Synthesis, solution and solid-state structure of Pd(II), Pt(II), Ir(III) and Zn(II) complexes with 5-pyridyl substituted N-methyl isoxazolidines

Pd(II), Pt(II). Zn(II) and Ir(III) complexes with 5-pyridine substituted N- methyl isoxazolidines (4-(2-methyl-3-phenylisoxazolidin-5-yl)-pyridine (L-1 ), 2-(2-methyl-3-phenylisoxazolidin-5-yl)-pyridine (L-2), 2-(2-methyl-3-fer rocenylisoxazolidin-5-yl)-pyridine (L-3)) have been prepared and characteri zed by H-1, C-13, and P-31 NMR. The configurations of coordinated isoxazoli dines have been assigned by the analysis of NMR coupling constants and by n uclear Overhauser measurements through 2D-ROESY experiments. The molecular structures of [Cp*Ir(L-2)Cl][BPh4] (6) (Cp*-pentamethylcyclopentadienyl) an d trans-[PdCl2(L-3)PEt3] (8) have been established by means of X-ray crysta llography. The crystal structure of 6 consists of piano stool geometry with respect to the Ir(III) center with N-bidentate coordinated ligands. The si x-membered chelate ring formed by Ir(1), N(1), C(5), C(6), O(1), N(2) posse sses a 'twist-tub' conformation. The crystal structure of 8 consists of neu tral square planar Pd(II) complexes. L-3 is coordinated in a monodentate ma nner via the pyridine nitrogen atom. The isoxazolidine fragment of both com pounds has an envelope conformation. NMR data are consistent with an O,N-bi dentate coordination of L-2 for [Zn(L-2)Cl-2] (5), while L-1 act as a monod entate ligand through the nitrogen atom of the pyridine in [Zn(L-1)(2)Cl-2] (4). (C) 2001 Elsevier Science Ltd. All rights reserved.