Bridged phosphine complexes chromium

Chromium complexes (continued) organohalide activation, 5, 381 with phosphine-based supporting ligands, 5, 365 porphyrin-ligated derivatives, 5, 364 pyridinebis(imine) ligand derivatives, 5, 361 salen-ligated complexes, 5, 379 surface chemistry on oxides, 12, 525 tetradentate [04] compounds, 5, 352 tetradentate thioether derivatives, 5, 365 thiolate-bridged, Fe- and Rh complexes, 5, 308 with Ti(IV), 4, 627... 

The only example of Si H M agostic interaction supported by a phosphorus bridge was discovered by Driess et al. in the complexation of a silylated triphosphine ligand to a chromium tricarbonyl complex [Eq. (20)].143,144 A bigger metal (M = Mo) or smaller substituent at silicon (R = Ph) leads to the normal triphosphine complexes. The presence of a Si H "M interaction in 59 is deduced from the lack of C3 symmetry (evident from NMR), the red shift of the IR band for the coordinated Si-H bond (1994 cm-1 vs. 2142 cm-1), and the observation of a reduced Si-H coupling (135.7 Hz for the coordinated Si-H bond vs. 210.9 and 228.6 Hz for the free Si-H bonds). The X-ray structure determination of 59 shows that one of the phosphine ligands is tilted away from the chromium atom so that the... 

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