Magnetic behavior of polycarbosilazane Fe^II, Fe^III and mixed‐valence Fe^II–III chloride metallopolymers

Abstract

FeII, FeIII and mixed‐valence FeII–III chlorides were reacted with poly[N,N′‐bis(dimethylsilyl)ethylenedi‐ amine], [Si(CH3)2NHCH2CH2NH]n, to form the corresponding Fe‐polycarbosilazane macromolecular complexes. The average chain–chain spacing in these materials was estimated from X‐ray diffraction data and found to be 6.94, 7.29, 7.30 and 7.45 Å in metal‐free and FeII, FeIII and FeII–III‐containing polycarbosilazanes, respectively. This demonstrates that FeII, FeIII and FeII–III chlorides are encapsulated between the polycarbosilazane chains. The chain–chain expansions in the divalent FeII and trivalent FeIII chloride macromolecular complexes are comparable, but less than that in the FeII–III chloride analog, which suggests that different chain–chain packings exist in the mixed‐valence macromolecular complex. The magnetic properties of the resulting complexes were investigated by measuring the magnetization in magnetic fields up to 8 kOe and in the temperature range from liquid nitrogen temperature to room temperature. Copyright © 2007 Society of Chemical Industry

Multifunctional Block Copolymer: Where Polymetallic and Polyelectrolyte Blocks Meet

“…7, Supporting Information). There was a slight downfield shift (Δδ = 0.3 ppm) in the19 F{ 1 H} NMR spectrum of the polymer sample, and the resonance broadened as expected for polymers (Figure4). In the subsequent step, this resonance was used as an internal standard for end group analysis of the fluorine tagged polyelectrolyte block (PS-(P + OTf − )).…”

“…Consequently, end group analysis of a block copolymer made from 5 and polymerized 6 (PS(P + Cl − )) by 1 H NMR spectroscopy was not accurate. Therefore, we utilized a tagging strategy, where fluorine atoms were installed on a phosphonium containing styrene (7; Figure 3) and on a RAFT agent (8; Scheme 1) enabling the use of 19 F{ 1 H} NMR spectroscopy for end group analysis.…”

“…The 19 F{ 1 H} NMR spectrum of the RAFT agent 8 showed a singlet resonance at −62.6 ppm (Figure 4). This key 19 F resonance is subsequently used as an internal reference for the end group analysis of the fluorine tagged polyelectrolyte synthesized via RAFT polymerization of 7. Block Copolymer Synthesis.…”

“…The macro-RAFT agent (9) was used to polymerize fluorine tagged phospho-nium-functionalized styrene (7) to prepare the first example of block copolymer consisting of polyelectrolytes and metallopolymers (10; (polyCpCoCb 5 0 -r-PMA 1 5 0 )-b-(PS-(P + OTf − ) m )). 19 F NMR spectroscopy was used for end group analysis of the produced block copolymer and a reliable estimate on molecular weight (M n ) of the polyelectrolyte block was calculated. Salt metathesis reaction of the polyelectrolyte block with gold salt (HAuCl 4 ) resulted in a heterobimetallic block copolymer with a gold decorated polyelectrolyte block and a cobalt containing metallic block (11; (polyCpCoCb 50 -r-PMA 150 )-b-(PS(P + AuCl 4 − ) m ).…”

“…Over the past decade, research to incorporate transition metals into polymers has continually expanded. − Metallopolymers have shown properties distinct from their organic (conventional polymer) and inorganic (transition metal) components and have found potential applications in catalysis, , sensors, − lithography, − magnetic materials, − electrochromic materials, − and as ceramic precursors. ,,, Well-defined metallopolymers with controlled molecular weights and narrow polydispersity indices (PDIs) − have allowed for the development of solution and solid-state self-assembly to fabricate complex and unique nanostructures with metallic domains. − Metal containing nanostructures such as micelles, vesicles, platelets, and rods in solution, and lamella, cylinders, spheres, and gyroids in the solid-state − are used to synthesize well-defined metal nanoparticles via thermal decomposition, ,, radiation treatment, or reduction of metal salts. − …”