Hydridotris(3,5-dimethylpyrazolyl)borate Tungsten Alkyne Complexes for Nonlinear Optics

Deprotonation of the propargyl site of racemic or enantiomerically
pure Tp‘(CO)IW(C6H5C⋮CCH3) (Tp‘=
hydridotris(3,5-dimethylpyrazolyl)borate) yields an
η2-allenyl anion
which has been reacted with a series of aldehydes and ketones
possessing electron-donating
substituents. Elimination under either acidic or basic conditions
generates chiral trans
conjugated enynes. Characterization has been accomplished by NMR,
IR, UV−vis, and
elemental analysis. Additionally, X-ray diffraction has been used
to structurally characterize
racemic
Tp‘(CO)IW(C6H5C⋮CCHC(CH3)C5H4FeC5H5).
The structural analysis reveals a
centrosymmetric space group (P1̄); cell dimensions of
a = 10.690(5) Å, b = 13.360(7) Å,
c =
15.392(7) Å, α = 92.57(6)°, β = 101.70(5)°,
and γ = 100.97(4)°; Z = 2 molecules/unit cell;
and
Rw = 4.7% and R = 3.9%.
Second harmonic generation of the enynes has been measured
by
the Kurtz powder technique.