Synthese und Eigenschaften der 1,3-Benzazaphosphole

Synthesis and Properties of the 1,3-Benzazaphospholes 1H-1,3-Benzazaphospholes (R = H, CH₃, C₆H₅, N(CH₃)₂) are synthesized not only rom o-aminophenylphosphines and different cyclisation compounds such as R? C(OR)?NH · HCl, R? C(O)Cl, R? COOR′, R? C(OCH₃)₂NR′₂, or Cl₂C?N(CH₃)₂Cl but also from secondary o-aminophenylphosphines PRH? C₆H₄? NH₂ (R = C₆H₅, C₂H₅) and CH₃? C(OR)?NH · HCl under elimination of ether or from 1,3-benzazaphospholines after oxidation or thermal treatment. Whereas the 1,3-benzazaphospholes don't react with acetyl chloride or methyl iodide the N-acetyl- and P-methyl-1,3-benzazaphospholes are formed starting with the ambident anion. Further reactions of the 1,3-benzazaphospholes and the nmr data of the compounds prepared are discussed.      

Proton-assisted addition reactions on trimethylsilylalkynyl nitrosylrutheniums of hydrotris(pyrazolyl)borate

Incorporation of H₂O or HCl on treatment of trimethylsilylalkynyl nitrosylruthenium TpRuCl(CCSiMe₃)(NO) (1) (Tp = hydrotris(pyrazolyl)borate) with protic acid, and the dependence of its product formation on the reaction solvents, are reported. Reactions of 1 with HBF₄ or HCl (aq.) in MeOH gave rise to the mixture of the mono(ethynyl) TpRuCl(CCH)(NO) (2) and the mono(acyl) TpRuCl{C(O)CH₃}(NO) (3). The H₂O-incorporated 3 was quantitatively obtained from the reactions of 2 with HCl (aq.) in MeOH. On the other hand, reactions of 1 with HCl (aq.) in CH₂Cl₂ gave the η¹-α-chlorovinyl TpRuCl{C(Cl)CH₂}(NO) (4). In the bis(alkynyl) system TpRu(CCSiMe₃)₂(NO) (5), the similar reactivities were observed. Proton-assisted hydration of 5 afforded the bis(acyl) TpRu{C(O)CH₃}₂(NO) (6), while the HCl-treatment led to the formation of the bis(α-chlorovinyl) TpRu{C(Cl)CH₂}₂(NO) (7).     

Mechanism and characterization of alkylene‐ and p‐ethylenebenzylene‐spaced polycarbosilanes ceramic precursor synthesized by electropolymerization

An electropolymerization of haloalkylhalosilanes (Cl? R? SiCH₃Cl₂) that possess two types of electroactive sites, that is, the C? Cl and Si? Cl bond is described. The one‐pot synthesis method is shown to yield branched polycarbosilanes having a regular carbon block‐spaced silicon backbone structure. A series of branched polycarbosilanes, [? R? SiCH₃? ]_n with R being ? CH₂? , ? C₂H₄? , ? C₃H₆? , and ? CH₂? C₆H₄? C₂H₄? , have been successfully electropolymerized with M_n up to 42,600 Dalton. Experimental and simulation cyclic voltammetry of these monomers and the computational examination of their LUMOs are applied to study the electropolymerization mechanism. The results suggest that polymerization proceeds by iterating steps involving (1) electroreduction of a C? Cl bond to a carbanion, which is catalyzed by silylanion radical [Cl SiCl(CH₃)RCl] and/or Ni(0)/TDA‐1; and (2) nucleophilic attack of carbanions to Si? Cl bonds of a second monomer or oligomer to extend the polymer chain. The investigation reveals that the R spacer has a considerable impact on the polymerizability of the corresponding monomer. Such interfacial polymerization resembles a template polymerization, leading to unique microstructures that were preserved even after converted to silicon carbide ceramics at high temperatures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7677–7689, 2008     

Radical addition of alkylbenzenes to α,α-dichlorovinyl compounds

Conclusions Toluene and p-xylene react with ,-dichloroolefins CCl₂=CHCH₂R (R = Cl, OCH₃, CH₂CH₃, and CH₂-CH₂ Cl) with tert-butyl peroxide initiation, to form adducts predominantly with the structure HCCl₂CH(CH₂C₆H₄X)-CH₂ R (X =p–CH₃), which corresponds to the orientation of the addition of the benzyl radicals to the -carbon atom of the chloroolefin with the formation of the more stable radicals. The formation of compounds CCl₂ = CHCH(CH₂C₆H₅)CH₂CH₂Y (Y = H and Cl) was also noted.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 8, pp. 1809–1812, August, 1976.     

