One-Dimensional And 2-Dimensional Solution And Solid-State Nmr-Studies Of Dinuclear And Trinuclear Optically-Active Ferrocenylphosphine Complexes Of Mercury(Ii)

Reaction of the 1,1'-bis(diphenylphosphino)ferrocenyl ligand, 1, containing the chirotopic side-chain (R)-CH-(CH3)N(CH3)CH2CH2N(CH3)2 in the 2-position, with HgX2 derivatives affords the cationic complexes [Hg3X4-(1)2]X2 (X = Cl, Br, 1), 2a-c, respectively, in which the phosphorus atom, P1, on the disubstituted Cp ring and the two tertiary nitrogens are coordinated to one metal center and the phosphorus, P2, on the second Cp ring, is coordinated to a different metal center. The structural nature of these compounds is supported by multinuclear NMR including, most importantly, Hg-199 NMR. Low-temperature P-31 studies, combined with 2-D P-31 exchange spectroscopy, suggest the existence of species with one and two mercury atoms of related structure. These complexes could be recognized in solution using both Hg-199 and P-31 NMR. The chemistry for the analogous CN- derivative, 2d, is also discussed. Conventional as well as two-dimensional COSY and EXSY (spin-diffusion) cross-polarization, magic-angle spinning solid-state P-31 spectra were recorded for the complexes 2a,b,d, as well as for the model compounds HgX2(1,1'-bis(diphenylphosphino)ferrocene) (X = Cl, CN). The complex 2d, X = CN, is interesting in that the solid-state phosphorus NMR results suggest a different structure than that found in solution at low temperature. The 3-D solution structures of the complexes of the three halides, with respect to the conformation of the coordinated side chain, were determined using 1- and 2-dimensional P-31 and H-1 NMR methods and are discussed in relation to the structure of 1.