Syntheses and Structures of Zinc Bis(phosphinimino)methanide Complexes

Abstract

Reactions of bis(

A Synthetic Model of Enzymatic [Fe4S4]–Alkyl Intermediates

“…Both exhibit C 3 symmetry in solution as indicated by splitting of the diastereotopic Ar–C H 2 –Ar and Ar–C H 2 –CH 3 resonances. Their 31 P NMR resonances (at 102.1 and 96.0 ppm for 4 and 5 , respectively) are shifted downfield from that of the free ligand 3 (−0.4 ppm), reflecting both the expected downfield shift upon binding a Lewis acidic metal center 32,33 and the population of paramagnetic excited states as is commonly observed in [Fe 4 S 4 ] 2+ clusters; 23,34−38 their room-temperature solution magnetic moments (μ eff = 2.7 and 2.8 μ B , respectively) are consistent with this interpretation and typical of [Fe 4 S 4 ] 2+ clusters. 35,39−41 The 1 H NMR signals corresponding to the −C H 3 and −C H 2 – protons of the ethyl ligand in 5 are observed at −4.6 and 70.0 ppm, respectively, which also indicates the population of paramagnetic excited states.…”

Role of Bis(phosphinimino)methanides as Universal Ligands in the Coordination Sphere of Metals across the Periodic Table

“…The new zinc complexes [{CH­(Ph 2 PNR) 2 }­ZnMe] (R = Dipp ( 80 ), Ph ( 81 )), [{CH­(Ph 2 PNR) 2 }­ZnEt] (R = SiMe 3 ( 82 ), Dipp ( 83 ), Ph ( 84 )), and [{CH­(Ph 2 PNSiMe 3 ) 2 }­ZnPh] ( 85 ) were prepared through the reaction of a neutral ligand ( 1TMS , 1Dipp , or 1Ph ) with either 1 or 2 equiv of ZnR 2 (R = Me, Et, Ph) (Scheme ). , In both cases, the ligand underwent monodeprotonation only, resulting in the formation of a monoanionic ligand. The structures of the complexes 80 – 85 were very similar to each other and monomeric like 75 – 78 and consisted of a six-membered metallacyclic structure in which the ligand acted as a bidentate chelate and the zinc centers adopted distorted trigonal-planar geometry.…”

Synthesis and Structure of a Dimeric Iminophosphorane Stabilized Zinc Carbene: (ZnCR2)2

“…The single deprotonation of the BIPM-H 2 ligand by ZnMe 2 to yield Zn­(BIPM-H)­Me complexes proceeds smoothly already at room temperature . In contrast, the synthesis of Zn carbene complexes of the type ZnCR 2 with doubly deprotonated BIPM ligands is not straightforward.…”

“…The 31 P NMR spectrum only shows one singlet signal at 29.83 ppm, indicating chemical equivalence of the phosphorus atoms at the measuring temperature. Although numerous heteroleptic Zn­(BIPM-H)­R or Zn­(BIPM-H)­X (X = halide) have been reported, complex ( 5 -H) 2 Zn is the first homoleptic complex of the type Zn­(BIPM-H) 2 . Its 13 C and 31 P chemical shift as well as 1 J C–P coupling constant in the CP 2 unit are comparable to those in heteroleptic complexes …”

“…Although numerous heteroleptic Zn­(BIPM-H)­R or Zn­(BIPM-H)­X (X = halide) have been reported, complex ( 5 -H) 2 Zn is the first homoleptic complex of the type Zn­(BIPM-H) 2 . Its 13 C and 31 P chemical shift as well as 1 J C–P coupling constant in the CP 2 unit are comparable to those in heteroleptic complexes …”