New stable monomeric germanium(II) and tin(II) compounds M(OCH 2 CH 2 NMe 2 ) 2 (M ) Ge (1); M ) Sn (2)), stabilized by two intramolecular coordination MrN bonds and containing no bulky groups on the metal atoms, were synthesized. The molecular and crystal structures of these compounds, and that of the previously synthesized compound (ArO) 2 Sn (3; Ar ) 2,4,6-(Me 2 NCH 2 ) 3 C 6 H 2 ), were determined by X-ray diffraction analysis. The electronic structures of 1 and 2 were studied by the DFT method.

The microstructure of poly(1,3‐pentadiene) synthesized by cationic polymerization of 1,3‐pentadiene with tBuCl/TiCl4 initiating system is analyzed using one‐dimensional‐ and two‐dimensional‐NMR spectroscopy. It is shown that unsaturated part of chain contains only homo and mixed dyads with trans−1,4‐, trans−1,2‐, and cis−1,2‐structures with regular and inverse (head‐to‐head or tail‐to‐tail) enchainment, whereas cis−1,4‐ and 3,4‐units are totally absent. The new quantitative method for the calculation of content of different structural units in poly(1,3‐pentadiene)s based on the comparison of methyl region of 13C NMR spectra of original and hydrogenated polymer is proposed. The signals of tert‐butyl head and chloromethyl end groups are identified in a structure of poly(1,3‐pentadiene) chain and the new approaches for the quantitative calculation of number‐average functionality at the α‐ and ω‐end are proposed. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 3297–3307

The microstructure of polybutadiene synthesized via cationic polymerization using TiCl4‐based initiating systems has been investigated using 1D (1Н, 2Н, and 13С) and 2D (HSQC and HMBC) NMR spectroscopy. It was found that trans‐1,4‐unit is predominant structure of unsaturated part of polymer chain. Besides, the small amount of 1,2‐structures was also detected, while cis‐1,4‐units were totally absent. The signals of carbon atoms of three types of head groups (trans‐1,4‐, 1,2‐, and tert‐butyl) and two types of end groups (trans‐1,4‐Cl and 1,2‐Cl) were identified for the first time in macromolecules of cationic polybutadiene. It was showed that tert‐butyl head groups were formed due to the presence in monomer of admixtures of isobutylene. The new methodology for calculation of the content of different structural units in polybutadiene chain as well as the head and end groups was proposed. It was established that main part of 1,2‐units distributed randomly along the polybutadiene chain as separate units between trans‐1,4‐structures. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 387–398

The microstructure of polyisoprene synthesized with t BuCl/TiCl 4 initiating system is investigated using 1D and 2D (HSQC and HMBC) NMR spectroscopy. It is found that trans-1,4-units with regular (head-to-tail) and inverse (tail-totail) and (head-to-head) enchainments are predominant structures of unsaturated part of polymer chain, while 1,2-and 3,4-units are presented in minor amounts. The new methodology for the quantitative calculation of the content of different structural units in polyisoprene chain including both types of inverse trans-1,4-addition (tail-to-tail and head-to-head) is proposed. It is shown that head groups consist of tert-butyl group connected to trans-1,4-unit of polyisoprene chain. In addition, two types of chlorine-containing end groups are found (trans-4,1-Cl and 4,3-Cl), while conjugated double bonds at the chain end are totally absent. The methodology for the calculation of number-average functionality by tertbutyl head and chlorine end groups, respectively, is developed.

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New stable divalent tin derivatives containing no bulky substituents at the metal atom, Hal-Sn-OCH 2 CH 2 NMe 2 (Hal = Cl or F), were synthesized, and their crystal structures were studied by X ray diffraction. Unlike the analogous monomeric divalent germanium de rivative Cl-Ge-OCH 2 CH 2 NMe 2 , the new compounds are centrosymmetric dimers formed via two intermolecular Sn←O coordination bonds.Earlier, 2 we have demonstrated that bidentate β di methylaminoethoxy ligands stabilize the divalent germa nium and tin compounds M(OCH 2 CH 2 NMe 2 ) 2 (M = Ge (1) or Sn (2)) in the monomeric form without steric shielding of the reactive center M by the bulky substitu ents. In the case of the germanium(II) derivatives, the presence of only one Me 2 NCH 2 CH 2 O ligand is sufficient for stabilization of the monomeric unsymmetrical com pounds XGeOCH 2 CH 2 NMe 2 (X = Cl (3) or OAc (4)). 3 In the present study, we synthesized new stable divalent tin derivatives Hal-Sn-OCH 2 CH 2 NMe 2 (Hal = Cl (5) or F (6)) analogous to the previously studied germa nium(II) derivative 3 and established their structures by X ray diffraction. Results and DiscussionDivalent tin chloro and fluoroalkoxides ClSnOCH 2 CH 2 NMe 2 (5) and FSnOCH 2 CH 2 NMe 2 (6) were prepared according to a known procedure for the synthesis of tin(II) alkoxyhalides containing no intramo lecular coordination bonds, 4-7 i.e., by the reactions of equimolar amounts of Sn(OCH 2 CH 2 NMe 2 ) 2 (2) and tin dihalides in THF at ~20 °C (Scheme 1).Compounds 5 and 6 are colorless crystalline substances unstable in the presence of even trace amounts of atmo spheric oxygen and moisture and soluble in polar aprotic organic solvents. The compositions of these compounds were determined by elemental analysis and confirmed by NMR spectroscopy.The structures of compounds 5 and 6 were studied by X ray diffraction. Unfortunately, crystals of fluoro de rivative 6 were of poor quality and, consequently, the experimental data did not allow us to discuss its structure in detail. However, the principal structure of this com pound was unambiguously established, and it is similar to that of chloroalkoxide 5. Hence, we comprehensively dis cuss only the structure of compound 5.We found that, unlike monomeric germa nium(II) alkoxychloride 3, tin(II) derivatives 5 and 6, like [N 3 SnOCH 2 CH 2 NMe 2 ] 2 (7) 8 and [(Me 3 Si) 2 NSnOCH 2 CH 2 NMe 2 ] 2 (8), 1 are centrosymmet * For Part 6, see Ref. 1. Scheme 1Hal = Cl (5), F (6)

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A new method for the identification of the structure of terminal units in poly(1,3‐pentadiene) synthesized by cationic mechanism is developed. The conducting of NMR experiments with a T2 filter allows the intensities of the spectral signals of carbon and hydrogen atoms of main chain groups of poly(1,3‐pentadiene) with a short relaxation time to be decreased and significantly increases the intensities of signals of carbon and hydrogen atoms of head and end groups, which are characterized by higher mobility. Using 1D NMR spectroscopy with a T2 filter as well as 2D heteronuclear single‐quantum correlation and heteronuclear multiple‐bond correlation NMR spectroscopy, it is found that the position of four out of five carbon atoms of the head group fully coincides with the position of spectral signals of carbon atoms of trans‐1,2‐ and trans‐1,4‐ units of a main polymer chain. This new method allows the identification of the signals of all carbon atoms in head trans‐1,4‐ group of poly(1,3‐pentadiene).