Aminomethylierung von Thiophosphorsäuredialkylester-, Phosphon- bzw. Thiophosphonsäurealkylesteramiden,Phosphon- bzw. Thiophosphonsäurediamiden und Diphenylthiophosphinsäureamid

Aminomethylation of Phosphoro-, Phosphono-, Phosphinoamidoates and -amidothioates Dialkylphosphoroamidates, alkyl-phosphonoamidates and phosphonoamidothioates react with C₂H₅O? CH₂? NR₂ and HCOH/HNR₂, respectively, as like as a N-aminomethylation forming the corresponding derivatives of the general formula R₂P(X)? NR′? CH₂? NR″₂? R = alkoxy, alkyl, aryl; R′ = H, alkyl; X = O, S; R″ = alkyl, cycloalkyl —. Under the same conditions phosphonodiamidoates and phosphonodiamidothioates yield RP(X)-[NR′? CH₂? NR″₂]₂ or RP(X)? NHR′? (NR′? CH₂? NR″₂) only. These compounds are not formed by interactions of RP(X)(NR′? CH₂OH)₂ with sec. amines. The aminomethylation of (C₆H₅)₂P(S)NH₂ gives unexceptional [(C₆H₅)₂P(S)]₂N? CH₂? NR′₂. The i.r. and ¹H-n.m.r. data of the prepared compounds, which can't be distilled mostly, are discussed.     

Synthesis and properties of azobenzene‐containing poly(1‐alkyne)s with different functional pendant groups

1‐Alkynes containing azobenzene mesogenic moieties [HC?C(CH₂)₉? O? ph? N?N? ph? O? R; R = ethyl ( 1 ), octyl ( 2 ), decyl ( 3 ), (S)‐2‐methylbutyl ( 4 ), or (S)‐1‐ethoxy‐1‐oxopropan‐2‐yl ( 5 ); ph = 1,4‐phenyl] were synthesized and polymerized in the presence of a Rh catalyst {(nbd)Rh⁺[B(C₆H5)₄]^?; nbd = 2,5‐norbornadiene} to yield a series of liquid‐crystalline polymers in high yields (e.g., >75%). These polymers had moderate molecular weights (number‐average molecular weight ≥ 12,000), high cis contents in the main chain (up to 83%), good thermal stability, and good solubility in common organic solvents, such as tetrahydrofuran, chloroform, and dichloromethane. These polymers were thoroughly characterized by a combination of infrared, nuclear magnetic resonance, thermogravimetric analysis, differential scanning calorimetry, polarized optical microscopy, and two‐dimensional wide‐angle X‐ray diffraction techniques. The liquid‐crystalline behavior of these polymers was dependent on the tail group attached to the azobenzene structure. Poly‐ 1 , which had the shortest tail group, that is, an ethyl group, showed a smectic A mesophase, whereas poly‐ 2 , poly‐ 3 , and poly‐ 5 , which had longer or chiral tail groups, formed smectic C mesophases, and poly‐ 4 , which had another chiral group attached to the azobenzene structure, showed a chiral smectic C mesophase in both the heating and cooling processes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4532–4545, 2006     

Preparation and properties of triorganostannylmethyl 2,3:5,6-di-O-isopropylidene-α-D-mannofuranosides; pesticidal and fungicidal activities of triphenylstannyl-carbohydrate derivates

The synthesis of trioganostannylmethyl 2,3:5,6-di-O-isopropylidene-α-D-mannofuranoside (compound 3, R*OCH₂SnR₂R′:R?R′?Me or Ph) from D-mannose is reported. The compound 3 (R?R′?Ph) is transmetallated by PhLi to compound 5, R*OCH₂Li, Which can be trapped by HgCl₂ [as (R*OCH₂)₂Hg] and by ketones, R³COMe [as compound 7, R*OCH₂CR³MeOH]. Two stereoisomers of this compound (7a, R³?Ph) were formed in a ratio of 40:60, indicating some asymmetric induction, arising from the chiral R* moiety. Reactions of compound 3, (R?R′?Ph), with I₂, HO₂CCF₃ and Cl₂PtCOD result in Ph–Sn bond cleavage and formation of compound 3 with R?Ph; R′?I, OCOCF₃ and Cl respectively. Reactions of compound 3 (R?R′?Me) with electrophiles can lead to cleavage of either of both types of C–Sn bonds present (e.g. by I₂, Br₂, Cl₂PtCOD or SnCl₄) or to attack at the C₅–C₆ protecting group with release of acetone (e.g. by CF₃CO₂H, SO₂ or CH₃COCl). Pesticidal and fungicidal activities of compound 3(R?R′?Ph) as well as of 1,2:5,6-di-O-isopropylidene-3-O(triphenylstannylmethyl)-α-D-glucofuranose (compound 2, R?Ph) and methyl 4, 6-O-benzylidene-2-deoxy-2-triphenylstannyl-α-D-altropyranoside (compound 1, R?Ph) are reported.     

