New Hybrid Polyurea-Polyurethane Elastomers with Antistatic Properties and an Influence of Various Additives on Their Physicochemical Properties.

Polyurea is a synthetic high-strength elastomeric material that can be sprayed as a coating over existing structures in order to protect against weathering effects. It is ideal for anti-corrosion protection and is characterized by excellent mechanical properties and adhesion to various surfaces. Further development of this technology may allow obtaining new coatings with improved antistatic properties, which would be an excellent alternative compared to used antistatic epoxy paints. This paper will examine the influence of tetraalkylammonium salt (1), potassium hexafluorophosphate solution (2) and imidazolium-based ionic liquid (3) on the improvement of antistatic properties of the polyurea-polyurethane coatings. In addition, the modified samples were also verified in terms of changes in mechanical properties and the appearance of functional groups other than in the reference sample, as well as surface defects that may arise due to incompatibility of the antistatic additive with the polymer matrix. In order to obtain information about the properties mentioned above, the electrical resistance was determined, the tensile strength and elongation were measured, FT-IR spectra were made, and images were taken with the use of scanning electron microscopy. The conducted research showed that the antistatic properties of the tested hybrid coatings could be improved, but their use may be associated with certain limitations that should be taken into account when designing such materials.

Flame Retardancy Properties and Physicochemical Characteristics of Polyurea-Based Coatings Containing Flame Retardants Based on Aluminum Hydroxide, Resorcinol Bis(Diphenyl Phosphate), and Tris Chloropropyl Phosphate.

Polyurea is a synthetic material made by the reaction of isocyanate and polymer blend-containing amines. Due to its outstanding mechanical properties and fast curing, polyurea-based coatings have found dozens of applications, including waterproofing and anti-corrosion coatings. Further development of this material can create a flame-retardant product, a good alternative for common products available on the market, such as intumescent coatings. To improve the flame retardancy of polyurea, several flame retardants were investigated. The influence of aluminum hydroxide, resorcinol bis(diphenyl phosphate) (RDP), and tris chloropropyl phosphate (TCPP) on flame retardancy and morphology was studied. The following methods were used: infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, limiting oxygen index, and tensile strength. The examinations mentioned above showed the improvement of flame-retardancy of polyurea for two products: chlorinated organophosphate and organophosphate. Nevertheless, using the chlorinated organophosphate additive caused a rapid deterioration of mechanical properties.

Cationic P-S-X cages (X=Br, I).

The first condensed-phase preparation of ternary P-Ch-X cations (Ch=O-Te, X=F-I) is reported: [P5S3X2]+, [P5S2X2]+, and [P4S4X]+ (X=Br, I). [P5S3X2]+ is formed from the reaction of the Ag+/PX3 reagent with P4S3. The [P5S3X2]+ ions have a structure that is related to P4S5 by replacing P=S by P+--X and S in the four-membered ring by P(X). We provide evidence that the active ingredient of the Ag+/PX3 reagent is the (H2CCl2)Ag-X-PX2+ cation. The latter likely reacts with the HOMO of P4S3 in a concerted HOMO-LUMO addition to give the P5S3X2+ ion as the first species visible in situ in the low-temperature 31P NMR spectrum. The [P5S3X2]+ ions are metastable at -78 degrees C and disproportionate at slightly higher temperatures to give [P5S2X2]+ and [P4S4X]+, probably with the extrusion of 1/n (PX)n (X=Br, I). All six new cage compounds have been characterized by multinuclear NMR spectroscopy and, in part, by IR or Raman spectroscopy. The [P5S2X2]+ salts have a nortricyclane skeleton and were also characterized by X-ray crystallography. The structure of the [P4S4X]+ ion is related to that of P4S5 in that the exo-cage P=S bond is replaced by an isoelectronic P+--X moiety.

Silver complexes of cyclic hexachlorotriphosphazene.

