Other Methods for Estimating H Positions

There have appeared in the literature several reports on calculating probable H positions based on a consideration of intramolecular steric interactions between nonbonding atomsb. This method assumes that the geometry of the rest of the molecule (the non-hydrogen portion) is known. 

Sheldrick and Yesinowski40) have recently applied nematic phase nmr data to elucidate the H positions in H3Ru3(CO)9(CCH3), using the heavy atom positions derived from X-ray data. It is in principle an accurate method which does not require large crystals the only difficulties are that many hydrides react with nematic liquid crystals, and that some molecular symmetry is desirable41). 

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