Synthesis and properties of the polythiourethanes obtained by the cationic ring‐opening polymerization of cyclic thiourethanes

The cationic ring‐opening polymerization of a five‐membered thiourethane [3‐benzyl‐1,3‐oxazolidine‐2‐thione (BOT)] with boron trifluoride etherate afforded the corresponding polythiourethane with a narrow molecular weight distribution in an excellent yield. The molecular weight of the polymers could be controlled by the feed ratio of the monomer to the initiator. A kinetic study of the polymerization revealed that the polymerization rate of BOT (1.3 × 10^?2 L mol^?1 min^?1) was two times larger than that of the six‐membered thiourethane [3‐benzyltetrahydro‐1,3‐oxazolidine‐2‐thione (BTOT); 6.8 × 10^?3 L mol^?1 min^?1], and the monomer conversion obeyed the first‐order kinetic equation. These observations, along with the successful results in the two‐stage polymerization, supported the idea that this polymerization proceeded in a controlled manner. Block copolymerizations of BOT with BTOT were also carried out to afford the corresponding di‐ and triblock copolymers with narrow molecular weight distributions. The order of the 5% weight loss temperatures was as follows: poly(3‐benzyltetrahydro‐1,3‐oxazolidine‐2‐thione) [poly(BTOT)] > poly(BTOT₅₄‐b‐BOT₄₆) > poly(3‐benzyl‐1,3‐oxazolidine‐2‐thione) [poly(BOT)]. This indicated that an increase in the BTOT unit content raised the decomposition temperature. The order of the refractive indices was poly(BOT) > poly(BTOT₅₄‐b‐BOT₄₆) > poly(BTOT₅₄‐b‐BOT₄₆‐b‐BTOT₅₀) > poly(BTOT); this was in accord with the order of the sulfur content in the polymer chain. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4795–4803, 2006     

Synthesis of liquid crystalline poly(1‐pentyne)s and fabrication of polyacetylene–perovskite hybrids

Poly(1‐pentyne)s containing biphenyl and phthalimido pendant groups with different spacer lengths {P 1 (m); ? [HC?C(CH₂)₃O? Biph? OCO(CH₂)_mN(CO)₂C₆H₄]_n? , Biph?4,4′? biphenylyl; m = 7, 10} are synthesized in satisfactory yields by WCl₆‐Ph₄Sn catalyst in toluene at elevated temperatures. The structures and properties of the polymers are characterized and evaluated by IR, NMR, TGA, DSC, POM, and XRD analyses. Both of the polymers are thermally stable (T_d ≥ 300 °C) and exhibit nematicity at high temperatures. Their phthalimido groups are converted into amino groups by hydrolysis, which can, after acidification, complex with lead(II) bromide to furnish polyacetylene–perovskite hybrids in high yields. The organic components contribute good solubility to the hybrids, while the perovskite framework induces the polyacetylene chains to align within the inorganic sheets. The hybrids emit a strong UV light of 374 nm upon photoexcitation, whose quantum yield increases with an increase in the spacer length. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3538–3550, 2006     

Synthesis and light‐emitting properties of platinum‐containing oligoynes and polyynes derived from oligo(fluorenyleneethynylenesilylene)s

A series of blue‐light‐emitting oligo(fluorenyleneethynylenesilylene)s (OFESs) of the general formula HC?CRC?C(EC?CRC?C)_mEC?CRC?CH (E = SiPh₂, SiMe₂, or SiMe₂? SiMe₂; m = 0–2; R = 9,9‐dihexylfluorene‐2,7‐diyl) and their phosphorescent platinum‐containing oligoynes and polyynes were synthesized and characterized. The solution properties and regiochemical structures of this new structural class of organosilicon‐based polyplatinayne polymers {trans‐[? Pt(PBu₃)₂C ?CRC?C(EC?CRC?C)_mEC?CRC?C? ]_n} were studied with IR and NMR (¹H, ¹³C, ²⁹Si, and ³¹P) spectroscopy. The optical absorption and photoluminescence spectra of these metallopolymers were examined and compared with their discrete oligomeric model complexes. Our studies led to a novel approach of using the sp³‐silyl moiety as a conjugation interrupter to limit the effective conjugation length in metal polyynes, which could boost the phosphorescence decay rates essential for light‐energy harvesting from the triplet excited state. The influence of the heavy platinum atom and the group 14 silyl unit possessing different side‐group substituents on the thermal and phosphorescence properties was investigated in detail. We also established the goal of studying the evolution of the lowest singlet and triplet excited states with chain length m of OFESs and the nature of E in these metallopolymers. This work indicated that the phosphorescence emission efficiency harnessed through the heavy‐atom effect of platinum in the main chain did not change very much with oligomer chain length m but generally decreased with the E group in the order SiMe₂ > SiMe₂? SiMe₂ > SiPh₂. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4804–4824, 2006     

