CLEFT REACTIVITY IN SKELETALLY-STABILIZED CYCLOTETRAPHOSPHAZANES

Molecular cleft selectivity and exo- vs endo-phosphorus site regiosele ctivity of cyclotetraphosphazanes [C6H4N2-(Phe)(2)](2) (1) and [C6H4N2 (PhP)(PhPS)](2) (2) have been examined. Oxidation of 1 with O-3 or Sg occurs regioselectively to form exo-phosphorus substituted [C6H4N2(PhP )(PhPO)](2) (4) and 2, respectively; Ag+ ion coordination and CH3I qua ternization occurs at exo sites with no apparent involvement of the cl eft (endo-) phosphorus atoms. Insertion of O atoms into the deft of 4 yields endo-substituted (C6H4N2)(2)(PhP)(PhPO)(3) (5) and [C6H4N2(PhPO )(2)](2) (6); insertion of S, AgNO3, or Ni(CO)(2) into the cleft of 2 yields (C6H4N2)(2)(PhP)(PhPS)(3) (10), [C6K4N2(PhPS)(2)](2) (11), {[C6 H4N2(PhP)(PhPS)](2) . Ag}NO3 (12), and [C6H4N2(PhP)(PhPS)]Ni-2(CO)(2) (15). Selenium oxidizing reagents (elemental Se and KCNSe), elemental Te, the larger metal moieties Mo(CO)(3) and Mo(CO)(4), and BH3 and CH3 I are excluded from reactivity in the cleft of 2. Complex 12 undergoes further reaction to form the mono- and dioxides (C6H4N2)(2)(PhP)(PhPO )(PhPS)(2) (13) and [C6H4N2(PhPO)(PhPS)](2) (14), via a process whereb y oxidation by novel Ag+ activation occurs. New compounds are characte rized by spectral data; structures of 4, 10, 11, and 15 were establish ed by single crystal X-ray analysis: 4, monoclinic, C2/c, a = 19.154(8 ) Angstrom, b = 9.081(4) Angstrom, c = 18.832(9) Angstrom, beta = 103. 09(4)degrees, Z = 4, V = 3190(2) Angstrom(3), d(obs) = 1.400 g/cm(3), R = 0.041, R(w) = 0.050; 10, triclinic, P (1) over bar, a = 11.209(2) Angstrom, b = 13.449(2) Angstrom, c = 13.872(3) Angstrom, alpha = 92.3 73(14)degrees, beta = 96.703(14)degrees, gamma = 105.718(14)degrees, Z = 2, V = 1993.4(6) Angstrom(3), d(obs) = 1.357 g/cm(3), R = 0.047, R( w) = 0.060; 11, monoclinic, C2/c, a = 26.674(5) Angstrom, b = 9.976(2) Angstrom, c = 19.732(5) Angstrom, beta = 120.47(1)degrees, Z = 4, V = 4525.5(17), d(obs) = 1.358 g/cm(3), R = 0.045, R(w) = 0.053; 15, mono clinic, C2/c, a = 28.583(13) Angstrom, b = 15.524(9) Angstrom, c = 18. 409(8) Angstrom, beta = 114.75(5)degrees, Z = 8, V = 7418(6) Angstrom( 3), d(obs) = 1.467 g/cm(3), R = 0.075, R(w) = 0.073. The basic cyclote traphosphazane structure characterized by 1 and 2 is maintained upon i nsertion into the molecular cleft of one S atom (10)or a Ni(CO)(2) moi ety (15); however, two S atoms in the cleft (11) causes severe distort ion of the ring system.