Cyclometallated complexes of Pd II and Mn I with N,N-terephthalylidenebis(cyclohexylamine)

Abstract

Treatment of N,N-terephthalylidenebis(cyclohexylamine), 1,4-(CyNCH) 2C 6H 4 (Cy = cyclohexyl) with palladium(II) acetate in glacial acetic acid gave the monocyclometallated dimer complex [{P d[4-(CHO)C 6H 3CHN Cy](O 2CMe)} 2] ( 1) which was shown to have a free formyl group on each phenyl ring by IR and 1H and 13C-{ 1H} NMR spectroscopy. Treatment of 1,4-(CyNCH) 2C 6H 4 with [MnMe(CO) 5] in octane gave the doubly cyclometallated complex [(OC) 4 MnN(Cy)C(H)C C 6H 2C(H)N(Cy)M n(CO) 4] ( 2). Reaction of 1 with aqueous sodium chloride, bromide or iodide gave the monocyclometallated dimer complexes [{ Pd[4-(CHO)C 6H 3C(H)N Cy](X)} 2] [X = Cl ( 3), Br ( 4), or I ( 5)]. Complexes 1, 3 and 4 react with amines to give the corresponding cyclometallated dimer complexes [ Pd{4-(CyNCH)C 6H 3C(H)N Cy}(O 2CMe)] 2 ( 6) and [{ Pd[4-(CyN=CH)C 6H 3C(H)=N R](X)} 2] [X = Cl ( 7), X = Br ( 8) R = Cy; X = Cl, R = 2,4,6-Me 3C 6H 2 ( 9)] with an uncoordinated C=N group on each phenyl ring. Treatment of 3, 4 or 5 with thallium acetylacetonate gave the cyclometallated monomer compound [ Pd{4-(CHO)C 6H 3C(H)=N Cy}-(CH 3COCHCOCH 3)] ( 10) with a chelating 2,4-pentanedionate group. Treatment of 3, 4 or 5 with tertiary phosphines in a dimer/ phosphine 1:2 or 1:4 molar ratio afforded the cyclometallated [ Pd{4-(CHO)C 6H 3C(H)=N Cy}(X)(L)] ( 11–18) and noncyclometallated [Pd{4-(CHO)C 6H 3C(H)=NCy}(X)(L) 2] ( 25–31) (X=Cl, Br, or I; L=PPh 3, PPh 2Et, PPhEt 2, or PPh 2Me). Reaction of 11–13 with cyclohexylamine (L=PPh 3) gave the non-cyclometallated compounds [Pd{4-(CyN=CH)C 6H 3C-(H)=NCy}(X)(PPh 3)(NH 2Cy)] ( 19–21) with two uncoordinated C=N groups whereas reaction of 14–18 with cyclohexylamine (L = PPh 2Et, PphEt 2, or PPh 2Me) gave the cyclometallated compounds [ Pd{4-(CyN=CH)C 6H 3C(H)=N Cy}(X)(L)] ( 22–24). Compounds 25 and 29 gave [Pd{4-(CyN=CH)C 6H 3C)(H)=NCy}(Cl)(L) 2] ( 32,33) (L= PPh 3, or PPh 2Et) when treated with cyclohexylamine. IR and 1H, 13C and 31P NMR data are discussed.