Carbonyls, metal Semibridging complexes

Carbonylation metal salt reduction by CO at high pressure with M-CO bond formation Polyhydride complex of the type L MHj (x > 3) Semibridging CO unsymmetrically bridged CO... 

Crabtree et al. created a very different classification scheme in which he systematically classifies the linear semibridging carbonyls into four subclasses depending on M2 and structures [5]. Type I complexes consist of early transition metals (up to group 6 Certain complexes with group 6 metals may also be classified... 

Further, Fenske-Hall calculations were able to show that Crabtree s type 111 complexes (which contain unsaturated very late transition metals that traditionally are not expected to be good at donating backbonding electrons, e.g., Cu(NR3)2 or Au (PR3)) may be able to interact more strongly with the linear semibridging carbonyls [93, 94]. 

More recently, a second and rarer type of semibridging carbonyl has been recognized, one in which the semibridging CO remains linear as the second metal approaches (4.8). Triply bridging CO groups are also known in metal cluster compounds, for example, (Cp Co)3( x -CO)2. These have CO stretching frequencies in the range of 1600-1730 cm. PdSiO, a very unstable molecule seen only at low temperatures, is the only SiO complex known. ... 

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