Synthese und Koordinationschemie hemilabiler P,N‐Hybridliganden mit terminalen 2‐Pyridyl‐Donorgruppierungen

Abstract

Synthesis and Coordination Chemistry of Hemilabile P,N‐Hybride Ligands with Terminal 2‐Pyridyl Donor Groups*P,N‐hybride ligands 1–7 containing terminal 2‐pyridyl donor groups have been obtained by base‐catalyzed addition of diphenylvinylphosphane or 2‐vinylpyridine to primary or secondary phosphanes [2‐Py‐(CH2)2‐PR′H (R′ = H, Ph), HMeP‐(CH2)3‐PMeH] or by alkylation of organolithium phosphides, R2P‐(CH2)3‐PMeLi or 2‐Py‐(CH2)2‐PR′Li (R = Ph, iPr; R′ = H, Ph), with 2‐(2‐chloroethyl)pyridine or di‐tert‐butylphosphetanium bromide. Upon reaction with NiBr2 3 H2O or K2MCl4 (M = Pd, Pt) the phosphanes (L) of type 2‐Py‐(CH2)2‐P(R′)‐(CH2)m‐PR2 (1, 3, 6) form square planar Ni(II), Pd(II), and Pt(II) complexes of composition MX2(L) (10–14). With NiBr2 and K2MX4 the tripod type phosphane 2 forms square pyramidal complexes [MX(2)]X (M = Ni, Pd; X = Cl, Br; 15, 16). An X‐ray structural analysis of [NiBr(2)]+Br− (15) reveals a distorted square pyramidal coordination geometry at Ni(II), the 2‐Py donor being in apical position with a long NiN bond [2.270(15) Å]. The tetradentate ligand 7 forms Ni(II), Pd(II), and Pt(II) complexes MX2(7) which for M = Pd, Pt show dynamic behaviour by exchange of the terminal Py donor groups. With [RhCl(COD)]2 the tridentate ligands L (1 and 3) yield complexes of composition RhCl(L) (20, 21). The structure of 20 has been determinated by X‐ray diffraction. The ligand 3, acting in a tridentate manner, is coordinated to Rh(I) in a distorted square‐planar arrangement with a normal RhN distance [2.145(3) Å].