Tetradecker sandwiches

Many stmctures are possible for the smaller metaHacarboranes and various synthetic strategies are available. Especially noteworthy is the occurrence of triple- and tetradecker sandwich compounds (214). The polyhedral expansion synthetic strategy can also be used with small carboranes (212). Eor instance, the small metaHacarborane /(9j (9-l,l,l-(CO)3-l,2,3-EeC2B4H3 [32761-40-3] (212) is obtained from C2B4Hg upon treatment with Ee(CO)3. 

Mixed cyclopentadienyl-thiadiborolene tetradecked sandwich compounds are available using a novel zinc complex, e.g. ... 

CpCo(MeEt2C3B2Et2)Ni(8-Me-2,3,5-C3B7H9) Trinuclear C3B2 complexes (tetradecker sandwiches) Cobalt S, X, H, B, MS 41... 

CpNi(H3C3B2H2)NiCp Tetradecker sandwiches Fenske-Hall 43... 

Trinuclear 2,3-C2Bz complexes (tetradecker sandwiches) Molybdenum ... 

Iron-centered tetradecker sandwiches, when in contact with oxygen on silica, undergo oxidative fusion with ejection of iron to generate 12-vertex Co2C4B8 clusters.83 The cluster geometry, however, depends on the nature of the substituent X at B(3) in the iron sandwich. When X = H or Cl, the isolated species are of type 62, also obtained directly from C0C2B3 complexes as described in Section 3.01.4.1 64 when X = Me, the cluster produced is 77.84... 

Fig. 33. Crystal structure showing the tetradecker sandwich geometry of Sn (r)5-...

For a tetradecker sandwich electron counts of 40-48 have been observed [25]. An example is provided by 20.21 [25b]. The outer two polyenes are cyclopenta-dienyls while the inner two are (4,5-diethyl)-1,3-diborole ligands and the metals are... 

Open-chain vinylboranes can also act as ligands in the formation of metal complexes. An example is the preparation of compound (36) by the photochemical reaction of iron pentacarbonyl with chlorodivinylborane. Various B-N compounds can be compared to alkenes in their abilities to complex to transition metals. Several new complexes with cyclic diborylethene ligands have been prepared, for example tetradecker sandwich complexes of Co and Fe from (37), a tricarbonylcobalt complex from (38), and a cyclopenta-dienylcobalt complex from (39). ... 

W. Siebert, C. Bohle, and C. Kroger, Angew. Chem., Int. Ed. Engl., 1980,19, 746. Bis( j-cyclo-pentadienyliron-, -thiadiborolene)iron Structure of a rj-CsKs tetradecker sandwich complex. 

Upon heating in vacuo the salt is converted to the heterobimetallic tetradecker sandwich complex (COT )Ce(p,-COT )Yb()t-COT )Ce(COT ) (COT = l,3,6-(Me3Si)3C8H5) according to the spectroscopic results (Edelmann 1995b). 

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