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Twenty 3,4,5-triaryl-1-R-1,2-diphospholes were studied within the framework of density functional theory (DFT) and experimentally by UV/vis spectroscopy to check their suitability for opto-electronic applications. Time-dependent DFT (TD-DFT) calculations employing the PBE0 hybrid density functional combined with moderately sized def-TZVP basis set were shown to excellently reproduce the experimental absorption spectra of various 1,2-diphospholes. Frontier molecular orbital analysis reveals that HOMO and LUMO are mainly localized on the diphosphole ring and, to some extent, on the aryl moieties. The HOMO-LUMO energy gap can be easily tuned by variation of substituents introduced in para-positions of the aryl moieties and, to a lesser extent, by modification of the R group at phosphorus atom. As a result, both position and intensity of the absorption bands with highest wavelength are strongly influenced by the above structural changes. The UV-spectra simulations reveal that the introduction of donor groups like para-OMe, para-NMe2, and para-N(H)Ph, which are in n-π conjugation with the aryl moieties, should result in absorption of visible light by the corresponding 1,2-diphospholes, thus making them promising candidates for new functional materials.

Reactions of sodium 3,4,5 triphenyl 1,2 diphosphacyclopentadienide with primary alkyl bromides, secondary alkyl iodides, and silicon and tin chlorides gave stable 1 substituted 1,2 diphospholes. In a solution of 3,4,5 triphenyl 1 trimethylstannyl 1,2 diphosphacyclopenta 2,4 diene, the Me 3 Sn group migrates between two phosphorus atoms.

Reactions of trisodium heptaphosphide with alkyl tosylates gave dialkylheptaphosphides or trialkylheptaphosphines, depending on the stoichiometric ratios of the starting reagents. A method for determination of the coupling constants of the asymmetric isomer of trialkyl heptaphosphines was proposed. Reactions of the heptaphosphide trianion with aryl tosylates yielded disodium hexadecaphosphide.Development of new methods for the synthesis of prac tically useful organophosphorus derivatives directly from white phosphorus is a topical problem in organophospho rus chemistry. 1 At the same time, the chemical properties of alkali metal polyphosphides, which are intermediates in the transformations of the elemental phosphorus mol ecule (in particular, the most accessible heptaphosphide trianion), have not been studied extensively in reactions with organic substrates. 2,3 It has been demonstrated 4-6 that trilithium heptaphosphide reacts with alkyl halides to give a mixture of di and trialkylheptaphosphines. Reac tions of tetraalkylammonium salts with the heptaphos phide trianion yield the asymmetric isomers of dialkyl heptaphosphide only. 7 Our attention has been attracted by the known reac tion of alkali metal phosphides with alkyl and aryl tosylates, which occurs under mild conditions to give the desired tertiary phosphines in good yields (Scheme 1). 8 Scheme 1 R 2 PNa + R-O-Ts R 2 P-R + NaO-TsAlthough this reaction works well in the alkylation of simplest phosphides, the possibility of applying it to polyphosphide systems has not been investigated to date.The goal of the present work was to study reactions of trisodium heptaphosphide (1) with alkyl tosylates, deter mine the factors that affect the yields and structures of the reaction products, and examine their structures by 31 P NMR spectroscopy. Results and DiscussionWe found that reactions of heptaphosphide 1 with alkyl tosylates (2 equiv.) give dialkylheptaphosphides 2 and 3 as the major products (Scheme 2). Scheme 2 R = Pr i (2), Bu i (3)The 31 P NMR spectrum of the reaction mixture shows five groups of signals at δ 52, -46, -124, -129, and -163, which indicates the formation of only one asymmetric isomer of sodium dialkylheptaphosphide. The signal at

Heating of a mixture of white phosphorus and sodium in diethylene glycol dimethyl ether in the presence of catalytic amounts of dibenzo 18 crown 6 affords a pure solution of sodium pentaphosphacyclopentadienide NaP 5 . One of the intermediate products is trisodium heptaphosphide Na 3 P 7 . The influence of the nature of a metal (Li, Na, K) on the formation of the pentaphosphacyclopentadienide anion was studied.Homopolyatomic clusters also named Zintl ions 1 and, in particular, metal polyphosphides, 2 attract keen atten tion of researchers. On the one hand, these compounds are intermediates in processes of elemental phosphorus transformation and, hence, studies of their structure and chemical properties allow deeper understanding of the mechanism of these reactions. 3 On the other hand, alka line metal polyphosphides containing phosphorus atoms in different oxidation states represent unique systems for the design of related complex polydentate molecules and clusters of potential practical significance. 4 Thus, the de velopment of new convenient methods for syntheses of alkaline metal polyphosphides is an important and ur gent task.The pentaphosphacyclopentadienide anion P 5 -(1) should be especially distinguished of the diversity of pres ently known alkaline metal polyphosphides. Anion 1 is the only polyphosphide with properties of an aromatic compound. According to the data of quantum chemical calculations, 5 this anion exists as a planar ring with six π electrons, thus satisfying the aromaticity principle. In addition, anion 1 is an isolobal analog 6 of the cyclo pentadienide anion (Cp -), being one of the most popular ligands in organometallic chemistry. This forms a good foundation for comparison of chemical properties of both anions and makes it possible to contribute to the solution of the fundamental problem of the chemistry of organo element compounds: the principle of diagonal relation ship between carbon and phosphorus. 7Several approaches to the generation of anion 1 exist ing only in solution are presently known. Heating of a mixture of alkaline metal dihydrophosphide MPH 2 (M = Li, Na, K) and elemental phosphorus 8-10 produced a mixture of polyphosphides from which a pure solution of MP 5 was isolated by low temperature recrystallization. However, a great amount of phosphine PH 3 is formed in this reaction, which requires special apparatus design of the synthesis. The reaction of white phosphorus with al kaline metals seems to be a more convenient method. However, reflux of a mixture of white phosphorus and sodium in diglyme 10 produces only a mixture of poly phosphides. The reaction of white phosphorus with so dium in tetrahydrofuran in the presence of equimolar amounts of crown ether also affords a mixture of poly phosphides from which sodium pentaphosphacyclo pentadienide was isolated in the pure state by low temperature recrystallization. 11 The formation of higher alkaline metal polyphosphides (Na 3 P 19 , Na 3 P 21 , etc.) with low solubility was mentioned in all studies on the topic.We assumed ...