New Palladacycles Containing Terdentate [C,N,O]n- (n = 0, 1, 2) or Tetradentate [N,C,O,N′]n- (n = 1, 2) Ligands.: The First 1,2-dihydroquinazoline-4-yl Complexes

The reaction Of IC6H4{NHC(Me)CHC(O)Me]-2 (IAr) with [Pd-2(dba)(3)] center dot dba (Pd(dba)(2), dba = dibenzylideneacetone) gives, in the presence of bidentate ligands (NN)-N-boolean AND (1: 1: 1), cis- [PdI(Ar)((NN)-N-boolean AND)] ((NN)-N-boolean AND = 4,4'-tert-butyl-2,2'-bipyridine = (t)Bubpy (1), N,N,N',N'-tetramethylethylenediamine = tmeda (2)). These complexes react with PPh3 (1:2) to give trans-[PdI(Ar)(PPh3)(2)] (3) or with TITfO (TfO = CF3SO3) to give [Pd{C,C-C6H4 {NH=C(Me)CHC(O)Me}-2)((NN)-N-boolean AND)] TITfO (TfO = (t)Bubpy (4), tmeda (5)), which, in turn, react with neutral monodentate ligands (L, 1: 1) to give complexes [Pd(Ar)((NN)-N-boolean AND)(L)] ((NN)-N-boolean AND = (t)Bubpy, L = PPh3 (6), (NN)-N-boolean AND = tmeda, L = PPh3 (7), (BuNC)-Bu-t (8)). The reaction of IAr with Pd(dba)(2) and RNC (R = Xy, Bu-t) in 1:1:2 molar ratio produces a mixture containing [Pd2I2(CNXy)(4)] (9, XY = C6H3Me2-2,6) or trans-[PdI2] [C(=(NHBu)-Bu-t)Ar} ((CNBu)-Bu-t)] (10), respectively, but using an excess of RNC (1:1:5 molar ratio), complexes trans-[PdI{C(=NR)Ar}(CNR)(2)] (R = Bu-t (11), Xy (12)) are obtained instead. Complex 5 reacts with XyNC (1: 1) to give the dimeric complex [Pd{mu-N,C,N',O-N(Xy){=CC6H4{NC(Me)CHC(Me)O}-2}}](2) (13), which reacts with excess HTfO to give [Pd [mu-N,C,N',O-N(Xy){=CC6H4{N=C(Me)CH2C(O)Me}-2}}](2)(TfO)(2) (14a) or with neutral monodentate ligands (L) to give neutral mononuclear pincer complexes [Pd{C,N,O-C(=NXy)C6H4{NC(Me)CHC(Me)O}-2}(L)] (L = PPh3 (15), (BuNC)-Bu-t (16a), XyNC (17)), which react with excess of HTfO to give the corresponding dicationic [Pd[C,N,O-C(=NHXy)C6H4{N=C-(Me)CH2C(O)Me}-2}(PPh3)(TfO)(2) (18) or monocationic pincer derivatives [Pd[CNOC(=NHXy)C6H4 I NC(Me)CHC(Me)O 1 -2 1 (CNR)]TfO (R = tBu (19), Xy (20)), respectively. The reaction of complex 11 or 12 with AgClO4 (1:1) or that of 14a with PPh3 (1:2) affords [Pd{C,N,O-C(=NHR)C6H4{ NC(Me)CHC(Me)O}-2}L]X (X/R/L = ClO4/Bu-t/(BuNC)-Bu-t (21), ClO4/Xy/XyNC (22), TfO/ Xy/PPh3 (23)), analogues of 19 or 20, respectively. The reaction of 21 with Na2CO3 (2: 1) allowed the synthesis of [Pd{C,N,O-C(=(NBU)-B-t)C6H4{NC(Me)CHC(Me)O}-2}((CNBu)-Bu-t)] (16b). The reaction of 1 or 3 with HI and XyNC in 1: 1: 2 or 1: 1: 1 molar ratio, respectively, produces the first 1,2-dihydroquinazoline-4-yl complexes trans- [PdI2{C(=NXy)C(Me){CH2C(O)Me}NHC6H4-2} (L)] (L =XyNC (24), PPh3 (25)). The crystal structures of complexes 1, 3, 5, 7, 10, 13, 14a, 17, 21, 22, and 24 have been determined. Single crystals of complex [Pd{mu-O,N,C,N'-OC(Me)CHC(Me)NC6H4C=NXy}{mu-N,C,N',O-N(Xy) {=CC6H4{NC(Me)CH2C(Me)O}-2}}]TfO (14b) were obtained alongside those of 14a, and the corresponding crystal structure was also solved.