Structure and formation of gaseous [C4H5O]+ ions. IV—Ions derived from the cyclopropenium ion [C3H3]+

Characterization of [C₄H₅O]⁺ ions in the gas phase using their metastable ion and collisional activation spectra shows that the three isomeric ions HC?C? \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}H? OCH₃, CH₃O? \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}?C?CH₂ and ? OCH₃ related to the two stable [C₃H₃]⁺ cations [HC?C? CH₂]⁺ and are stable for ≥ 10^?5s. In contrast to the formation of cyclopropenium ions, it is found that the methoxy cyclopropenium ion is not generated from acyclic precursor molecules. The small but significant intensity differences found in the collisional activation spectra of [C₃H₃]⁺ ions generated from HC?C? CH₂I and HC?C? CH₂Cl possibly indicate the presence of [C₃H₃]⁺ ions of different structures.     

The Catalytic Oxidative Coupling of Methane

One of the great challenges in the field of heterogeneous catalysis is the conversion of methane to more useful chemicals and fuels. A chemical of particular importance is ethene, which can be obtained by the oxidative coupling of methane. In this reaction CH₄ is first oxidatively converted into C₂H₆, and then into C₂H₄. The fundamental aspects of the problem involve both a heterogeneous component, which includes the activation of CH₄ on a metal oxide surface, and a homogeneous gas-phase component, which includes free-radical chemistry. Ethane is produced mainly by the coupling of the surface-generated CH radicals in the gas phase. The yield of C₂H₄ and C₂H₆ is limited by secondary reactions of CH radicals with the surface and by the further oxidation of C₂H₄, both on the catalyst surface and in the gas phase. Currently, the best catalysts provide 20% CH₄ conversion with 80% combined C₂H₄ and C₂H₆ selectivity in a single pass through the reactor. Less is known about the nature of the active centers than about the reaction mechanism; however, reactive oxygen ions are apparently required for the activation of CH₄ on certain catalysts. There is spectroscopic evidence for surface O^? or O ions. In addition to the oxidative coupling of CH₄, cross-coupling reactions, such as between methane and toluene to produce styrene, have been investigated. Many of the same catalysts are effective, and the cross-coupling reaction also appears to involve surface-generated radicals. Although a technological process has not been developed, extensive research has resulted in a reasonable understanding of the elementary reactions that occur during the oxidative coupling of methane.     

Bildung siliciumorganischer Verbindungen. 85 [1]. Bildung,Reaktionen und Struktur des 1,1,3,3-Tetramethyl-2,4-bis(trimethylsilyl)-1,3-disilabicyclo[1, 1, 0]butans

me₃Si? CCl₂?Sime₂Cl (me ? CH₃) läßt sich mit n-buLi (bu ? C₄H₉) bei–100°C (Lösungsmittel THF/Äther) in me₃Si? CCl(Li)? Sime₂Cl a überführen. das mit meJ me₃Si? CClme? Sime₂Cl bildet. Wird a in Abwesenheit eines Abfangreagenzes langsam erwärmt, so bildet sich unter Abspaltung von LiCl (Cl aus der SiCl-Gruppe) über eine reaktive Zwischenstufe des Bicyclobutans b . Die Struktur von b ist durch NMR-Untersuchung, Röntgenstrukturanalyse und Abbaureaktionen gesichert. Mit HBr bzw. CH₃OH werden die Si? C-Bindungen der Dreiringe in b gespalten, so daß sich me₃Si? CH₂? C(Sime₂X)₂Sime₃ (X ? Br, OCH₃) bildet. Formation of Organosilicon Compounds. 85. Formation, Reactions, and Structure of 1,1,3,3-Tetramethyl-2,4-bis(trimethylsilyl)-1,3-disilabicyclo[1, 1, 0]butane me₃Si? CCl₂? Sime₂Cl (me ? CH₃) with n-buLi (bu ? C₄H₉) at –100°C (solvent: THF/ether) yields me₃Si? CCl(Li)? Sime₂Cl a , which forms me₃Si? CClme? Sime₂Cl with meI. By warming a slowly in absence of any trapping reagent the bicyclobutane b is obtained via a reactive intermediate under elimination of LiCl (Cl from the SiCl group). The structure of b is established by nmr investigations, X-ray structure determination and chemical derivatisation.     