The first solid-state structures of complexed P3N3X6 (X = halogen) are reported for X = Cl. The compounds were obtained from P3N3Cl6 and Ag[Al(OR)4] salts in CH2Cl2/CS2 solution. The very weakly coordinating anion with R = C(CF3)3 led to the salt Ag(P3N3Cl6)2+[Al(OR)4]- (1), but the more strongly coordinating anion with R' = C(CH3)(CF3)2 gave the molecular adduct (P3N3Cl6)AgAl(OR')4 (3). Crystals of [Ag(CH2Cl2)(P3N3Cl6)2]+[Al(OR)4]- (2), in which Ag+ is coordinated by two phosphazene and one CH2Cl2 ligands, were isolated from CH2Cl2 solution. The three compounds were characterized by their X-ray structures, and 1 and 3 also by NMR and vibrational spectroscopy. Solution and solid-state 31P NMR investigations in combination with quantum chemically calculated chemical shifts show that the 31P NMR shifts of free and silver-coordinated P3N3Cl6 differ by less than 3 ppm and indicate a very weakly bound P3N3Cl6 ligand in 1. The experimental silver ion affinity (SIA) of the phosphazene ligand was derived from the solid-state structure of 3. The SIA shows that (PNCl2)3 is only a slightly stronger Lewis base than P4 and CH2Cl2, while other ligands such as S8, P4S3, toluene, and 1,2-Cl2C2H4 are far stronger ligands towards the silver cation. The energetics of the complexes were assessed with inclusion of entropic, thermal, and solvation contributions (MP2/TZVPP, COSMO). The formation of the cations in 1, 2, and 3 was calculated to be exergonic by delta(r)G(degrees)(CH2Cl2) = -97, -107, and -27 kJ mol(-1), respectively. All prepared complexes are thermally stable; formation of P3N3Cl5+ and AgCl was not observed, even at 60 degrees C in an ultrasonic bath. Therefore, the formation of P3N3Cl5+ was investigated by quantum chemical calculations. Other possible reaction pathways that could lead to the successful preparation of P3N3X5+ salts were defined.

A spirocyclic P-S cage cation: synthesis and formation of P7S6I2+.

Upon ionization of the P4S3I2 molecule with Ag[Al(OR)4], a highly reactive sulfonium cation P4S3I+ is generated (NMR simulated and assigned). At -80 degrees C this cation reacts with additional P4S3I2 to give either an iodophosphonium P4S3I3+ cation (NMR simulated and assigned) and P4S3 or to give several isomers of a metastable compound that is probably P8S3I3+. This mixture decomposes at 0 degrees C to give only three isomers of the spirocyclic P7S6I2+ cage cation (31P NMR simulated and assigned, X-ray of one isomer, IR assigned). The oxidation of the [Ag(P4S3)2]+ complex by I2 also resulted in the formation of P7S6I2+, but with more by-products. The spirocyclic 15-atom cage of P7S6I2+ has no precedent and contains the first phosphonium center bonded only to P and S atoms. This structural element gives the first experimental clue as to how formal charge-bearing elements in the still unknown class of binary P-Ch (Ch = chalcogen) or homopolyatomic P cations may be constructed.

Lewis acid stabilized OPI3: implications for the nature of free OPI3.

While reinvestigating the published synthesis of OPI(3), it became evident from the experiments that phosphoryl triodide may only be formed as an intermediate and that the end products of the reaction of OPCl(3) with LiI are P(V) oxides, PI(3), I(2), and LiCl. This is also in agreement with MP2/TZVPP calculations, which assign Delta(r)H degrees (Delta(r)G degrees ) [Delta(r)G degrees in CHCl(3)] for the disproportionation of OPI(3) as -7 (-18) [-17 kJ mol(-1)] (assuming P(4)O(10) as the P(V) oxide). The first products of this reaction visible in a low-temperature in situ (31)P NMR experiment are P(2)I(4) and PI(3), as well as traces of a compound that may be OPCl(2)I. By contrast, it was possible to prepare and structurally characterize Lewis acid [A] stabilized [A]<--OPX(3) adducts, where [A] is Al(OR(F))(3) for X=Br and Al(OR(F))(2)(mu-F)Al(OR(F))(3) for X=I (R(F)=C(CF(3))(3)). These adducts are formed on decomposition of PX(4) (+)[Al(OR(F))(4)](-); high yields of Br(3)PO-->Al(OR(F))(3) (delta((31)P)=-65) were obtained, while I(3)PO-->Al(OR(F))(3) (delta((31)P)=-337) and I(3)PO-->Al(OR(F))(2)(mu-F)Al(OR(F))(3) (delta((31)P)=-332) are only formed as by-products. The main product of the room-temperature decomposition of PI(4) (+)[Al(OR(F))(4)](-) is PI(4) (+)[(R(F)O)(3)Al(mu-F)Al(OR(F))(3)](-), which was also characterized by X-ray crystallography and was independently prepared from Ag(+)[(R(F)O)(3)Al(mu-F)Al(OR(F))(3)](-), PI(3), and I(2).

