Fluoride Ion Induced Reactions of Silicon−Oxygen and Silicon−Sulfur Bonds with Hexafluorocyclotriphosphazenes:  Synthesis, Reactivity, and X-ray Structural Analyses of Sulfur/Oxygen-Containing Monospirofluorophosphazenes^,

Abstract

Bifunctional trimethylsilyl ethers/thioethers/dithioethers react readily with N3P3F6 in the presence of a catalytic amount of CsF in THF to yield spirofluorophosphazenes or dangling or bridged fluorophosphazenes with concomitant elimination of Me3SiF. With sulfur-containing aliphatic bifunctional reagents of the type Me3SiX(CH2) n SSiMe3, five- and six-membered monospirofluorophosphazenes, N3P3F4[X(CH2) n S] [X = O or S; n = 2 or 3] (1−4), are formed in good yield. Crystals of N3P3F4[OCH2CH2S] (1) are monoclinic, P21/c; fw = 287.05, a = 8.727(10) Å, b = 11.246(2) Å, c = 9.787(2) Å, β = 100.91(10)°, V = 943.2(3) Å3, and Z = 4. N3P3P4[OCH2CH2CH2S] (2) is orthorhombic, Pbca; fw = 301.08, a = 12.399(4) Å, b = 10.105(2) Å, c = 16.787(2) Å, V = 2103.3(9) Å3, Z = 8. N3P3F4[SCH2CH2S] (3) is triclinic, P1̄; fw = 303.11, a = 9.501(2) Å, b = 9.764(3) Å, c = 11.092(5) Å, α = 74.97°, β = 88.03°, γ = 85.85°, V = 991.0(6) Å3, and Z = 2. N3P3F4[SCH2CH2CH2S] (4) is orthorhombic, Fdd2; fw = 317.14, a = 18.238(4) Å, b = 41.390(8) Å, c = 5.965(12) Å, V = 4503(2) Å3, and Z = 16. The 31P NMR spectra of these derivatives show a large dependence on the ring size and an attempt is made to explain this observation on the basis of structural parameters. Reactions of N3P3F6 with disiloxanes such as (Me3SiOCH2CH2)2O at temperatures below 80 °C yield only the dangling product 5a. When the reaction temperature is elevated to ∼110 °C, an oily liquid that is identified as the bridged fluorophosphazene (N3P3F5OCH2CH2)2O (5b) is isolated. When [Me3SiOC(CF3)2]2C6F4 acts as a bifunctional reagent, a totally fluorinated bridged phosphazene, [N3P3F5OC(CF3)2]2C6F4 (6), forms at ∼65 °C. Aromatic disiloxanes are very facile reagents for the formation of spirocyclic products when N3P3F6 is reacted under mild conditions with the bis(trimethylsilyl) ethers of 1,2-catechol, 3-fluoro-1,2-catechol, 2,3-naphthalenediol, and 2,2‘-biphenol. No ring degradation is observed with 3-F-1,2-C6H3(OSiMe3)2 and 1,2-C6H4(OSiMe3)2, which give the monospiro derivatives N3P3F4[3-F-1,2-C6H4O2] (7) and N3P3F4[1,2-C6H4O2] (8a) in good yields as well as the dispirophosphazene derivative N3P3F2[1,2-C6H4O2]2 (8b). Crystals of 8a are orthorhombic Imma; fw = 319.03, a = 7.4642(5) Å, b = 9.5108(7) Å, c = 16.2807(12) Å, V = 1155.78(14) Å3, and Z = 4; 8b is monoclinic, P21/n; fw = 389.12, a = 10.015(10) Å, b = 5.612(10) Å; c = 27.818(4) Å, β = 96.70°, V = 1552.8(4) Å3, Z = 4. N3P3F4[2,3-C10H6O2] (9a) is monoclinic, P21/c; fw = 369.09, a = 11.291(2) Å, b = 17.139(3) Å, c = 7.183(10) Å, β = 101.68°, V = 1361.2(4) Å3, Z = 4; N3P3F4[2,2‘-C12H8O2] (10) is monoclinic C2/c; fw = 395.12, a = 24.932(5) Å, b = 7.930(10) Å; c = 18.875(4) Å, β = 124.55°, V = 3073.6(10) Å3, Z = 8. The residual fluorine atoms on the phosphazene rings in 7, 8a, 9a, and 10 can be substituted by fluorophenoxy groups on reaction with the corresponding o-, m-, or p-(trimethylsilyl)phenoxy ether to give fully substituted phosphazenes of the type N3P3X(OC6H4F)4 [X = 3-F-1,2-C6H3O2 (11), 1,2-C6H4O2 (12), 2,3-C10H6O2 (13−15)...