Reactions of Cyclopalladated Benzylidene-aniline Schiff's Base Complexes. Selective Synthesis of 2′-Substituted Schiff's Base Derivatives and the X-Ray Crystal Structure of the Dimer [Pd(μ-OAc)(5′-OCH3?C6H3CHNC6H4-4-CH3)]2

The 2′-cyclopalladated imine complex , reacts with CO in MeOH to afford the 2′-substituted aryl imine 2′-CO₂CH₃-5′-OCH₃? C₆H₃CH?NTol (Tol = C₆H₄-4-CH₃). The product of this reaction can be altered by changing the bridging ligand from AcO to Cl, in which case only the 5-membered ring heterocyclic compound is obtained. [Pd(μ-OAc)( 1a )]₂ with 2 equiv. of Ph₃P and CO (1 atm) gives the heterocyclic which arises from two CO insertion reactions, whereas [PdX( 1a )]₂ (X = AcO, Cl) with 4 equiv. of C?NBu^t and 4 equiv. of Ph₂PCH₂CH₂PPh₂ affords the heterocyclic ketenimine [PdCl( 1a )]₂ reacts with CH₂?CHCO₂CH₂CH₃ to afford 2′(? CH?CHCO₂CH₂CH₃)-5′-OCH₃C₆H₃CHO, and [Pd(μ-OAc)( 1a )]₂ with I₂ to give 2′-I-5′-OCH₃C₆H₃CHO. Excess CH₃O₂CC?CCO₂CH₃ reacts with various substituted cyclopalladated Schiff's bases in MeOH to afford which we formulate as possessing two Pd? C bonds, and one coordinated ester O atom. The X-ray crystal structure of [Pd(μ-OAc)( 1a )]₂ has been determined; relevant bond lengths [Å] and bond angles [°] are: Pd? O(1), 2.139(6), Pd? O(2), 2.026(6), Pd? N, 2.039(6), Pd? C(2′), 1.951(8), Pd? Pd, 3.113(1), N? Pd? C(2′), 80.9(3), N? Pd? O(1), 97.5(2), C(2′)? Pd? O(2), 91.7(3), O(1)? Pd? O(2), 89.2(2).     

Kristallstrukturen der Fluorochloroplatinate(IV) cis-[(C5H5N)2CH2][PtF4Cl2], trans-[(C5H5N)2CH2][PtF4Cl2] · H2O und [(C5H5N)2CH2][PtF5Cl]

Crystal Structures of the Fluorochloroplatinates(IV) cis-[(C₅H₅N)₂CH₂][PtF₄Cl₂], trans-[(C₅H₅N)₂CH₂][PtF₄Cl₂] · H₂O, and [(C₅H₅N)₂CH₂][PtF₅Cl] The complex ions cis-[PtF₄Cl₂]^2?, trans-[PtF₄Cl₂]^2? and [PtF₅Cl]^2? have been synthesized by stereoselective ligand exchange reactions utilizing the trans effect and are separated by ion exchange chromatography on diethylaminoethyl cellulose. These anions form stable AB-type salts with the doubly charged cation dipyridiniomethane, [(C₅H₅N)₂CH₂]²⁺. X-ray structure determinations on single crystals of cis-[(C₅H₅N)₂CH₂][PtF₄Cl₂] ( 1 ) (monoclinic, space group P2₁/n with a = 10.379(10), b = 9.635(2), c = 13.738(2) Å, β = 99.142(10)°, Z = 4), trans-[(C₅H₅N)₂CH₂][PtF₄Cl₂] · H₂O ( 2 ) (triclinic, space group P1 with a = 7.757(4), b = 10.059(7), c = 10.408(6) Å, α = 82.49(5), β = 68.92(4), γ = 75.46(4)°, Z = 2) and [(C₅H₅N)₂CH₂][PtF₅Cl] ( 3 ) (orthorhombic, space group Pnma with a = 10.394(3), b = 13.320(2), c = 9.2694(10) Å, Z = 4), reveal the perfect ordering of the anion sublattice. The stronger trans influence of Cl compared with F is observed in asymmetric axes $ {\rm F}^ \bullet $? Pt? Cl′. The bond lengths Pt? $ {\rm F}^ \bullet $ are 0.026 Å (1.4%) longer and the Pt? Cl′ distances are 0.078 Å (3,3%) shorter in comparison with those of symmetrically coordinated axes. The weakening of the Pt? $ {\rm F}^ \bullet $ bond and the strengthening of the Pt? Cl′ bond is better recognizable from shifts of the stretching vibrations by 8% to lower and by 13% to higher frequencies, respectively. Correspondingly, the valence force constants are found to be 15% lower and 22% higher. The trans influence is observed most distinctly in the ¹⁹F-nmr spectra exhibiting the coupling constant ¹J($ {\rm F}^ \bullet $Pt) to be 29% smaller than ¹J(FPt).     