Water‐swollen highly oxygen permeable membranes: Analytical technique and syntheses

A generally accepted method for the determination of high oxygen permeabilities (Dk >100 barrers) of water‐immersed membranes is unavailable. We designed and developed a generally applicable method, together with simple equipment, to measure the oxygen permeability up to Dk ～800 barrers of highly oxygen permeable membranes in contact with water. A theory of the methodology is also presented, giving particular attention to the boundary layer effect and the edge effect. The practical applicability of our technique is demonstrated by preparing and using highly oxygen permeable water‐logged membranes, such as polydimethylsiloxane and polysiloxane copolymers important for medicine. According to our measurements, the Dk's of polydimethylsiloxane, poly(dimethylsiloxane_0.80‐co‐diethylsiloxane_0.20), and poly(dimethylsiloxane_0.84‐co‐diphenylsiloxane_0.16) are 792 ± 26, 505 ± 10, and 249 ± 10 barrers, respectively. Evidently, the oxygen permeabilities of polysiloxanes are strongly reduced by substituting the ? OSiMe₂? repeat unit with the structurally similar ? OSiEt₂? and ? OSiPh₂? repeats. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3491–3501, 2005     

The behaviour of beryllium μ4-oxo-μ-carboxylates under electron impact

The electron impact mass spectra of eight polynuclear beryllium complexes Be₄O(RCO₂)₆ (R?H, CH₃, C₂H₅) and Be₄O(RCO₂)₅OR′ (R?CH₃, R′?H, CH₃, C₂H₅, C₃H₇; R?C₂H₅, R′?C₂H₅) are reported. The major fragmentations involve the elimination of (RCO)₂O (RCOOR′) or Be(RCO₂)₂ (Be(RCO₂)OR′) from the ions [M? L]⁺ and of {(R? H)CO}, (R′? H), H₂O and BeO from the lighter ions. The fragmentation patterns are practically independent of the organic groups present and can be rationalized by stereochemical considerations.     

Theoretical study on the insertion reactions of the germylenoid H2GeClMgCl with RH (R = F, OH, NH2)

The insertion reactions of the germylenoid H₂GeClMgCl with RH (R = F, OH, NH₂) have been studied by using the DFT B3LYP and QCISD methods. The geometries of the stationary points on the potential energy surfaces of the reactions were optimized at the B3LYP/6-311+G(d, p) level of theory. The calculated results indicate that all the mechanisms of the three insertion reactions are identical to each other. The QCISD/6-311++G(d, p)//B3LYP/6-311+G(d, p) calculated potential energy barriers for the three insertion reactions of R = F, OH, and NH₂ are 164.62, 193.30, and 200.73 kJ mol^?1, and the reaction energies for the three reactions are ?57.46, ?35.65, and ?22.22 kJ mol^?1, respectively. Under the same situation, the insertion reactions should occur easily in the following order H-F > H-OH > H-NH₂. In THF solvent the insertion reactions get more difficult than in gas phase.     

Synthesis and mass spectrometry characterization of centrally and terminally amine‐functionalized polyisobutylenes

This article reports the facile synthesis of novel terminally and centrally functionalized polyisobutylenes (PIBs) and the detailed characterization of the products by various mass spectrometry techniques. Specifically, H? PIB? CH₂? C(OH)CH₃? CH₂? NHCH₃ and [H? PIB? CH₂? CH(OH)CH₃? CH₂]₂? NCH₃ were synthesized by the quantitative epoxidation of H? PIB? CH₂? C(CH₃)?CH₂ and the subsequent conversion of the resulting epoxide with excess CH₃NH₂. Quaternization with CH₃Cl of these mixtures of secondary and tertiary amines yielded exclusively H? PIB? CH₂? C(OCH₃)CH₃? CH₂? N(CH₃)₂ from the secondary amine, whereas the tertiary (centrally functionalized) amine remained unchanged. Tandem mass spectrometry experiments provided unique insight into the precise connectivity of the functional end groups added to the PIB frame. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 946–958, 2005     

