2,3‐Bis(diarylphosphanyl)‐1,4‐diazadienes: P,P Coordination of Pd^II, Pt^II and a Nickelacyclopentanone with Subsequent Formation of Quinoxalines by a Ring‐Closure Reaction at the Periphery

Abstract

The solid-state structures of several 2,3-bis(phosphanyl)-1,4-diazadiene ligands of the general formula RN= C(PPh 2 )−C(PPh 2 )=NR (B: R = 4-tolyl; C: R = 4-tert-butylphenyl; D: R = mesityl) were determined by single-crystal X-ray diffraction. The ligands B and C are nonplanar and lie between the (E) and the (Z) form (N=C−C=N is 99.5°in B, 94.0°in C, and 128.2°in D). In the presence of air, B is oxidized to its corresponding phosphane oxide. Reaction of D with elemental sulfur yields the corresponding phosphane sulfide. Furthermore, ligand C reacts with [PtCl 2 (cod)] and [PdCl 2 (CH 3 CN) 2 ] to form mononuclear complexes (1 and 2, respectively) in which the two P atoms are bound to the metal center. X-ray structural analysis showed that in both complexes the 1,4-diazadiene functionality at the periphery had undergone a ring-closure reaction with one of the aromatic N-substituents thus resulting in a quinoxaline ring. The bulkier ligand D reacts with [PdCl 2 (CH 3 CN) 2 ] to form the monon-

A new set of nickelacyclic carboxylates (“nickelalactones”) containing pyridine as supporting ligand: synthesis, structures and application in C–C– and C–S– linkage reactions

“…1). The bond lengths and bond angles are quite normal and are comparable with those of similar complexes [12,42,43].…”

Synthesis and Coordination Chemistry of Iminophosphanes

“…Reaction with 1 d (R 1 = i Pr, R 2 =Ph), which is labile above −20 °C,14 gave isolable 2 d ( δ 31 P=3.7 ppm) and on its deprotonation a 1.3:1.0 mixture of E ‐ 3 d and Z ‐ 3 d (59 %; δ 31 P=5.1 and −9.7 ppm, respectively; Δ G ( Z ‐ 3 d – E ‐ 3 d )=2.6 kcal mol −1 ). The molecular structure of 3 d shows an imine bond (1.278(5) Å), a C1P1 single bond (1.856(4) Å),11d and an E ‐configuration (Figure 1, left) 16. Apparently, rapid isomerization occurs as the crystals were grown from an E / Z ‐mixture, indicating the absence of co‐crystallization, and the same mixture was regained on redissolving the crystals of E ‐ 3 d .…”

Phosphanyl Methanimine (PCN) Ligands for the Selective Trimerization/Tetramerization of Ethylene with Chromium

“…Separately, trimethylsilylphosphines are prepared in a facile one-pot procedure from either phosphine or chlorophosphine precursors. Subsequent reaction of the chosen trimethylsilylphosphines with the desired imidoyl chlorides affords the target PCN ligands in high yields . Although 1-phosphanyl methanimines and their coordination chemistry with Au, Rh, and Ir have recently been described, the ligands were prepared using a more-complex, less-flexible synthesis strategy.…”