A spin-trap ESR study of the regrouping of radicals with 1,3 or 1,5 hydrogen migration

Conclusions Spin-trap (2-methyl-2-nitrosopropane) ESR methods have been used to demonstrate the formation of R¹O₂CR²CH₂CH₂C₆H₁₃ (R¹=H, CH₃ and R²=Cl, CH₃) radicals during the photoinitiated reaction ( 2537 Å) of 1-octene with BrCHClCOOH and CH₃CHBrCOOCH₃ in the presence of tert-outyl peroxide and (C₃H₅)₃SiH. Formation of these radicals indicates regrouping of the R¹O₂CCHR²CH₂HC₆H₁₃ radical with 1,3 H atom migraion and, possibly, regrouping of the R¹O₂CCHR²CH₂CH(C₆H₁₃)CH₂CHC₆H₁₃ radical with 1,5 H atom migration.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 3, pp. 545–549, March, 1977.     

Molecular Beam Mass Spectrometry System for Characterization of Thermal Plasma Chemical Vapor Deposition

A molecular beam mass spectrometry system for in situ measurement of the concentration of gas phase species including radicals impinging on a substrate during thermal plasma chemical vapor deposition (TPCVD) has been designed and constructed. Dynamically controlled substrate temperature was achieved using a variable thermal contact resistance method via a backside flow of an argon/helium mixture. A high quality molecular beam with beamtobackground signal greater than 20 was obtained under film growth conditions by sampling through a small nozzle (75 m) in the center of the substrate. Mass discrimination effects were accounted for in order to quantify the species measurements. We demonstrate that this system has a minimum detection limit of under 100 ppb. Quantitative measurements of hydrocarbon species (H, H₂, C, CH₃, CH₄, C₂H₂, C₂H₄) using Ar/H₂/CH₄ mixtures and silicon species (Si, SiH, SiH₂, SiCl, SiCl₂, Cl, HCl) using Ar/H₂/SiCl₄ mixtures were obtained under thermal plasma chemical vapor deposition conditions.     

Über die Reaktion von Schwefel mit Aminen und Formaldehyd. Eine neue Methode zur Herstellung von Thioformamiden und Dithiocarbamaten

The reaction of sulfur with primary or secondary amines and formaldehyde has been studied. A simple one step process for the preparation of thioformamides (RR′NCHS; R ? H, R′ ? CH₃, C₂H₅; R ? R′ ? CH₃, C₂H₅; R+R′ ? ? (CH₂), ? (CH₂), ? C₂H₄OC₂H) and the amine salts of N, N-dialkyl-dithiocarbamic acids (R₂NCS₂ · H₂NR₂, R ? CH₃, C₂H₅, C₄H₉; R₂ ? ? (CH₂), ? (CH₂), ? C₂H₄OC₂H) is reported. In addition, the isolation of diethylamidosulfoxylic acid, (C₂H₅)₂NSOH · 1/2 H₂O, the first derivative of a new class of compounds, is described. The physical properties and the ¹H-NMR. spectra of the above mentioned compounds are given.     

Structure and formation of gaseous [C4H5O]+ Ions. II–Ions of the type HCC?\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}(OH)(CH3)

Loss of an alkyl group X? from acetylenic alcohols HC?C? CX(OH)(CH₃) and gas phase protonation of HC?C? CO? CH₃ are both shown to yield stable HC?C? \documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}(OH)(CH₃) ions. Ions of this structure are unique among all other [C₄H₅O]⁺ isomers by having m/z 43 [C₂H₃O]⁺ as base peak in both the metastable ion and collisional activation spectra. It is concluded that the composite metastable peak for formation of m/z 43 corresponds to two distinct reaction profiles which lead to the same product ion, CH₃\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}?O, and neutral, HC?CH. It is further shown that the [C₄H₅O]⁺ ions from related alcohols (like HC?C? CH(OH)(CH₃)) which have an α-H atom available for isomerization into energy rich allenyl type molecular ions, consist of a second stable structure, H₂C?\documentclass{article}\pagestyle{empty}\begin{document}$ \mathop {\rm C}\limits^{\rm + } $\end{document}? C(OH)?CH₂.     