Preparation of stable AsBr4+ and I2As-PI3+ salts. Why didn't we succeed to prepare AsI4+ and As2X5+? A combined experimental and theoretical study.

In analogy to our successful "PX2+" insertion reactions, an "AsX2+" insertion route was explored to obtain new arsenic halogen cations. Two new salts were prepared: AsBr4+[Al(OR)4]-, starting from AsBr3, Br2 and Ag[Al(OR)4], and I2As-PI3+[Al(OR)]4 from AsI3, PI3 and Ag[Al(OR)4](R=C(CF3)3). The first cation is formally a product of an "AsBr2+" insertion into the Br2 molecule and the latter clearly a "PI2+" insertion into the As-I bond of the AsI3 molecule. Both compounds were characterized by IR and NMR spectroscopy, the first also by its X-ray structure. Reactions of Ag[Al(OR)4] with AsI3 do not lead to ionization and AgI formation but rather lead to a marginally stable Ag(AsI3)2+[Al(OR)]4 salt. Despite many attempts we failed to prepare other PX-cation analogues such as AsI4+, As2X5+ and P4AsX2+(X=Br, I). To explain these negative results the thermodynamics of the formation of EX2+, EX4+ and E2X5+(E = As, P; X = Br, I) was carefully analyzed with MP2/TZVPP calculations and inclusion of entropy and solvation effects. We show that As2Br5+ is in very rapid equilibrium with AsBr2+ and AsBr3(DeltaGo((CH2Cl2))=+30 kJ mol(-1)). The extremely reactive AsBr2+ cation available in the equilibrium accounts for the observed decomposition of the [Al(OR)4]- anion. By contrast, the stability of AsI3 against Ag[Al(OR)4] appears to be kinetic and, if prepared by a suitable route, As2I5+ would be expected to have a stability intermediate between the known P2I5+ and P2Br5+.

A theoretical study on the formation of EX4+ and E2X5+(E = P, As; X = Br, I) from Ag+ and EX3/X2.

The mechanism and the thermodynamics of the formation of EX2+, EX4+ and E2X5+ (E = As, P; X = Br, I) was carefully analyzed with MP2/TZVPP calculations and inclusion of entropy and solvation effects (COSMO model approximating CH2Cl2). Thus, as likely intermediates the complexes of Ag+ and one or two EX3 as well as EX3/X2 were optimized. The global minimum isomers of the Ag(EX3)2+ intermediates were found to be P-coordinated Ag(PI3)2+ and (BrPBr2)Ag(PBr3)+ but exclusively halogen coordinated Ag(X2AsX)2+ complexes. Similarly complicated is the situation for the Ag(EX3)(X2)+ intermediates: (I3E)Ag(I2)+, (BrAsBr2)Ag(Br2)+ and (Br3P)(Br-Br)Ag+ complexes were found to be the global minima. Based on all available results likely mechanisms for the formation of the known PX4+, AsBr4+, P2X5+ salts (X = Br, I) from these intermediates were proposed. An explanation for the failure to prepare an AsI4+ salt is also given.

Oxidation of CS4 by AsBr4+: the unexpected formation of the simple CS2Br3+ carbenium ion.

