The difficulty of coordinating mutually trans phosphine and aryl ligands in palladium complexes and its relation to important coupling processes. Syntheses and crystal structures of a family of palladium phosphino, triflato, perchlorato, and aquo-8-(arylazo)aryl complexes

The reaction between [Pd(C6H3N=NR-2, X-5)Cl](2) and phosphines gives [Pd(C6H3N=Nto-2,Me-5)Cl(L)] [To=C6H4Me-4, L=PEt3 (1a), PPh2Me (1b)] or trans-[Pd(C(6)H(3)N(2)To-2,Me-5)CIL2] (L=PEt3 (2a), PPh2Me (2b), L-2 = bis(diphenylphosphino)methane=dppm (2c)) or trans-[Pd(C6H3N2X-2, R-5)Cl(mu-dppm)](2) (X=Me, R=To (3a); X=H, R=Ph (3b)), depending on the molar ratio of the reagents. Tl(OTf) (OTf=O3SCF3), AgClO4, or AgSbF6 react with 1a,b, 2a, 2c, or 3a to give, variously, [Pd(C6H3N=NTo-2,Me-5)(Y)(L)] (L=PEt3, Y=TfO (4a); L=PPh2Me, Y=TfO (4b), ClO4 (4b')), trans-[Pd(C(6)H(3)N(2)To-2,Me-5)(OTf)(PEt3)(2)] (5), [Pd(C(6)H(3)N(2)To-2,Me-5)(eta(1)-dppm)(eta(2)-dppm)]TfO (6), or [Pd(C6H3N=NR-2,X-5)(eta(2)-dppm)]Y (X=Me, R=To, Y=TfO(7a)). Complexes [Pd(C6H3N=NR-2,X-5)(eta(2)-dppm)]SbF6 (X=Me, R=To (7a'); X=H, R=Ph (7b)) can be prepared by reacting [Pd(C6H3N=NR-2,X-5)Cl](2) with AgSbF6 and dppm. Complex 4b' reacts with PPh2Me to give [Pd(C(6)H(3)N(2)To-2,Me-5(PPh2-Me)(3)]ClO4 or 7b lead to different products. From 4, and insertion into the Pd-OTf bond of one molecule of water gives [Pd(C6H3N=NTo-2,Me-5(OH2 ... OTf)(PEt3)] (9) while substitution of the acetone molecule by two water molecules occurs in the second case to give [Pd(C6H3N=NTo-2,Me-5){(mu(3)-OH2)(... OClO3)(... OH2)}(PPh3)] (10). Finally, ready oxidation in the air of 7b gives [Pd(C6H4N=NPh-2)(eta(2)-dppmO)]SbF6 (11) [dppmO=bis(diphenylphosphino)methane monoxide]. [Pt(PPh3)(3)] reacts with [Hg(C(6)H(3)N(2)To-2, Me-5)Cl] to give trans-[Pt(C(6)H(3)N(2)To-2,Me-5)Cl(PPh3)(2)] (12), which in turn reacts with Tl(OTf) to give [Pt(C6H3N=NTo-2,Me-5)(PPh3)(2)]TfO (3). Crystal structures of 2c . 1/2CH(2)Cl(2), 4b', 5, 6, 7a, 9, 10, and 11 . 2MeOH have been determined.