Clusters cuboidal

The trinuclear [Fe3S4] site has been described as either a linear cluster, (3a) (shown in Figure 3), or cuboidal cluster, (3b) (shown in Figure 4), and models of each have been prepared and studied. It is unclear whether the linear cluster is... 

Stmctural data of the cuboidal model compound and of protein sites indicate that the cuboidal cluster is stmcturally closely related to the cubane cluster and shares many of the same stmctural properties. 

The linear and cuboidal clusters also demonstrate reactivity to produce four-iron [Fe4 S4] and heterometal [MFes S4] cnbane clusters. " It has not been established whether the linear cluster remains intact in the reaction to form a cnbane clnster. The cuboidal cluster, however, readily bonds iron and many other metals at the voided site to form a cnbane clnster with minimal structural change. Biologically, this assembly of the [Fe4S4] cluster by addition of iron to a cuboidal [Fe3S4] core has been shown to be the regulatory step in the action of IRP-1 (see Metalloregulation). 

Electrochemical studies of the mixed metal cuboidal clusters revealed that, like [Mo4S4(H20)i2] +, they could be reversibly reduced and oxidized in one-electron steps. The comer-shared double cube [Mo7S8(H20)ig] + is described in the Section 7.3.5. 

The cuboidal cluster [Mo3PdS4(tacn)3Cl] [PFeJs (14) is an efficient catalyst for the stereoselective addition of carboxylic acids to electron-deficient alkynes and the cyclization of alkynoic acids to enol lactones (Eq. 1 ). ... 

The impetus for the development of iron-sulfur cluster chemistry over the last three decades derives largely from the occurrence of iron-sulfur clusters in an extensive variety of proteins and enzymes.Five cluster types (l)-(5) have been demonstrated by protein crystallography and are shown in Figure 1. Clusters (l)-(3) represent the fundamental set found in proteins (ferredoxins) from a variety of prokaryotic and eucaryotic sources. Rhomb-like cluster (1) is especially prevalent in green plants. Cuboidal cluster (2) and cubane-type cluster (3) are found in bacterial sources... 

The trinuclear incomplete cuboidal cluster [Mo3S4(H20)9]", first prepared in the mid-1980 s, combines a high degree of stability with quite unusual reactivity. One route for the preparation of [Mo3S4(H20)9]" from Na2[Mo202S2 (cys)2] -4H20 is now well established, with yields typically 25%. In 1992... 

Two subsections are added. One is 6.2.5 on reactions involving chalcogeno Mo and W clusters, which is subdivided further into polyoxohomopolymetalates polyoxoheteropolymetalates chalcogeno (S, Se) cuboidal clusters, general [S, Se clusters], homometallic and [S, Se clusters], heterometallic. The second added subsection is 8.1.5 on reactions involving the Prussian blues . 

Chalcogeno (S, Se) cuboidal clusters, general. One source of hydrated M03S4... 

Chalcogeno (S, Se) cuboidal clusters, homometallic. Reductants including Mg, V, [MoCU] ", Mo2Cl8]" and HPH2O2 in variorrs conditions convert Mo3S4" ... 

---