Chemistry of diazaphospholephosphines. 2. Exocyclic phosphine-sulfido, -selenido, and -imido derivatives of a diazaphospholephosphine system. Crystaland molecular structures of two diazaphospholephosphine imines: 4-(Difluoro((p-cyanotetrafluorophenyl)imino)phosphorano)-2,5-dimethyl-2H-1,2,3 sigma(2)-diazaphosphole and 4-(Bis(dimethylamino) (((pentamethylcyclopentadienyl)dichlorotitanio)imino)phosphorano)-2,5-dimethyl-2H-1,2,3 sigma(2)-diazaphosphole

The substituted-exo-phosphine (X = F, NMe2, OCH2CF3) diazaphospholephosphin es are exclusively oxidized at this center with either chalcogens (S, Se) o r azides to phosphoranodiazaphospholes. Oxidation imparts a dramatic upfiel d shift of the phosphorus NMR signals and an increase in the (1)J(PC) coupl ing constants within the ring. (Difluorophosphino)diazaphosphole was also o xidized with selected amines using diethyl azodicarboxylate (DAD) as the co upling agent. Bulky amines (e.g., 2,4,6-tri-tert-butylaniline (mes*)) gave the monomeric iminophosphorane whereas less bulky amines (p-toluidine) form ed mostly the cyclic diazadiphosphetidine. The crystal and molecular struct ure of 4-(difluoro((p-cyanotetrafluorophenyl)imio)-2,5-dimethyl-2H-1,2,3 si gma(2)-diazaphosphole was determined: triclinic, P (1) over bar (No. 2), a = 7.2744(15)Angstrom, b = 10.087(4) Angstrom, c 10.566(2) Angstrom, alpha = 66.62(2)degrees, beta = 77.60(2)degrees, gamma = 78.14(3)degrees, V - 688. 81:4) Angstrom(3), Z = 2. Final indices are R-1 = 0.0368 and wR(2) = 0.0968 , and for all data, R-1 = 0.0478, wR(2) = 0.1033, and GOF = 1.067. The stru cture revealed two planar ring systems consisting of the diazaphosphole and the p- tetrafluorophenyl (tfbn) ring with an angle of 26.3 degrees between the rings. The angle about the phosphine imine nitrogen (i.e., P=N-tfbn) i s relatively open (141.2(2)degrees) and the P=N bond length is relatively s hort (1.514(2) Angstrom). (((Trimethylsilyl)imino)(bis(dimethylamio))phosph orano)diazaphosphole gave, with Cp*TiC3, [(eta(5)-C5Me5)TiCl2(N=P(NMe2)(2)( 2,5-dimethyl-2H-1,2,3 sigma(2)-diazaphosphol-4-yl))], which was also charac terized structurally: monoclinic, P2(1) (No. 4), a = 11.9477(11) Angstrom, b = 8.4757(6) Angstrom, c = 12.7567(11) Angstrom, beta = 108.824(8)degrees V = 1222.7(2) Angstrom(3), Z = 2. Final indices are R1 = 0.0630 and wR(2) = 0.1593, and for all data, R1 = 0.0768, wR(2) = 0.1973, and GOF = 1.081. Th e Ti-N-P angle of 161.0(5)degrees was large, and the P=N distance (1.592(6) Angstrom and the Ti-N distance (1.781(6) Angstrom) were both slightly shor ter than those in similar titanium complexes. The P-N single bond distances between the exo-phosphorus atom and the attached dimethylamino groups were also short (1.649 Angstrom (average)). These short values suggest delocali zed bonding character throughout the metalligand framework, possibly a cons equence of additional conjugation through the diazaphosphole ring.