Beiträge zur Komplexchemie der Phosphine und Phosphinoxide,XXVIII. Übergangsmetall-aminoalkylphosphin-Komplexe Teil 2: Palladium- Und Platinkomplexe

On the Coordination Chemistry of Phosphines and Phosphine Oxides. XXVIII. Transition Metal Aminoalkylphosphine Complexes. Part II: Palladium and Platinum Complexes Aminoalkylphosphines – C₆H₅HP? CH₂ · CH₂? , (C₆H₅)₂P? CH₂ · CH₂ · CH₂? NH₂, (C₆H₅)₂P? CH₂ · CH₂ · CH₂? N?CHC₆H₅ – react with palladium and platinum salts to give coordination compounds of the type MX₂, MX₂()₂, and MX₂()₄ (M = Pd, Pt; X = Cl, BPh₄). The chelating activity of the ligands, structure and properties of the metal complexes are discussed.     

Intramolekulare C?H-Aktivierung bei der Reaktion von Bis(benzylcyclopentadienyl)zirconiumdichlorid mit Vinyllithium — Bildung eines Crotyl-zirconacyclus

Intramolecular C? H Activation at Reaction of Bis(benzylcyclopentadienyl)zirconium Dichloride with Vinyllithium — Formation of a Crotyl Zirconacyclus Bis(benzylcyclopentadienyl)zirconium dichloride, (C₆H₅CH₂? C₅H₄)₂ZrCl₂ ( V ), reacts with vinyl lithium with formation of the chiral compound (C₆H₅CH₂? C₅H₄)? ? CH₂CH=CHCH₃ ( IX ) as the product of vinyl group coupling and an orthometallation reaction. The reaction mechanism and the ¹³C n.m.r. spectrum are discussed.     

Formation of propylene in the reaction of methane with acetylene on a NiOx/BN heterogeneous catalyst

Reaction of methane with acetylene in the presence of a heterogeneous NiO_x/BN catalyst in the temperature range 300–450C results in the formation of propylene (1% yield). Using¹³CH₄ it was found that propylene arises both as a product of acetylene conversion and as a hydromethylation product of C₂H₂ with methane. The ratio of heavy and light C₃H₆ in the product mixture was 14.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2478–2481, November, 1990.     

Gas‐phase reactions of Cl atoms with propane,n‐butane,and isobutane

Using the relative kinetic method, rate coefficients have been determined for the gas‐phase reactions of chlorine atoms with propane, n‐butane, and isobutane at total pressure of 100 Torr and the temperature range of 295–469 K. The Cl₂ photolysis (λ = 420 nm) was used to generate Cl atoms in the presence of ethane as the reference compound. The experiments have been carried out using GC product analysis and the following rate constant expressions (in cm³ molecule^?1 s^?1) have been derived: (7.4 ± 0.2) × 10^?11 exp [‐(70 ± 11)/ T], Cl + C₃H₈ → HCl + CH₃CH₂CH₂; (5.1 ± 0.5) × 10^?11 exp [(104 ± 32)/ T], Cl + C₃H₈ → HCl + CH₃CHCH₃; (7.3 ± 0.2) × 10^?11 exp[?(68 ± 10)/ T], Cl + n‐C₄H₁₀ → HCl + CH₃ CH₂CH₂CH₂; (9.9 ± 2.2) × 10^?11 exp[(106 ± 75)/ T], Cl + n‐C₄H₁₀ → HCl + CH₃CH₂CHCH₃; (13.0 ± 1.8) × 10^?11 exp[?(104 ± 50)/ T], Cl + i‐C₄H₁₀ → HCl + CH₃CHCH₃CH₂; (2.9 ± 0.5) × 10^?11 exp[(155 ± 58)/ T], Cl + i‐C₄H₁₀ → HCl + CH₃CCH₃CH₃ (all error bars are ± 2σ precision). These studies provide a set of reaction rate constants allowing to determine the contribution of competing hydrogen abstractions from primary, secondary, or tertiary carbon atom in alkane molecule. © 2002 Wiley Periodicals, Inc. Int J Chem Kinet 34: 651–658, 2002     

