Synthesis and nonlinear optical properties of carbonylrhenium bromide complexes with conjugated pyridines

Carbonylrhenium bromide complexes fac-Br(OC)(3)ReL2 (3a,b, 4a,b) and cis-Br (OC)(4)ReL (5a,b) with conjugated pyridines L = Fc-CH=CH-p-C5H4N (1a), Fc-C H=CHC(CH3)=CHCH=CHCH=C(CH3)CH=CH-p-C5H4N (1b), 1,1'-Fc(-CH=CH-p-C5H4N)(2) ( 1c), p-Me2N-C6H4-CH=CHCH=CH-p-C5H4N (2a), and p-Me2N-C6H4-CH=CHC(CH3)=CHCH= CHCH=C(CH3)-CH=CH-p-C5H4N (2b) have been synthesized. The structures of 4a and 5a have been determined by X-ray diffraction analysis. Compound 4a exhi bits a remarkable quadratic hyperpolarizability.