Gas transport properties of polyarylates part II: Tetrabromination of the bisphenol

The gas transport properties of a series of polyarylates based on isophthalic acid have been examined. The polyarylates were synthesized from the following bisphenol monomers with and without tetrabromo substitution: bisphenol A, hexafluorobisphenol A, phenolphthalein, and fluorene bisphenol, to study the effects of tetrabromination in combination with varying the bisphenol connector group size and shape. Substitution of a tertiary butyl group at position five on the isophthalate ring was used to increase polymer permeability. Tetrabromination of the bisphenol maintains or increases gas permeability and significantly increases permselectivity particularly for the O₂/N₂ gas pair as compared with the non-brominated analog. The substitution of t-butyl groups increases gas permeability by two-to fourfold but lowers permselectivity. Most of the increase in permeability can be related to an increase in the diffusion coefficient for each gas. All the brominated polyarylates have gas transport properties superior to most known glassy materials for O₂/N₂ separation with several materials close to a proposed empirical “upper bound” between permeability and selectivity. © 1995 John Wiley & Sons, Inc.     

Gitterschwingungsspektren. LXXI. Wasserstoffbrückenbindungen und synergetischer Effekt in kristallinen Amiden am Beispiel von NaAl(NH2)4

Lattice Vibration Spectra. LXXI Hydrogen Bonding and Synergetic Effect in Solid Amides: a Case Study for NaAl(NH₂)₄ IR and Raman spectra (4000 - 200 cm^?1, 90 K and 300 K) of NaAl(NH₂)₄ and of deuterated samples are recorded and discussed with respect to the bonding of NH₂^? ions in condensed phases compared to that of H₂O molecules and OH^?-ions. The bands observed are assigned to the internal vibrations and librations of the NH₂^? ions and skeleton vibrations of the distorted tetrahedral Al(NH₂)₄^? units (breathing vibration v₁, 572 cm^?1). Owing to the high charge density of the Al³⁺ ions the NH-stretching modes are shifted to higher wavenumbers by as many as 200 cm^?1 compared to those of free amide ions. Furthermore the H-bond donor strenght of the NH₂^? ions is so much enlarged (synergetic effect) that weak, unusally long (d( …? N) > 360 pm) NH₂ …? NH₂ hydrogen bonds are formed. These H-bonds share layers of vertex connected Al(NH₂)₄ and Na(NH₂)₄ tetrahedra within the structure.     

Darstellung und Struktur eines Ammoniumdiamidodioxophosphats(V), NH4PO2(NH2)2

Synthesis and Structure of an Ammonium Diamidodioxophosphate(V), NH₄PO₂(NH₂)₂ The ammonolysis of P₃N₅ under ammonothermal conditions (T = 400°C, p(NH₃) = 6 kbar, 14 d in autoclaves) in the presence of small definite amounts of water leads to the formation of NH₄PO₂(NH₂)₂. The structure was solved by single crystal X-ray methods. NH₄PO₂(NH₂)₂: P2₁/c (Nr. 14), a = 6.886(1) Å, b = 8.366(2) Å, c = 9.151(2) Å, β = 111.78(3)°, Z = 4, R₁/wR₂ = 0.026/0.072, Z(F > 2σ(F)) = 1183, N(variables) = 87. In NH₄PO₂(NH₂)₂ the anions [PO₂(NH₂)₂]^? are linked to chains by N? H …? N and N? H …? O bridge bonds. The ammonium ions are located between these chains and are donors for N? H …? O bridge bonds which connect the chains three-dimensionally.     

