CO)6(/u-dppm)2], and... 

Waterman, Susan M., Lucas, Nigel T., and Humphrey, Mark G., Very-Mixed -Metal Carbonyl Clusters. 46 47... 

Suppose a mixed metal carbonyl contains one Mn atom and one Co atom. How many CO molecules would be present in the stable compound What would be its structure ... 

Pakkanen and coworkers—synergistic effects with mixed metal carbonyls. 

Synergistic studies were carried out on mixed metal carbonyl and mixtures of metal carbonyl complexes by Pakkanen and coworkers.94 95 A largely applied research approach, results are reported below in Table 23 for Fe-Ru and Fe Os carbonyl catalysts. Also tested (not shown) were Fc -Co and Fe-Rh carbonyl catalysts, Ru-Co and Ru Rh carbonyl catalysts, and Co-Rh, Co-Ir, and Rh Ir carbonyl catalysts. Typical conditions T = 100 °C Pco = 0.42-0.60 atm pyridine = 2.0-4.0 ml H20 = 0.36 ml. Note that dppe = Ph2PCH2CH2PPh2. The data shown in Table 23 are representative of the TON for their catalysts. 

Catalyst solutions of Fe and Ru or Fe/Ru mixed metal carbonyls were found to exhibit two orders of magnitude higher activity than either the Ru or Fe carbonyl catalysts alone. A weaker synergistic behavior was observed for Fe/Ir mixed metal carbonyls, which were 50% more active. Rh carbonyl catalysts were the most active ( 590 mol H2/mol catalyst per day), but did not display a synergism in combination with other metal carbonyls. 

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