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Key Words: 1,3,5-Triaza-7-phospha-adamantane / Reductive cleavage of phosphonium salts t Ambidentate P,N-ligands t P,N-[3.3.l]bicyclononane systems t Phosphanes Two reaction pathways for the synthesis of 1,3,5-triaza-?-phosphoniaadamantane salts, RP[(CH2)6N3]+X-(l), were followed. Route 1 starts with commercial tetrakis(hydroxymethy1)phosphonium chloride, which is converted into P(CH,OH), by treatment with a base. Subsequent quaternization with alkyl halides RX and cyclization with formaldehyde and ammonia afford [R-TPA]+X-. This process is only applicable for R = Me (la) and Et (lb), however. Route 2 is more general and starts with primary phosphanes RPH,, which are converted into organotris(hydroxymethy1)phosphonium salts with formaldehyde and hydrochloric acid followed by ring closure with CH20/NH3 to give compounds l c -l f (R = t-Bu, c-Hex, Bz, and Ph, respectively, and X = C1, I, PFs, or BPh4). Reductive cleavage of compounds 1 by sodium in liquid ammonia proceeds with either external (P-R) or internal (P-CH2) bond rupture. P-R cleavage affords the 1,3,5-triaza-?-phosphaadamantane (TPA), while cage cleavage leads to new bowl-or helmet-shaped ligand systems with peripheral amine and phosphane functions (2). Yields of the cage-opening reaction are highest for R = Ph (2f), moderate for R = Me and Et (2a, 2b), and poor with the remaining R groups (2c-2e). A radical mechanism is proposed for this reaction, the leaving group properties of R determining the direction of the cleavage. The crystal and molecular structures of compounds 2a and 2f were determined by X-ray diffraction studies. Ex0 positions were found for the N-Me and P-R groups. The isomers with the R group in the endo position are also present in solution in small amounts, as detected by NMR spectroscopy. Isomer interconversion by P inversion is slow on the NMR time scale. Compounds 2a, 2b and 2f were oxidized with elemental sulfur and selenium to give the monosulfides and selenides, respectively (2aS, 2aSe, 2 bS, 2bSe, 2fS, 2fSe Tertiary phosphanes R3P are versatile ligands in coordination chemistry. Indroduction of functional groups in their organic substituents R can be used as a method to modify the properties of the ligands and of the complexes derived therefrom. The phosphanes can, for example, become (P,N)-ambi-or polydentate in nature, as tertiary amine functions become part of the organic framework [']. Owing to the hydrophilic nature of these amine functions, such ligands and their complexes will become soluble in water and other polar solvents.An example in case is 1,3,5-triaza-7-phospha-adamantane (TPA)L2], which is known to be a suitable "soft" P-donor for low-valent transition with a small cone angle at the phosphorus atom, but also a "hard" ligand for metals in higher oxidation stated4]. It can be integrated into hydrogen-bonding networks based on its three tertiary amine functions, and it is easily solvated. The molecule is a strong nucleophile and forms both phosphonium and ammonium cations if treated with acids or alkyl hali d e~ [~]...

Pseudopotential ab initio calculations on SAu3+ and S(AuPH&+ closely reproduce the experimental Au-S-Au angles of monomeric S(AuPR3)3+ (PR3 = PPh3, PPri3) if both correlation and relativistic effects are included.

The prolonged photo-Arbuzov reaction (3 weeks, Hg lamp) of 1,3,5-trichloro-benzene with a large excess of trimethyl phosphite (as a solvent) at 508 gives moderate yields of dimethyl (3,5-dichlorophenyl)phosphonate (1; 14.5%), tetramethyl (5-chloro-1,3-phenylene)bis[phosphonate] (2; 35.4%), and hexamethyl (benzene-1,3,5-triyl)tris[phosphonate] (3; 30.1%). The products can be separated by fractional distillation. Acid hydrolysis of the esters gives almost quantitative yields of the corresponding phosphonic acids 4 ± 6. Reduction of the esters 1 ± 3 by LiAlH 4 in tetrahydrofuran affords the primary phosphines (3,5-dichlorophenyl)phosphine (7; 46.5%), (5-chloro-1,3-phenylene)bis[phosphine] (8; 34.5%) and (benzene-1,3,5-triyl)tris[phosphine] (9; 25.2% yield). In the crude reduction products from 2 (preparation of 8) and from 3 (preparation of 9), (3-chlorophenyl)phosphine and (1,3-phenylene)bis[phosphine], respectively, are observed as by-products. All compounds are characterized by standard analytical, spectroscopic, and (for 1, 7, and 8) structural techniques. The arrangement of the molecules in the crystal structures of 7 and 8 suggest that H-bonding between the primary arylphosphines is virtually insignificant for the packing of the components. This is in marked contrast to the importance of H-bonding for the supramolecular chemistry of arylamines. The new primary polyphosphines and polyphosphonic acids are to be employed in the construction of extended arrays.Introduction. ± Arylphosphines play an important role in many areas of contemporary chemistry. Tertiary phosphines Ar 3 P are the most prominent class of ligands for transition metals, and their complexes are used as homogeneous catalysts in a large variety of reactions [1]. They are also the base chemicals for many reagents in organic synthesis including phosphonium salts [2], phosphonium ylides [2 ± 4], phosphine boranes [2] [5], and phosphine oxides and sulfides [2]. Secondary phosphines Ar 2 PH are less common in catalysts and also as reagents, but their PÀH group offers an additional functionality for the design of more sophisticated substitution patterns and for oxidation products. Finally, primary phosphines ArPH 2 are the least developed series of arylphosphines with still very limited areas of application [6 ± 8]. However, their potential as synthons is even greater owing to two reactive PÀH functions in addition to the nucleophilic/donor center at the P-atom.Only a relatively small number of primary arylphosphines has been prepared and fully characterized [9 ± 11], and this is particularly true for aromatic hydrocarbons with more than one primary phosphine function [6] [12 ± 23]. For benzene itself, the complete set of primary phosphines has the general formula C 6 H n (PH 2 ) 6Àn comprising a total of 12 species, of which only less than half are known (Fig. 1).Current interest in advanced materials with tailored structures and properties has attracted increasing attention to polyphosphinoarenes with a rigid skeleton, on which new structural motifs...

Reductive cleavage of the methylphosphoniatriazaadamantane cation by sodium in liquid ammonia affords the new bicyclic ligand (MeP)(CH2)5N2(NMe) whose structure has been determined from crystals of its 1 : 1 complex with AuCI.