Bridged phosphine complexes cobalt

Chelation of ixo-maleonitriledithiolate (imdt) has been structurally characterized in the octahedral cobalt(III) complex trmw-[Co(imdt)2(P(ra-Bu)3)2], formed via reaction of cobalt(II) ion with K2(imdt) in the presence of the phosphine.1037 Simple chelating thiolates such as SCH2CH2S not only form mononuclear compounds, but participate in bridging in clusters such as [Co3(SCH2CH2S)3(PEt3)3]3+ (243).1038... 

We have mentioned that the structural parameters of C2H4 bridged compounds can vary over a wide range. Whereas most examples reported do not have metal-metal bonds, there is one conspicuous exception. Theopold and Bergman succeeded in synthesizing the propane-1,3-d iyl cobalt derivative 125 from the radical anion [(t) ,-C5H5)Co(/z-CO)12 and 1,3-dibromopropane (98, 295) in 40 5 yield. This compound is best described as a dimetallacyclopentane, and its chemistry (thermolysis and reaction with CO and phosphines Scheme 34) supports this view. Formation of cyclopropane (100°C or I2/25°C) is probably the most remarkable feature of this cyclic system. Simple C—C bond formation has never been observed before in ligand-induced or thermal reactions of either mono- or binuclear cyclopentadienylcobalt complexes. The architectural details of... 

Reactions with phosphines are the central theme in papers dealing with P-C bond cleavage in CH2(PPh2)2 a new low-pressure synthesis of Co2(CO)g(PR3)2 complexes and cobalt carbonyl complexes with bridging diphosphine ligands ... 

In their earlier studies, Halpern and coworkers [171] investigated the oxidation mechanism of phosphines with different metal complexes. Thus, in the cobalt(ll)-mediated reaction, in a first step an oxygen-phosphine exchange was assumed, which led to an 02-bridged binuclear Co complex (Scheme 2.51). In a second step, external phosphine was converted into the corresponding phosphine oxide. 

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