Photolysis of Ru3

Table I. Photofragmentation Quantum Yields for the 405 run Photolysis of Ru3(CO)y2 in Different Solutions (25°C)a...

First Order Rate Constants for Decay of Transients Seen by Longer Wavelength (A rr > 390 nm) Flash Photolysis of Ru3(C0)]o in Cyclohexane Solutions with Various Added Ligands a... 

The diyne cluster 10 is formed in good yield from the low-temperature photolysis of Ru3(CO)i2 with FcC=CC=CFc, whereas reaction at slightly higher temperatures affords diruthenium products coupled with two diyne fragments.21... 

Oxidative addition to either an individual Ru atom or across a Ru-Ru bond reduces the molecular symmetry from D3JJ to C2v The weak band at 2109 cm in the HRu3(CO)io(OSi)(ads) spectrum is assigned to symmetric Aj mode and is consistant with a product of C2v symmetry (71). There is no indication in the HRu3(CO)io(OSi)(ads) spectra of a band assignable to a terminal Ru-H vibration. Rather, the photoproduct spectra are equivalent to a series of Ru and Os oxidative addition products, HM3(CO)ioL (L = SR, OH, NO, and OSi), where addition across the metal-metal bond has been established (66,68,69). Thus, UV photolysis of Ru3(CO)i2(ads) leads to the surface grafted species, where a surface silanol group has... 

Photochemical reactions of Ru3(CO)i2 and Os3(CO)i2 with nitrogen hetero-cycles have been studied, with substitution products being formed in most cases. For example, with pyridine the ruthenium compound forms the ortho-metallated complex Ru3H(CO)i i(CsH4N), while the osmium compound gives the simple substitution product Os3(CO)n(py). The novel dihydrido triruthenium cluster H2Ru3(CO)io can be synthesized by photolysis of Ru3(CO)i2 under an atmosphere of dihydrogen. 

Photolysis of Os3(CO),2 at 436 nm in benzene was studied by Poe and Sekhar. The product is Os3(CO), (P(OEt),) when P(OEt)3 is added, but Os(CO)4(Ti -octene) and Os2(CO)4(p-T) ,T)-octene) are formed in the presence of 1-octene. The quantum yield increases with increasing concentration of the nucleophile to a limiting value of -0.04 for both nucleophiles. The observations were interpreted in terms of formation of a reactive intermediate, Os3(CO), (n CO). This may undergo substitution or revert to the nonbridged reactant. The mechanism is analogous to that discussed above for the longer-wavelength photolysis of Ru3(CO),2. 

Polynuclear Carbonyl Derivatives.-Variable temperature MAS n.m.r. methods have been used to probe the exchange processes occurring in solid homonuclear carbonyls containing 3 and 4 metal atoms.A quantitative investigation of the chemistry resulting from both continuous- and flash-photolysis of Ru3(C0)i2 has been carried out, and a new polymeric ruthenium carbonyl, Ru(C0)it n prepared from this precursor. The steric and electronic effects in associative substitution reactions of Iri (C0)i2 have also been examined. The combination of two OS3 units to yield an improved route to Ose raft-like clusters has been achieved, and a comprehensive analysis published on the different Mg cores of stacked Mg triangles in the [Mg C0)i8] "... 

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