Group 10-12 Metal Acetylide Complexes

Most of the mixed metal acetylide complexes of this particular group are those associated with Cp, Cp and carbonyl ligands. A number of synthetic studies have been carried out for polynuclear C2 complexes derived from ethynyl and diethyne-diyl iron complexes. Reaction of the ethynyliron complexes [ ( -C5R5)Fe (CO)2 -C = C H] (R = H, 1 R = Me, 2) with [Ru3(CO)i2] in refluxing benzene affords triruthenium /i- j j, j -acetylide eluster eompounds [Ru3(CO)9(/ -H) 

Treatment of 6 with R-alpha-chloropropionic acid results in an addition reaction yielding a /i-hydrido -carboxylato derivative [( 4-C = C)( -H)(/i-K K -CH3CHClCOO)Fe2Ru2Cp 2(CO)8] (15). On irradiation of a THF solution of 6, 

Highly conjugated polycarbon-metal systems, the zwitterionic /i-but-2-yn-l-ylidene-4-ylidyne complex [Ru3(CO)io(/i3-C-C = C-/i-C)Fe2Cp 2(CO)3] (23) and 

The triosmium acetylide cluster, [Os3(/r-H)(/i3-C=CMe)(CO)9] (28) reacts with [Ru3(CO)i2] in refluxing hexane to give the tetranuclear [RuOs3(/i4-HC2Me)(CO)i2] 

Reaction of a dichloromethane solution of cw-[(dppm)2RuCl2] with trans-[(dppm)2(Cl)Os(C = C-/ -C(sH4-C = CH)] and NaPFg gives a vinylidene complex, which converts to tra 5-[(dppm)2(Cl)Os(C = C-p-CfsH4-C = C-Ru(Cl)(dppm)2] 

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Metal-acetylide complexes have been used as a unit of organometallic polymers that have metallic species in the main chain [20]. Representative examples are metal-poly(yne) polymers (19) of group 10 metals depicted in Scheme 5. These polymers are easily prepared from M(PR3)2Cl2 (M=Pt, Pd) and dialkynyl compounds catalyzed by Cu(I) salts in amine. Recently, this synthetic method was successfully applied to the construction of metal-acetylide dendrimers. 

Measurements made by DFWM on Group 10 metal bis(acetylide) complexes are listed in Table VIII. Although results cannot be directly compared to those cited earlier, internal comparisons within the series are valid. These reveal that hyperpolarizability decreases progressing down the group for phenylacetylide examples (as observed with other acetylide complexes see earlier), but that larger nonlinearities are observed for butadiynide complexes of the heavier metals. The complexes exhibit a high-order intensity dependence, characteristic of multiphoton resonant enhancement for these complexes this is possibly due to three-photon resonant enhancement, as Amax is, in all cases, close to 3o>. 

Addition of acid to the /i3-acetylide complexes (92 M = Ru or Os) results in the formation of 93 (M = Ru or Os) by an acid-induced migration of the hydroxy group from carbon to metal (137). Only the orange osmium derivative could be isolated, and this was structurally characterized as the /i3-di phenylpropadienylidene complex shown. 

One of the characteristic features of the metal-bis-acetylide complexes in chemical reactions is that they undergo a ligand exchange reaction with metal dihalides in amines in the presence of a cuprous halide catalyst to produce a monoalkynyl-metal-monohalide complex (Eq. IS) which results from selective cleavage of the metal-carbon bond weakened by the /ram-alkynyl group in the bis-acetylide... 

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