Exercise 3 Metalligand Lewis acidbase interactions a Triflat

Exercise 3. Metal-ligand (Lewis acid-base) interactions (a) Triflates, sulfonates and triflimides are described as pseudohalides. Compare the electronegativity (estimated not absolute), acidity/basicity and metal bonding characteristics of each of these species to a representative halogen (e.g., CI). Based on this analysis, why do you think these groups are considered “pseudohalides\"? SO2CF3 O-S-CFa O-S-Ar SO2CF3 Exercise 3. Metal-ligand (Lewis acid-base) interactions (continued) (b) Phosphine boranes (the Lewis acid-base adducts of phosphorous-derived Lewis bases and boron Lewis acids) can be deprotonated using typical strong bases (e.g., lithium diisopropylamide) Me CH2 BH LDA Me Me i. Provide a structure (with formal charges) for the phosphine-borane. ii. In the absence of BH3, t-butyldimethylphosphine is unreactive toward LDA. How is borane functioning to acidify the phosphine? ii Explain the regioselectivity of the deprotonation. (Why is one of the methyl groups deprotonated instead of the BH3 group?) (c) As we will see in our discussion of coordination chemistry, nitrogen and phosphorous are ubiquitous ligands for a wide variety of metal ions. Compare the strengths of the interactions for NMes and PMes with Ti4+ and Ag*.

Solution

Solution:

Pseudohalides:

These are the polyatomic compounds, Its chemical properties are similar with the halogen componds but the halogen compounds are of the same group elements. These Pseudohalides are different group of elements and these in poly atomic state only acts as halides.