Structural investigation of phenol-phosphonic amides

Sessions C665To compare the strengths of these interactions and to investigate their geometrical preferences, the approach suggested by Lommerse et al. [1], using the normalized distance R HX and the spatially normalized distance vs. angle (R HX 3 vs. 1 -cos[180 -(D-H•••X)]) plot, was applied.The study implies: (1) Even if the N-H(s) were deprotonated / substituted, O-H(s) and C-H(s) in the molecules could serve as hydrogen bond donors.O-H(s) are normally better donors than N-H(s), while C-H(s) build weaker interactions.(2) No notable differences were found among F, Cl and Br in both examined criteria.(3) In general, the capability as hydrogen bond acceptor is X -> X-M > X-C, which is complied with results of others [2].(4) Important counter anions in coordination chemistry, such as BF 4 -, PF 6 -and SbF 6 -, exhibit comparable hydrogen bond acceptor capabilities like transition metal-halides.(5) Special attention is drawn to MX 4 2-type counter anions (templates).The several cases recorded show exclusively the formation of much stronger hydrogen bonds compared to normal metal-halides.Their possible roles in complex synthesis and nucleation are still unclear, further studies with theoretical methods would follow.(6) Although CH 2 Cl 2 / CHCl 3 are often used and are observed in structures, X-C is seldom involved in hydrogen bonding.In the rare cases at most very weak interactions were built.While on the other hand the increased acidity of the C-H(s) makes them possible hydrogen bond donors.