Synthesis of palladium and platinum complexes containing the multidentate ligands PPh2CH2(tBu)=N-N=C(R)Q (R = H, Me; Q=2-pyridine, 2-thiophene, o-BrC6H4).: Crystal structure of [PtMe{PPh2CHC(tBu)NNCMe(2-py)-κ3N,N′,P}] and [PdBr{PPh2CH2C(tBu)=N-N=CHC6H4}-κ3C,N,P]

The reaction of PPh2CH2C('Bu)=NN=CMe(NC5H4) (1) with [Pt2Me4(mu-SMe2)(2)] gave the six-membered metallacycle [PtMe2(PPh2CHC(Bu-t)NNCMe(2-py)-kappa(2)N,P}] (4) which was converted into [PtMe(PPh2CHC(Bu-t)NNCMe(2-py)-kappa(3)N,N',P}] (5) at elevated temperature. Treatment of the methyl platinum complex 5 with an excess of MeI gave [PtMe2I(PPh2CHC(Bu-t)NNCMe(2-py)-kappa(3)N,N',P}]. A similar reaction of PtMe2(cod) with [PPh2CH2C(Bu-t)=NN=C(HSC4H3] (2) also afforded PtMe2(PPh2CH2C('Bu)NNC(H)SC4H3-kappa(2)N,P} (7). The prolonged heating of 7 led to decomposition rather than the cycloplatination product. The treatment of 2 with PtCl2(cod) in the presence of NEt3 gave the deprotonated platinum(II) complex Pt{PPh2CH=C('Bu)N-N=C(H)SC4H3-kappa(2)N,P}(2)] (8) containing an ene-hydrazone backbone. The cyclopalladated metallacycle [PdBr{PPh2CH2C(Bu-t)-N-N=CHC6H4}-kappa(3)C,N,P] (9) has been prepared by the oxidative addition of the o-halo-substituted phosphino hydrazone derived from PPh2CH2C(Bu-t)=N-N=C(H)(o-BrC6H4) (3) to Pd-2(dba)(3). These new complexes have been characterized by H-1-, C-13-, and P-31-NMR, and elemental analyses. The molecular structures of 4, 5 and 9 have been determined by a single-crystal X-ray diffraction study. (C) 1999 Elsevier Science S.A. All rights reserved.