Olefin Metatheses in Metal Coordination Spheres: Development of Gyroscope-like trans-Spanning Bis(pyridine) Complexes and Organometallic pi-Adducts of Conjugated Polymers

Abstract

The olefin metathesis reaction has become one of the most powerful carbon-carbon bond forming reaction in synthetic chemistry. This work has expanded the utility of olefin metathesis in metal coordination spheres in three major directions (1) the synthesis and characterization of trans-spanning bis(pyridine)PtCl2 complexes, (2) the developme-adducts of polyacetylene (PA), and (3) the development of regioregular -adducts of poly(phenylene-vinylene) (PPV).

Chapter I gives a brief overview of olefin metathesis and previous applications to organometallic substrates.

Chapter II details the synthesis of pyridine ligands containing alkenyl substituents, 2-NC5H4(CH2O(CH2)nCH=CH2) (n = 1, 2), 3-NC5H4(CH2O(CH2)nCH=CH2) (n = 1-5, 8, 9), and 3,5-NC5H3(p-C6H4O(CH2)7CH=CH2)2. Metalation of the new ligands with PtCl2 affords the corresponding trans-bis(pyridine)dichloroplatinum complexes, trans-PtCl2(2-NC5H4(CH2O(CH2)nCH=CH2))2 (n = 1, 2), trans-PtCl2(3-NC5H4(CH2O(CH2)nCH=CH2))2 (n = 1-5, 8, 9), and trans-PtCl2(3,5-NC5H3(p-C6H4O(CH2)7CH=CH2))2. Ring-closing metathesefirst generation catalyst followed by hydrogenations with Pd/C afford the title complexes trans-PtCl2-(NC5H4(CH2O(CH2)2n+2OCH2)H4C5N)] (n = 1, 2), trans-PtCl2-(NC5H4(CH2O(CH2)2n+2OCH2)H4C5N)] (n = 4, 8, 9), and trans-PtCl2-(NC5H3(p-C6H4O(CH2)12O-p-C6H4)2H3C5N)]. Reactions with methylmagnesium bromide afford trans-PtCl(CH3)(3-NC5H4(CH2O(CH2)nCH=CH2))2 (n = 2, 8) and trans-PtCl(CH3-(NC5H4(CH2O(CH2)nOCH2)H4C5N)] (n = 10, 18), which feature dipolar rotators. Low temperature NMR spectra in the latter remained facile on the NMR time scale in CDFCl2 at -120 degrees Celsius.

Chapter III focuses on the application of ROMP with organometallic monomers to form metal pi-adducts of polyacetylene. The new complex (n4-benzene)Cp*Ir has been synthesized, crystallographically characterized, and evaluated in the ROMP reaction. Monomers (n4-benzene)CpIr, [(n6-COT)CpRu][PF6], and (n4-COT)Fe(CO)3 were also evaluated in the ROMP reaction. ROMP of (?4-benzene)CpIr with Grubbs' first generation catalyst afforded the conductive regioregular polymer CpIr-PA.

Chapter IV focuses on the synthesis of the divinyl benzene complexes [Cp*Ir(C6H4(CH=CH2)2)][BF4]2 and [Cp*Ru(C6H4(CH=CH2)2)][OTf] and their polymerization via ADMET to afford PPV systems. Treatment of divinyl benzene ed the conductive regioregular polymers [Cp*Ir-PPV][BF4]2n and [Cp*Ru-PPV][OTf]n. The photophysical properties of the new -metal adducts of PPV exhibit blue-shifts relative to typical PPVs and retain strong UV absorption.