Monospiroaryloxyphosphazenes: p-Fluorophenoxy Derivatives Containing the 1,2-Phenylenedioxy and 2,3-Naphthalenedioxy Groups

“…For compound (1), the mean planes of the fluoroaryloxy and N3P3 rings make dihedral angles of 90.0(1) for C7-C12 and 1~1.5 (1) ° for C13-C18 (bonded to P2), and 104.3 (1) for C19-C24 and 63.0 (1) ° for C25-C30 (bonded to P3). These values are greater than those found in N3P3(2,2'-O2CI2H8)(p-FC6H4)4 (Vij, Geib, Kirchmeier & Shreeve, 1996) owing to the presence of the less sterically demanding (vis-d-vis 2,2'-biphenoxy) 1,2-phenylenedioxy group. The conformations of the fluoroaryloxy rings on P2 and P3 are seen from the torsion angles C7--O3--P2--O4 -175.1 (2), C 13~Od P2---O3 -172.2 (2), C19--O5--P3--O6 -177.5 (2) and C25---O6--P3--O5 70.0 (2) °.…”

“…The base peak corresponds to the (M-OC6H4F) ÷ fragment. The multinuclear NMR spectral data are described elsewhere (Vij, Geib, Kirchmeier & Shreeve, 1996).…”

“…A synthetic methodology involving 1,2-bis-(trimethylsilyl)benzenediol and excess N3P3F6 affords the first examples of structurally characterized fluorocyclophosphazenes, i.e. monospiro N3P3F4(1,2-O2C6H4) (3), dispiro N3P3Fa(1,2-O2C6H4)2 (4) and monospiro N3P3F4(2,3-O2CIoH6) (5) (Vij, Geib, Kirchmeier & Shreeve, 1996). We present here the structure determinations of 4,4,6,6-tetrakis(4-fluorophenoxy)-2,2-(1,2-phenylenedioxy)-1,3,5,2,4,6-cyclophosphazene, ( 1 ), and 4,4,6,6-tetrakis(4-fluorophenoxy)-2,2-( 1,2-naphthalenedioxy)-1,3,5,2,4,6-cyclophosphazene, (2).…”

Chemistry of diphenyltetrafluorophosphazene: Reactions with dilithiated diols

“…3b) from planarity in comparison to N 3 P 3 F 6 ( Fig. 3a) [19,20]. It has been reported that one of the phosphorus atoms that is bearing the phenyl groups in the phosphazene ring of the gem-diphenyl tetrafluorophosphazene was deviated to a distance of 0.20 Å from the plane defined by the other five atoms of the phosphazene ring (Fig.…”

Chiral configurations in cyclophosphazene chemistry

“…The crystal structures of a number of mono-BP derivatives are given in below (164a [34e], 164b and c [191], 164d [192], 165 [193], 166 [34e], 167a and b [194], 167c and 168 [195], 169a-d [136]). Except for the crystal structures 168 [195] where the racemic configurational properties were stated as RS (or SR), none of the other structures of mono-spiro BP derivatives recorded that the molecule was racemic.…”