During the preparation of AsBr4(+)[Al(OR)4]-, the novel carbocation CS2Br3+ was synthesized by reaction of AsBr3, Br2, CS2, and Ag[Al(OR)4] (R=C(CF3)3). CS2Br3(+)[Al(OR)4]- was characterized by its crystal structure, NMR and IR spectroscopy, and quantum chemical calculations (including COSMO solvation enthalpies). Additional experiments as well as the computed thermodynamics indicated two likely reaction pathways: Ag(+) +2Br2 +CS2-->CS2Br3(+) +AgBr and the direct 4e- oxidation reaction AsBr4(+) +CS2-->CS2Br3(+) + 1/6As6Br6. Both reactions were observed experimentally and were calculated to be exergonic in solution by -226 and -56 kJ mol(-1) respectively. As a result of charge delocalization the C-S and C-Br distances in the cation are shortened by 0.06 to 0.08 A; the S--Br distances are also slightly shortened indicating a delocalization of the charge also to the bromine atoms in the (S--Br moieties. Based on an analysis of the cation-anion contacts as well as quantum chemical MP2 calculations, a delocalization model as a planar 10 pi electron system is discussed and the pi molecular orbitals are given. It will be shown that the electronic situation of CS2Br3+ is very close to that in CBr3+, that is, the properties of SBr moieties and Br atoms as pi donors towards a formal C+ center are comparable.

Extending the coordination chemistry of molecular P(4)S(3): the polymeric Ag(P(4)S(3))(+) and Ag(P(4)S(3))(2)(+) cations.

Upon reacting P(4)S(3) with AgAl(hfip)(4) and AgAl(pftb)(4) [hfip = OC(H)(CF(3))(2); pftb = OC(CF(3))(3)], the compounds Ag(P(4)S(3))Al(hfip)(4) 1 and Ag(P(4)S(3))(2)(+)[Al(pftb)(4)](-) 2 formed in CS(2) (1) or CS(2)/CH(2)Cl(2) (2) solution. Compounds 1 and 2 were characterized by single-crystal X-ray structure determinations, Raman and solution NMR spectroscopy, and elemental analyses. One-dimensional chains of [Ag(P(4)S(3))(x)](infinity) (x = 1, 1; x = 2, 2) formed in the solid state with P(4)S(3) ligands that bridge through a 1,3-P,S, a 2,4-P,S, or a 3,4-P,P eta(1) coordination to the silver ions. Compound 2 with the least basic anion contains the first homoleptic metal(P(4)S(3)) complex. Compounds 1 and 2 also include the long sought sulfur coordination of P(4)S(3). Raman spectra of 1 and 2 were assigned on the basis of DFT calculations of related species. The influence of the silver coordination on the geometry of the P(4)S(3) cage is discussed, additionally aided by DFT calculations. Consequences for the frequently observed degradation of the cage are suggested. An experimental silver ion affinity scale based on the solid-state structures of several weak Lewis acid base adducts of type (L)AgAl(hfip)(4) is given. The affinity of the ligand L to the silver ion increases according to P(4) < CH(2)Cl(2) < P(4)S(3) < S(8) < 1,2-C(2)H(4)Cl(2) < toluene.

From weakly coordinating to non-coordinating anions? A simple preparation of the silver salt of the least coordinating anion and its application to determine the ground state structure of the Ag(eta2-P4)2+ cation.

The unexpected but facile preparation of the silver salt of the least coordinating [(RO)3Al-F-Al(OR)3]- anion (R=C(CF3)3) by reaction of Ag[Al(OR)4] with one equivalent of PCl3 is described. The mechanism of the formation of Ag[(RO)3Al-F-Al(OR)3] is explained based on the available experimental data as well as on quantum chemical calculations with the inclusion of entropy and COSMO solvation enthalpies. The crystal structures of (RO)3Al<--OC4H8, Cs+[(RO)2(Me)Al-F-Al(Me)(OR)2]-, Ag(CH2Cl2)3+[(RO)3Al-F-Al(OR)3]- and Ag(eta2-P4)2+[(RO)3Al-F-Al(OR)3]- are described. From the collected data it will be shown that the [(RO)3Al-F-Al(OR)3]- anion is the least coordinating anion currently known. With respect to the fluoride ion affinity of two parent Lewis acids Al(OR)3 of 685 kJ mol(-1), the ligand affinity (441 kJ mol(-1)), the proton and copper decomposition reactions (-983 and -297 kJ mol(-1)) as well as HOMO level and HOMO-LUMO gap and in comparison with [Sb4F21]-, [Sb(OTeF5)6]-, [Al(OR)4]- as well as [B(R(F))4]- (R(F)=CF3 or C6F5) the [(RO)3Al-F-Al(OR)3]- anion is among the best weakly coordinating anions (WCAs) according to each value. In contrast to most of the other cited anions, the [(RO)3Al-F-Al(OR)3] anion is available by a simple preparation in conventional inorganic laboratories. The least coordinating character of this anion was employed to clarify the question of the ground state geometry of the Ag(eta2-P4)2+ cation (D(2h), D(2) or D(2d)?). In agreement with computational data and NMR spectra it could be shown that the rotation along the Ag-(P-P-centroid) vector has no barrier and that the structure adopted in the solid state depends on packing effects which lead to an almost D(2h) symmetric Ag(eta2-P4)2+ cation (0 to 10.6 degrees torsion) for the more symmetrical [Al(OR)4]- anion, but to a D2 symmetric Ag(eta2-P4)2+ cation with a 44 degrees twist angle of the two AgP2 planes for the less symmetrical [(RO)3Al-F-Al(OR)3]- anion. This implies that silver back bonding, suggested by quantum chemical population analyses to be of importance, is only weak.

