Synthesis and structure of (phosphaalkenyl)mercury compounds

Article abstract of DOI:10.1021/om00059a057

The (phosphaalkenyl)mercury compounds (E)-Mes*P=CHHgCl [(E)-4], (Z)-Mes*P=CHHgCl [(Z)-4], (E,E)-(Mes*P=CH)₂Hg [(E,E)-5], and (Z,Z)-(Mes*P=CH)₂Hg [(Z,Z)-5] (Mes* = 2,4,6-tri-tert-butylphenyl) were prepared from (E/Z)-Mes*P=CHLi [(E/Z)-3] or (Z)-Mes*P=CHLi [(Z)-3], respectively, and HgCl₂. The Z isomers (Z)-4 and (Z,Z)-5 were more stable than the corresponding E isomers: (E,S)-5 decomposed and (E)-4 and (E,E)-5 rearranged to the corresponding Z isomers. The X-ray crystal structure determination of (Z,Z)-5 was carried out; crystals are monoclinic, space group P2₁/c with unit-cell dimensions a = 13.8800 (7), b = 14.4938 (6), c = 19.8504 (5) ?, and β = 104.494 (3)°, final R = 0.0497, and R_w = 0.0313 for 2671 reflections with I > 2.5σ(I) and 375 parameters. The results show a double Z configuration with the mercury atom sandwiched between the two phenyl rings; the phenyl rings are slightly bent toward the mercury atom, indicating a stabilizing interaction between these groups. When (Z,Z)-5 was reacted with n-butyllithium, only lithium-mercury exchange was observed.