Poly(carbophosphazenes): a new class of inorganic-organic macromolecules

Chemistry of Boratophosphazenes: Synthesis of Borazine-Phosphazene Hybrid Cations, and New Inorganic Heterocycles by Skeletal Substitution Reactions

“…Molecular structure of 1 with thermal ellipsoids at the 30 % probability level. Selected bond lengths [] and angles [8]: B(1) ± N(1) 1.536 (6), N(1) ± P(1) 1.583(4), P(1) ± N(3) 1.551 (4), N(3) ± P(2) 1.544(4), P(2) ± N(2) 1.602 (4), N(2) ± B(1) 1.531(5), B(1) ± Cl(5) 1.847(5), B(1) ± Cl(6) 1.903 (4)…”

“…Remarkably, the two boron ± chlorine bonds differ significantly, with the B(1) ± Cl(5) bond lying approximately in the best plane of the NP 2 N 3 ring and 1.847(5) long, which is comparable to that found in cyclic chloroborane ± amine adducts such as the dimeric species (Cl 2 BNMe 2 ) 2 [1.830(10) ]. [23] In contrast, the B(1) ± Cl (6) bond is approximately perpendicular to the best plane of the six-membered ring and is markedly elongated to 1.903 (4) . Together with the significant shortening of the skeletal B ± N bonds, this elongation suggests that Cl(6) is close to heterolytic dissociation, which would generate a borazine-like planar environment at B(1).…”

“…The structures were consistent with the spectroscopic data, and confirmed that the chlorine atom attached to boron in 1 had successfully been abstracted to yield a boron ± nitrogen ± phosphorus cation with tetrachloroaluminate or -gallate as the counterion. No significant interactions between the cation and anion were observed, with the closest B´´Ć l (6) 4 ]. This indicates an increased degree of p bonding in the cations and, furthermore, the B ± N bond lengths are similar to those found in the borazines (1.43 ).…”

“…Evidence for the formation of a product involving amine coordination to the boron atom of [2] (8). The reaction of 1 with silver(i) salts containing even less coordinating anions (e.g., [AsF 6 ] À and [SbF 6 ] À ) resulted in the discovery of a new type of reaction for boron-containing heterocycles. Thus the As and Sb atoms were found to replace boron in a skeletal substitution reaction forming novel arsenic (v) .…”

Ring-Opening Polymerization—An Introductory Review

“…If one of the −PCl 2 -groups in the ring is exchanged for XCl (see Figure 67) the ring strain can be increased and a ring-opening polymerization occurs at lower temperature but necessity of subsequent substitution of the -Cl groups and the crosslinking during polymerization remain as disadvantages [190][191][192]. An alternative method to increase the ring strain is shown in Figure 68.…”