Formation and reactivity of metal-ligand bonds: platinum(I) dimers and cobalt and chromium alkyls
(Pt/sub 2/(..mu..-dppm)/sub 2/Cl(PPh/sub 3/))/sup +/ is formed from a rate-limiting bimolecular reaction of PPH/sub 3/ with (Pt(..mu..-dppm)/sub 2/Cl/sub 2/) in CH/sub 2/Cl/sub 2/. Alternatively, it and its bromo and chloro derivatives can be formed from the reaction of halides with (Pt(..mu..-dppm)/sub 2/-PPh/sub 3/)/sub 2/)/sup 2 +/ by (a) rate-limiting PPH/sub 3/ dissociation, or (b) rate-limiting Pt/sub 2/(..mu..-dppm) ring opening at a Pt-P bond. Formation of product by (b) occurs after the formation of two observable intermediates, one of which, (Pt/sub 2/)eta/sup 2/-dppm)(..mu..-dppm)X(PPh/sub 3/))/sup +/, is readily characterized by /sup 31/P(/sup 1/H) NMR spectroscopy. Rates of these ligand substitution reactions are very sensitive to the anions present in solution. Atropisomers due to hindered rotation around the Pt-PPh/sub 3/ bond of (Pt/sub 2/(..mu..-dppm)/sub 2/Cl(PPh/sub 3/))/sup +/ are caused by phenyl-phenyl repulsions and can be distinguished by /sup 31/P(H) NMR spectroscopy. Such repulsions also retard the rate of positional interchange of axial and equatorial substitutents on its Pt/sub 2/(..mu..-dppm)/sub 2/ ring as observed by /sup 1/H NMR spectroscopy. Several correlations between /sup 195/Pt-/sup 31/P coupling constants and Pt-P and Pt-Pt bond lengths were observed. The synthesis, characterization, and reactivity of((Pt/sub 2/(..mu..-dppm)/sub 2/Cl)(di-eta/sup 2/-P/sub 4/))/sup 2 +/ is reported. This complex is a dimer of platinum dimers bridged by tetra-phosphorus. One platinum of each dimer is bound to two phosphorus atoms of P/sub 4/. The formation and reactivity of the metal-carbon bonds in benzylcobalamin and chromium alkyls, ((H/sub 2/O)/sub 5/CrR/sup 2 +/; R = CH/sub 2/Ph, CH(CH/sub 3/)OC/sub 2/H/sub 5/, CH/sub 2/OCH/sub 9/), were also investigated.
- Research Organization:
- Iowa State Univ. of Science and Technology, Ames (USA)
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 5815827
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
CHROMIUM COMPLEXES
CHEMICAL PREPARATION
CHEMICAL REACTIONS
COBALT COMPLEXES
HETEROCYCLIC COMPOUNDS
ORGANIC PHOSPHORUS COMPOUNDS
ORGANOMETALLIC COMPOUNDS
PLATINUM COMPLEXES
DIMERS
COMPLEXES
ORGANIC COMPOUNDS
SYNTHESIS
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties
400301 - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)