SYNTHESIS, STRUCTURE AND REACTIVITY OF BIS(N-ARYL-IMINOPHOSPHORANYL)METHANES - X-RAY CRYSTAL-STRUCTURES OF (4-CH3-C6H4-N=PPH2)2CH2 AND (4-NO2-C6H4-N=PME2)2CH2

The synthesis of novel bis(N-aryl-iminophosphoranyl)methanes of the type CH2(PR2=N-Ar)2 has been accomplished by reaction of methylene-bisphosphines with arylazides. These compounds have been fully characterized by 1H, 31P and l3C NMR, IR spectroscopy. Field Desorption Mass Spectroscopy (= FDMS) and elemental analysis. Variable temperature NMR experiments and single crystal X-ray structure determinations of CH2(PPh2=N-C6H4-CH2-4)2 (la) and CH2(PMe2 = N - C6H4-NO2-4)2 (If) reveal that bis(N-aryl-iminophosphoranyl)methane occurs as tautomer 1. Crystals of la are orthorhombic, space group Pcab, with a = 26. 602(2), 6 = 20.521(1), c= 11. 8859(7) Å and V = 6488. 5(7) Å3 (Z = 8, R = 0. 045 and Rw = 0. 066). The crystals of If are monoclinic, space group C/2c, with a = 20. 153(4), b = 5. 952(1), c = 16.930(5) Å, β = 106.24(3)° and V = 1949. 6(6) Å3 (Z = 4, molecular symmetry C2, R = 0. 051 and Rw = 0. 079). Both molecules consist of 2 iminophosphoranyl units bridged by a methylene group. The P=N bond distances of 1.568(2) and 1.566(2) Å for la and 1.580(4) Å for If represent normal values for iminophosphoranyl compounds. The N-C bond lengths of 1.386(2) and 1.390(2) Å (la) or 1.372(5) Å for If indicate that some electron delocalisation over the N-aryl moiety takes place. In la the electron delocalisation takes place separately in each iminophosphoranyl entity, while in If electron delocalisation occurs only in the N-aryl-NO2 moiety. Compound la is easily deprotonated using lithium-diisopropylamide or NaH and shows typical iminophosphoranyl chemistry, since with C02 an aza-Wittig reaction has been found and with HX (X=C1, Br) protonation of both imide nitrogen atoms has been observed. © 1990 Gordon and Breach Science Publishers, Inc. © 1990, Taylor & Francis Group, LLC. All rights reserved.