The Difficulty of Coordinating MutuallytransPhosphine 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-2-(arylazo)aryl Complexes

The reaction between [Pd(C 6 H 3 N NR-2, X-5)Cl] 2 and phosphines gives [Pd(C 6 H 3 N NTo-2,Me-5)Cl(L)] [To = C 6 H 4 Me-4, L = PEt 3 ( 1a ), PPh 2 Me ( 1b )] or trans -[Pd(C 6 H 3 N 2 To-2,Me-5)ClL 2 ] (L = PEt 3 ( 2a ), PPh 2 Me ( 2b ), L 2 = bis(diphenylphosphino)methane = dppm ( 2c )) or trans -[Pd(C 6 H 3 N 2 X-2, R-5)Cl(μ-dppm)] 2 (X = Me, R = To ( 3a ); X = H, R = Ph ( 3b )), depending on the molar ratio of the reagents. Tl(OTf) (OTf = O 3 SCF 3 ), AgClO 4, or AgSbF 6 react with 1a, b, 2a, 2c, or 3a to give, variously, [Pd(C 6 H 3 N NTo-2,Me-5)(Y)(L)] (L = PEt 3, Y = TfO ( 4a ); L = PPh 2 Me, Y = TfO ( 4b ), ClO 4 ( 4b ‘)), trans -[Pd(C 6 H 3 N 2 To-2,Me-5)(OTf)(PEt 3 ) 2 ] ( 5 ), [Pd(C 6 H 3 N 2 To-2,Me-5)(η 1 -dppm)(η 2 -dppm)]TfO ( 6 ), or [Pd(C 6 H 3 N NR-2,X-5)(η 2 -dppm)]Y (X = Me, R = To, Y = TfO ( 7a )). Complexes [Pd(C 6 H 3 N NR-2,X-5)(η 2 -dppm)]SbF 6 (X = Me, R = To ( 7a ‘); X = H, R = Ph ( 7b )) can be prepared by reacting [Pd(C 6 H 3 N NR-2,X-5)Cl] 2 with AgSbF 6 and dppm. Complex 4b ‘ reacts with PPh 2 Me to give [Pd(C 6 H 3 N 2 To-2,Me-5)(PPh 2 Me) 3 ]ClO 4 ( 8 ). Attempts to obtain single crystals of 4a, [Pd(C 6 H 3 N NR-2,X-5)(PPh 3 )(Me 2 CO)]ClO 4, or 7b lead to different products. From 4, an insertion into the Pd−OTf bond of one molecule of water gives [Pd(C 6 H 3 N NTo-2,Me-5(OH 2 ···OTf)(PEt 3 )] ( 9 ) while substitution of the acetone molecule by two water molecules occurs in the second case to give [Pd(C 6 H 3 N NTo-2,Me-5){(μ 3 -OH 2 )(···OClO 3 )(···OH 2 )}(PPh 3 )] ( 10 ). Finally, ready oxidation in the air of 7b gives [Pd(C 6 H 4 N NPh-2)(η 2 -dppmO)]SbF 6 ( 11 ) [dppmO = bis(diphenylphosphino)methane monoxide]. [Pt(PPh 3 ) 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(PPh 3 ) 2 ] ( 12 ), which in turn reacts with Tl(OTf) to give [Pt(C 6 H 3 N NTo-2,Me-5)(PPh 3 ) 2 ]TfO ( 13 ). Crystal structures of 2c· 1 / 2 CH 2 Cl 2, 4b ‘, 5, 6, 7a, 9, 10, and 11·2MeOH have been determined.