4-Substituierte 1,3 ,5,7-Tetramethyl-1,3,5,7-tetraaza-4λ 5 -phosphaspiro-[3.3]heptan-2,6-dione; Röntgenstrukturanalyse von 1,3,4,6,7,9,10-Heptamethyl-5-oxa-1,3 ,7,9,10-pentaaza-4 λ 5 ,6 λ 5 -diphosphadispiro[3.1.3.1]decan-2,8-dion / 4-Substituted 1,3,5,7-Tetramethyl- 1,3,5,7-tetraaza-4λ 5 -phosphaspiro[3.3]heptane-2,6-diones; Crystal Structure of 1,3,4,6,7,9,10-Heptamethyl-5-oxa-1,3,7,9,10-pentaaza-4λ 5 ,6λ 5 -diphosphadispiro[3.1.3.1]decane-2,8-dione

The reaction of the tetrachlorophosphoranes RPCl 4 (R=Me, Ph) with N,N′-dimethylurea (dmh) (1), or of the diazaphosphetidinone O=C(NMe) 2 PR (R=CCl 3 ) (3) and chlorine with N,N′-bis(trimethylsilyl)-N,N′-dimethylurea (2) furnished the spiro compounds RP[(NMe) 2 C=O] 2 (7-9). The dichlorophosphoranes O=C(NMe) 2 PRCl 2 (4-6) are intermediates in these reactions; 4 and 6 were isolated but 5 could not be obtained pure. In the reaction of 4 with 2 a mixture of products was formed, from which the novel tricyclic diphosphorane 1,3,4,6,7,9,10-heptamethyl-5-oxa-1,3,7,9,10-pentaaza-4 λ 5 ,6 λ 5 -diphosphadispiro-[3.1.3.1]decane-2,8-dione (10) was isolated in low yield. Its identity and structure were established by 1 H, 13 C and 31 P NMR spectroscopy and by a single crystal X-ray structure determination, which confirmed the presence of the novel oxazadiphosphetidine ring. 10 crystallizes in C2/c with a = 1321.1(3), b = 687.6(1), c = 1674.5(3) pm, β= 103.30(2)° and Z = 4; R = 0.039 for 1437 unique observed reflections. A crystallographic twofold axis passes through the Me-N···O moiety of the central ring