Hydride bridged complexes preparation

The C—H—C bond is not linear, the angle being about 170° according to high-level MO calculations. Several bridged cycloalkyl carbocations of the type 2 have been prepared [236]. Complexes between a number of alkyl cations and alkanes have been detected in mass spectrometric experiments [235]. The nonclassical structure of the ethyl cation, 3, may be cited as another example of hydride bridging (for a discussion, see ref. 55). 

By the action of LiAlH4 on the halide (or in the case of Be on the dialkyls) a number of other hydrides have been prepared, including the dihydrides of Be, Zn, Cd, and Hg, trihydrides of Ga, In, and Tl, and CuH. Some of these are extremely unstable, those of Cd and Hg decomposing at temperatures below 0°C. Pure crystalline BeH2 has not been prepared, but a crystalline amine complex has been made for which the bridged structure (a) has been suggested Be—H bridges have... 

Treatment of 203 with PMe3 affords [ Ru(H)(pz)(cod) 2(PMe3)], 204, in which the neutral pyrazole ligand is replaced by trimethylphosphine (151). Further examples of ruthenium complexes containing bridging pyrazolate and hydride ligands were prepared (152, 153) from the ruthenium(II) precursor [Ru(H )(cod)(NH2NMe2)3](PF6). 

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