PX4+, P2X5+, and P5X2+ (X=Br, I) salts of the superweak Al(OR)4- anion [R=C(CF3)3].

PX(4) (+)[Al(OR)(4)](-) (X=I: 1 a, X=Br: 1 b) was prepared from X(2), PX(3), and Ag[Al(OR)(4)] [R=C(CF(3))(3)] in CH(2)Cl(2) at -30 degrees C in 69-86 % yield. P(2)X(5) (+) salts were prepared from 2 PX(3) and Ag[Al(OR)(4)] in CH(2)Cl(2) at -30 degrees C yielding almost quantitatively P(2)X(5) (+)[Al(OR)(4)](-) (X=I: 3 a, X=Br: 3 b). The phosphorus-rich P(5)X(2) (+) salts arose from the reaction of cold (-78 degrees C) mixtures of PX(3), P(4), and Ag[Al(OR)(4)] giving P(5)X(2) (+)[Al(OR)(4)](-) (X=I: 4 a, X=Br: 4 b) with a C(2v)-symmetric P(5) cage. Silver salt metathesis presumably generated unstable PX(2) (+) cations from PX(3) and Ag[Al(OR)(4)] (X=Br, I) that acted as electrophilic carbene analogues and inserted into the Xbond;X (Pbond;X/Pbond;P) bond of X(2) (PX(3)/P(4)) leading to the highly electrophilic and CH(2)Cl(2)-soluble PX(4) (+) (P(2)X(5) (+)/P(5)X(2) (+)) salts. Reactions that aimed to synthesize P(2)I(3) (+) from P(2)I(4) and Ag[Al(OR)(4)] instead led to anion decomposition and the formation of P(2)I(5)(CS(2))(+)[(RO)(3)Al-F-Al(OR)(3)](-) (5). All salts were characterized by variable-temperature solution NMR studies (3 b also by (31)P MAS NMR), Raman and/or IR spectroscopy as well as X-ray crystallography (with the exception of 4 a). The thermochemical volumes of the Pbond;X cations are 121 (PBr(4) (+)), 161 (PI(4) (+)), 194 (P(2)Br(5) (+)), 271 (P(2)I(5) (+)), and 180 A(3) (P(5)Br(2) (+)). The observed reactions were fully accounted for by thermochemical calculations based on (RI-)MP2/TZVPP ab initio results and COSMO solvation enthalpy calculations (CH(2)Cl(2) solution). The enthalpies of formation of the gaseous Pbond;X cations were derived as +764 (PI(4) (+)), +617 (PBr(4) (+)), +749 (P(2)I(5) (+)), +579 (P(2)Br(5) (+)), +762 (P(5)I(2) (+)), and +705 kJ mol(-1) (P(5)Br(2) (+)). The insertion of the intermediately prepared carbene analogue PX(2) (+) cations into the respective bonds were calculated, at the (RI-)MP2/TZVPP level, to be exergonic at 298 K in CH(2)Cl(2) by Delta(r)G(CH(2)Cl(2))=-133.5 (PI(4) (+)), -183.9 (PBr(4) (+)), -106.5 (P(2)I(5) (+)), -81.5 (P(2)Br(5) (+)), -113.2 (P(5)I(2) (+)), and -114.5 kJ mol(-1) (P(5)Br(2) (+)).