Synthesis and reaction chemistry of platinum(II) amide complexes
Description
Cationic ammine complexes trans-(PtR(NH$\sb3$)L$\sb2$) ClO$\sb4$ (R = H, Me, Ph; L = PPh$\sb3$, PEt$\sb3$, PPh$\sb2$Me, PCy$\sb3$) have been prepared from trans-PtR(ClO$\sb4$)L$\sb2$ and ammonia. Complexes trans-(PtR(NH$\sb3$)L$\sb2$) ClO$\sb4$ (R = H, Me; L = PPh$\sb3$, PEt$\sb3$, PPh$\sb2$Me) react with amide ion to give syn and anti- (PtR($\mu$-NH$\sb2$)L) $\sb2$ via the intermediate trans-PtR(NH$\sb2$)L$\sb2$. When R = Me the dimers are stable, but for R = H reductive elimination occurs to give PtL$\sb2$. The structure of anti- (PtMe($\mu$-NH$\sb2$)(PPh$\sb3$)) $\sb2$ (monoclinic, C2/c, a = 22.592(5), b = 11.844(3), c = 29.403(6)A, $\beta$ = 116.43(2)$\sp\circ$ shows a bent dimeric structure. Complexes trans- (PtR(NH$\sb3$)(PCy$\sb3$)$\sb2$ClO$\sb4$ (R = H, Me, Ph) react with amide ion to give stable monomeric complexes trans-PtR(NH$\sb2$)(PCy$\sb3$)$\sb2$. Bridge cleavage of (PtMe($\mu$-NH$\sb2$)L) $\sb2$ with L (L = PPh$\sb3$, PEt$\sb3$) gives cis-PtMe(NH$\sb2$)L$\sb2$. Complexes trans-PtR(NH$\sb2$)L$\sb2$ (R = Me, Ph) are readily protonated by strong and weak acids to yield trans- (PtR(NH$\sb3$)(PCy$\sb3$)$\sb2$) X (X = SO$\sb3$CF$\sb3$, OH). The complex trans-PtPh(NH$\sb2$)(PCy$\sb3$)$\sb2$ reacts with MeI or CH$\sb2$=CHCH$\sb2$Cl to give trans-PtPhX(PCy$\sb3$)$\sb2$ (X = I, Cl) respectively. Carbon dioxide reacts with trans-PtPh(NH$\sb2$)(PCy$\sb3$)$\sb2$ to give the insertion product trans-PtPh(OCONH$\sb2$)(PCy$\sb3$)$\sb2$. Reactions of trans-PtMeClL$\sb2$ (L = PPh$\sb3$, PCy$\sb3$) with LiNMe$\sb2$ yield hydride complexes trans-PtMeHL$\sb2$. The complex trans-Pt(CF$\sb3$)Cl(PPh$\sb3$)$\sb2$ reacts with LiNMe$\sb2$ to give products derived from Pt(PPh$\sb3$)$\sb2$. The complex trans- (PtMe(THF)(PPh$\sb2$C$\sb6$F$\sb5$)$\sb2$) ClO$\sb4$ prepared from trans-PtMeCl(PPh$\sb2$C$\sb6$F$\sb5$)$\sb2$ and AgClO$\sb4$, reacts with hydroxide ion to give the cyclometalated complex trans-PtMe(2-OC$\sb6$F$\sb4$PPh$\sb2$)(PPh$\sb2$C$\sb6$F$\sb5)$. The crystal structure of trans-PtMe(2-OC$\sb6$F$\sb4$PPh$\sb2$)(PPh$\sb2$C$\sb6$F$\sb5)$ has a monoclinic P2$\sb1$/c cell with a = 12.437(2), b = 25.749(8), c = 10.788(2) A, $\beta$ = 102.35(1), Z = 4. Reacting trans- (PtMe(THF)(PPh$\sb2$C$\sb6$F$\sb5$)$\sb2$) ClO$\sb4$ with methoxide ion gives trans-PtMe(OMe)(PPh$\sb2$C$\sb6$F$\sb3$(OMe-2,6)$\sb2$)$\sb2$. Treating this complex with water gives trans-PtMe(2-OC$\sb6$F$\sb3$(OMe-6)PPh$\sb2$)(PPh$\sb2$C$\sb6$F$\sb3$(OMe-2,6)$\sb2$). Heating a mixture of triphenylphosphine, bromopentafluorobenzene and nickel bromide at 200$\sp\circ$C, followed by hydrolysis of the melt, gives the phosphonium salt (Ph$\sb3$P(C$\sb6$F$\sb4$H-4)) Br. The use of D$\sb2$O in the hydrolysis yields (Ph$\sb3$P(C$\sb6$F$\sb4$D-4) Br. Hydroxide ion reacts with the phosphonium salt to give P-C bond cleavage