Coordination numbers complexes

Phospholide ions can form metal complexes with different coordination numbers / -complexation is characteristic for their aromatic behavior. The first 7 -complex with Mn(CO)3 (7) was reported in 1976. The ring in some cases (e.g., in 7) is not strictly planar. In 7, the P atom is displaced by 0.041 A from the plane of the carbon atoms. The large number of... 

It now appears that any X=Y double bond can be prepared, given an energetic enough research attack Hundreds of these compounds have now been synthesized. The general method has been to involve bulky substituents. In this way the multiple bond chemistry of the heavier nonmetals has resembled attempts to make low-coordination-number complexes (Chapter 12). 

High-coordination-number complexes of 0-keto-enolates continue to be obtained with the metals such as zirconium(IV),8 hafnium(IV),8 cerium(IV),9 and the lanthanons(III),10 the last being tetrakis anionic species. At least one example of a volatile tetrakis 0-keto-enolate salt has been reported,11 Cs[Y(CF3-COCHCOCF3)4]. The ionic charge on the 0-keto-enolate complex has been shown to produce12 a high field nuclear magnetic resonance for anions and low field shifts for cations, relative to the positions observed for the neutral species. 

Oxidation State Electronic Configuration Coordination Number Complex Geometry Example... 

Oxidative addition of Ge—H to a low oxidation-state, low-coordination-number complex has become a fairly general route s to Ge—M bonds for M = Pt, Ir and Rh... 

Coordination number Complex Coordination geometry References... 

PARAMAGNETIC, HIGH-OXIDATION-STATE, AND HIGH-COORDINATION-NUMBER COMPLEXES... 

Steric stabilization of otherwise reactive species is a standard strategy in organometallic chemistry. Steric bulk can permit formation of low electron count, low coordination number complexes, as in the isolable 14e bis-Tv-allyl complex 2.16. In this case, the bulky SiMej groups enforce a syn,anti conformation that minimizes the steric clash between SiMes groups but blocks approach of additional ligands. The 12e paramagnetic. 

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