Synthesis of novel tri-podal mesogenic alkenes and side-chain polysiloxanes

Low molecular weight tri-podal biphenyl- and benzoate-type mesogens [C₆H₅C₆H₄O(CH₂)₅SiMe₂CH₂CH₂SiMe₂]₃CH (4), [C₁₁H₂₃O(C₆H₄)₂O(CH₂)₅SiMe₂]₃CH (5) and [MeOC₆H₄OC(O)C₆H₄O(CH₂)₅SiMe₂]₃CH (6) (C₆H₄ = 1,4-phenylene) were obtained, from branched silyl substituted methane precursors [CH₂CH(Me)₂Si]₃CH (1) and (HMe₂Si)₃CH (2). The biphenyl-containing ones (4) and (5) were converted into terminal alkenes, which were subsequently hydrosilylated with poly(methylsiloxanes). The polymer derived from (5) exhibited mesomorphic properties. Such systems have the potential to significantly increase the density of liquid crystal rod-like structures in side chains of linear polymers (or dendritic liquid crystal polymers).     

Quasiliving Carbocationic Poiymerization. III. Quasiliving Polymerization of lsobutylene

The polymerization of isobutylene has been investigated by the use of the steady, slow, continuous monomer addition technique in the presence of a variety of initiating systems, i.e., “H₂O”/TiCl₄, “H₂O”/AlCl₃, C₆H₅C(CH₃)₂Cl/TiCl₄, p-ClCH₂ C₆(CH₃)₄* CH₂Cl/AlCl₃ at -50°C. Quasiliving polymerizations have been obtained with the “H₂O” and C₆H₅(CH₃)₂Cl/TiC1₄ systems in 60/40 v/v n-hexane/methylene chloride solvent mixtures with very slow monomer input. After a brief “flash” polymerization, the M _n of PIB increased linearly with the cumulative amount of monomer added (consumed); however, the number of polymer molecules formed also increased, indicating the presence of chain transfer to monomer. With the “H₂O”/TiCl₄ initiating system, M _n,max was 56,000 and M _w /M _n < 2.0. By the use of the C₆H₅C(CH₃)₂CL/TiCl₄ initiating system, quasiliving polymerization has been achieved and chain transfer could virtually be eliminated.     

α,ω-Disubstituted polymethylpolyphosphonates and polyphenylpolyphosphonates from condensation polymerization

Condensation polymerization of phosphonates through formation of P? O? P linkages has been achieved by (1) volatilization of methyl chloride from mixtures of CH₃P(O)Cl₂ with CH₃P(O)(OCH₃)₂; (2) volatilization or chemical removal of water from CH₃P(O)(OH)₂; and (3) volatilization of HCl from mixtures of CH₃P(O)Cl₂ with CH₃P(O)(OH)₂ or C₆H₅P(O)Cl₂ with C₆H₅P(O)(OH)₂. Depending on the proportions of the reagents, the polymerization products consist of various mixtures of chain molecules of the type \documentclass{article}\pagestyle{empty}\begin{document}${\rm X \hbox{--} P}({\rm O})({\rm R})\rlap{--}[{\rm O \hbox{--} P}({\rm O})({\rm R})\rlap{--}]_n {\rm X}$\end{document} for R = CH₃ and X = OCH₃, Cl, or OH, or for R = C₆H₅, x = Cl or OH. ³¹P nuclear magnetic resonance (NMR) was used to investigate both the polymethylpolyphosphonates and the polyphenylpolyphosphonates; and ¹H NMR of the CH₃P and CH₃O moieties was also used to study the polymethylpolyphosphonates. In the methoxyl-terminated polymethylpolyphosphonates, which was the system studied most extensively, no detectable amounts of cyclic molecules were found at equilibrium, but a crystalline methylphosphonic anhydride, CH₃PO₂, exhibited some ring structures. The equilibrium size distributions gave evidence that the sorting of the mono- and difunctional phosphorus-based units making up the oligomeric chains is affected by neighboring units. Kinetic measurements demonstrated that the condensation polymerization is a complicated process involving considerable scrambling of terminal groups with bridging oxygen atoms.