Surface characterization of plasma‐modified poly(ethylene terephthalate) film surfaces

Poly(ethylene terephthalate) (PET) film surfaces were modified by argon (Ar), oxygen (O₂), hydrogen (H₂), nitrogen (N₂), and ammonia (NH₃) plasmas, and the plasma‐modified PET surfaces were investigated with scanning probe microscopy, contact‐angle measurements, and X‐ray photoelectron spectroscopy to characterize the surfaces. The exposure of the PET film surfaces to the plasmas led to the etching process on the surfaces and to changes in the topography of the surfaces. The etching rate and surface roughness were closely related to what kind of plasma was used and how high the radio frequency (RF) power was that was input into the plasmas. The etching rate was in the order of O₂ plasma > H₂ plasma > N₂ plasma > Ar plasma > NH₃ plasma, and the surface roughness was in the order of NH₃ plasma > N₂ plasma > H₂ plasma > Ar plasma > O₂ plasma. Heavy etching reactions did not always lead to large increases in the surface roughness. The plasmas also led to changes in the surface properties of the PET surfaces from hydrophobic to hydrophilic; and the contact angle of water on the surfaces decreased. Modification reactions occurring on the PET surfaces depended on what plasma had been used for the modification. The O₂, Ar, H₂, and N₂ plasmas modified mainly CH₂ or phenyl rings rather than ester groups in the PET polymer chains to form C? O groups. On the other hand, the NH₃ plasma modified ester groups to form C? O groups. Aging effects of the plasma‐modified PET film surfaces continued as long as 15 days after the modification was finished. The aging effects were related to the movement of C?O groups in ester residues toward the topmost layer and to the movement of C? O groups away from the topmost layer. Such movement of the C?O groups could occur within at least 3 nm from the surface. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 3727–3740, 2004     

An ab initio molecular orbital study of the deprotonation of amines

The geometries of the amines NH₂X and amido anions NHX^?, where X = H, CH₃, NH₂, OH, F, C₂H, CHO, and CN have been optimized using ab initio molecular orbital calculations with a 4-31G basis set. The profiles to rotation about the N? X bonds in CH₃NH^?, NH₂NH^?, and HONH^? are very similar to those for the isoprotic and isoelectronic neutral compounds CH₃OH, NH₂OH, and HOOH. The amines with unsaturated bonds adjacent to the nitrogen atoms undergo considerable skeletal rearrangement on deprotonation such that most of the negative charge of the anion is on the substituent. The computed order of acidity for the amines NH₂X is X = CN > HCO > F ≈ C₂H > OH > NH₂ > CH₃ > H and for the reaction NHX^? + H⁺ → NH₂X the computed energies vary over the range 373–438 kcal/mol.     

Polysulfonylamine. LVII. Zwei Silber(I)-di(organosulfonyl)-amide mit einer Silber-η2-Aryl- beziehungsweise einer Silber-Silber-Wechselwirkung: Kristallstrukturen von Silberdi(benzolsulfonyl)-amid-Wasser (1/0,5) und von wasserfreiem Silberdi(4-toluolsulfonyl)-amid

Polysulfonyl Amines. LVII. Two Silver(I) Di(organosulfonyl)-amides with Silver-η²-Aryl or Silver-Silver Interactions: Crystal Structures of Silver Di(benzenesulfonyl)amide-Water (1/0.5) and of Anhydrous Silver Di(4-toluenesulfonyl)-amide Crystals of [(PhSO₂)₂NAg(μ-H₂O)AgN(SO₂Ph)₂]_n ( 5 ) and [(4-Me? C₆H₄SO₂)₂NAgAgN(SO₂C₆H₄-4-Me)₂]_n ( 6 ) were obtained from aqueous solutions. The crystallographic data are for 5 (at ?95°C): monoclinic, space group C2/c, a = 2 743.8(5), b = 600.49(12), c = 1 664.5(3) pm, β = 101.143(15)°, V = 2.6908 nm³, Z = 8, D_x = 2.040 Mg m^?3; for 6 (at ?130°C): monoclinic, space group P2₁/n, a = 1 099.8(5), b = 563.7(3), c = 2 487.7(13) pm, β = 99.68(4)°, V = 1.5203 nm³, Z = 4, D_x = 1.888 Mg m^?3. In both crystals, the silver atom has a fivefold coordination. The structure of 5 displays [(RSO₂)₂N? Ag(μ-H₂O)Ag′? N(SO₂R)₂] units with Ag? N 226.9 pm, Ag? O 236.7 pm and Ag? O? Ag′ 95.3°; the water oxygen lies on a crystallographic twofold axis. These units are extended to two fused six-membered rings by intramolecular dative bonds (S)O → Ag′ and S(O)′ → Ag (249.3 pm). One phenyl group from each (PhSO₂)₂N moiety is η²-coordinated with its p-C and one m-C atom to a silver atom of a neighbouring bicyclic unit related by a glide plane to form infinite parallel strands (p-C? Ag 252.2, m-C? Ag 263.9 pm). The strands are interconnected into parallel layers through hydrogen bonds between H₂O and sulfonyl oxygens [O …? O(S) 276.1 pm]. These layers consist of a hydrophilic inner region containing metal ions, N(SO₂)₂ fragments and water molecules, and hydrophobic surfaces formed by phenyl groups. The structure of 6 features centrosymmetric [(RSO₂)₂N? Ag? Ag′? N(SO₂R)₂] units with two intramolecular dative bonds (S)O → Ag′ and (S)O′ → Ag (Ag? Ag′ 295.4, Ag? N 226.0, Ag? O 229.4 pm). These bi-pentacyclic units are associated by translation parallel to y into infinite strands by two dative (S)O → Ag bonds per silver atom (Ag? O 243.2 and 253.3 pm).     

