Capped trigonal prismatic geometry

Capped trigonal prismatic, geometry for metal coordination numbers,... 

We may also mention that there are numerous isocyanide complexes. Isoleptic species are obtained smoothly by the reaction of RNC with Mo2(02CCH3)4 and isolated as [Mo(RNC)7](PF6)2, and in other ways, some of which allow preparation of analogous W" complexes. Substitution of RCN ligands by phosphines, phen, bipy, and so on, lead to many other complexes, particularly the types [M(RCN) L7 ]2+. The [MoX2(CO)4]2 compounds react with RNC to give Mo(RNC)sX2. The [Mo(CNR)6I]+ and [Mo(CNR)7]2+ ions can be made by reaction of Mo(CO)6 with RNC and I2 or by alkylation and reduction of [Mo(CN)8]4. Both types have capped trigonal prismatic geometry. 

Among seven-coordinate structures, many involve dike-tonate complexes Ln(diket)3 L these generally have either capped-octahedral or capped trigonal prismatic geometry. A considerable number of complexes with neutral donors (e g. thf) of the type LnX3L4 (X = halide, NCS), however, have structures closest to pentagonal bipyramidal, similarly found in the erbium perchlorate complex with 2,6-dimethyl-4-pyrone (Section 3.7.4). 

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