Preparation and emission properties of various poly(dimethylsilylenearylenevinylene)s: Effects of geometric structures and π units on their emission properties

trans‐Poly(dimethylsilylenearylenevinylene)s (trans‐rich) and cis‐poly(dimethylsilylenearylenevinylene)s (cis‐rich) containing phenylene, biphenylene, and phenylenesilylenephenylene units were prepared by hydrosilylation catalyzed with the RhI(PPh₃)₃ complex. The addition of a phenylene π unit to poly(silylenephenylenevinylene) expanded the conjugation in the main chain, whereas the insertion of a dimethylsilylene σ unit in the biphenylene moiety reduced the conjugation. UV spectra of the trans‐type polymers showed redshifts and hyperchromic effects with respect to those of the cis‐type polymers, indicating wider conjugation, and the quantum yields of emission of the former polymers were much higher than those of the latter polymers. The quantum yield of the trans‐rich polymer with the biphenylene moiety reached 0.15, which was about 10² times as large as those of trans‐type polymers with phenylene (3.4 × 10^?3) and phenylenesilylenephenylene (1.9 × 10^?3) moieties. The effects of the geometric structure and π unit on the absorption and emission properties of these polymers were examined with molecular orbital methods. © 2002 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 40: 535–543, 2002; DOI 10.1002/pola.10139     

Synthesis of norbornenes containing cationic mono‐ and di(cyclopentadienyliron)arene complexes and their ring‐opening metathesis polymerization

A number of classes of polynorbornenes containing cationic iron moieties within their side chains were prepared via ring‐opening metathesis polymerization with a ruthenium‐based catalyst. The iron‐containing polymers displayed excellent solubility in polar organic solvents. The weight‐average molecular weights of these polymeric materials were estimated to be in the range of 18,000–48,000. Thermogravimetric analysis of these polymers showed two distinct weight losses. The first weight loss was in the range of 204–260 °C and was due to the loss of the metallic moieties, whereas the second weight loss was observed at 368–512 °C and was due to the degradation of the polymer backbone. Cyclic voltammetry studies of the iron‐containing polymers showed that the 18 e^? cationic iron centers underwent a reduction to give the neutral 19 e^? complexes at half‐wave potential (E_1/2) = ?1.105 V. Photolysis of the metallated polymers led to the isolation of the norbornene polymers in very good yields. Differential scanning calorimetry studies showed a sharp increase in the glass‐transition temperatures up to 91 °C when rigid aromatic side chains were incorporated into the norbornene polymers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 3053–3070, 2006     

Homoleptic lanthanide guanidinate complexes: The effective initiators for the polymerization of trimethylene carbonate and its copolymerization with ε‐caprolactone

The ring‐opening polymerization of trimethylene carbonate (TMC) using homoleptic lanthanide guanidinate complexes [RNC(NR′₂)NR]₃Ln as single component initiators has been fully investigated for the first time. The substituents on guanidinate ligands and center metals show great effect on the catalytic activities of these complexes, that is, ? N(CH₂)₅ > ? NⁱPr₂ > ? NPh₂ (for R′), ? Cy > ? ⁱPr (for R), and Yb > Sm > Nd. Among them, [Ph₂NC(NCy)₂]₃Yb shows the highest catalytic activity. Some features and kinetic behaviors of the TMC polymerization initiated by [Ph₂NC(NCy)₂]₃Yb were studied in detail. The polymerization rate is first order, with the monomer concentration and M_n of the polymer increasing with the polymer yield increasing linearly. The results indicated the present system having “living character.” A mechanism that the polymerization occurs via acyl‐oxygen bond cleavage rather than alkyl‐oxygen bond cleavage was proposed. The copolymerization of TMC with ?‐caprolactone (ε‐CL) initiated by [Ph₂NC(NCy)₂]₃Yb was also tested. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1778–1786, 2005