Complexes with Phosphine Ligands

Complexes with Oxygen Ligands and Oxo-Bridged Complexes Complexes with Schiff Base and Other Nitrogen Ligands Complexes with Phosphine and Arsine Ligands Complexes with Sulfur Ligands... 

Complexes with ligands derived from hydrogen sulfide and thiols Complexes with thioethers and related ligands Complexes with four-membered chelate rings Complexes with five- and six-membered chelate rings Complexes witii tiuourea and related neutral ligands Complexes with phosphine and arsine sulfides Complexes with Halides... 

Cyclization of 1,6-enynes. Pd(OAc)2, particularly when complexed with phosphine ligands, can effect cyclization of 1,6-enynes to a five-membered ring system. This cyclization, l- 2, provides a key step in a synthesis of the sesquiterpene sterepolide (3). ... 

Neutral (cyclobutadiene)Fe(CO)3 complexes undergo thermal and photochemical ligand substitution with phosphines, with alkenes such as dimethyl fumarate and dimethyl maleate and with the nitrosonium cation to generate the corresponding (cyclobutadiene)Fe(CO)2L complexes15. These types of complexes are presumably intermediates in the reaction of (cyclobutadiene)Fe(CO)3 complexes with perfluorinated alkenes and alkynes to generate the insertion products 266 or 267 respectively (Scheme 70)15,238. 

Pseudooctahedral coordination of rhenium(III) centers has also been found for mixed-ligand complexes with tertiary phosphines and A-heterocyclic thiols which coordinate as their neutral thione tautomers. A representative example with thiazoline-2-thiol (HSthiaz) has been characterized structurally. The paramagnetic complex [ReCl3(HSthiaz)2(PPh3)] (235) contains the HSthiaz ligands in trans position. ... 

In a concurrent study, a variety of rhodium-complexes with phosphine ligands were also examined for their suitability in the catalytic PK reaction [13cj. A key aspect of this work... 

Figure 1.68 Cold (111) complexes with phosphine ligands.

The activity of rhodium complexes with phosphine or phosphite ligands is about three to four orders of magnitude higher than that of cobalt catalysts.21-23 [RhH(CO)(PPh3)3] preformed or prepared in situ has proved to be the active species when triphenylphosphine is used as ligand. Despite the high cost of rhodium, the mild reaction conditions and high selectivities make rhodium complexes the catalyst of choice in hydroformylation. 

The most common nickel(O) complexes are those containing phosphorus, arsenic and antimony as donor atoms. Besides the Malatesta and Cenini book/1 which specifically deals with metal(O) complexes, nickel(O) complexes have been summarized in books and review articles which report complexes with phosphine, arsine and stibine ligands.31-37 Actually the nickel(O) complexes with these ligands amount to hundreds and the number of new complexes which are synthesized is increasing very rapidly, making nickel(0) phosphine chemistry a very extensive topic. 

Several synthetic procedures have been developed for the preparation of complexes with phosphines, arsines and stibines, and the most convenient or historically important ones are summarized in Table 3. They can be grouped in three main types of reaction the direct reactions of nickel with ligands, ligand replacement reactions and reduction reactions of nickel(H) complexes. 

Selected nickel(I) complexes with phosphines and arsines, together with relevant properties and synthetic routes, are reported in Table 21. In general, these nickel(I) complexes are air-unstable, especially when dissolved in solution consequently their preparation and handling require the exclusion of oxygen and, often, of moisture. The synthetic routes which afford nickel(I) complexes are strictly dependent on the nature of the phosphines and arsines and are not of general application, except in the case of some tripodal ligands. Most of the nickel(I)... 

A number of nickel(III) complexes with phosphines and arsines have been isolated, but nickel(IV) complexes with the same ligands are still rare, o-phenylenebisdimethylarsine (diars) and o-phenylenebisdimethylphosphine (diphos) have been found very efficient in stabilizing nickel(IV). Selected examples of nickel(III) and nickel(IV) complexes with phosphines and arsines are shown in Table 119. 

A number of molecular mechanics studies of metal-cyclopentadienyl complexes have been reported recently. The systems studied include linear metallocenes (in particular ferrocene), ferrocene derivatives (such as complexes with substituted cy-clopentadienyl ligands, bis(fulvalene)diiron complexes, ferrocenophanes and mixed-ligand complexes with carbonyls and phosphines), and nonlinear cyclopentadienyl complexes 8,153,221 231]. 

Reactions of cycloaurated complexes with phosphine ligands that lead to reductive coupling and the formation of biaryls are discussed separately in Section IV.K. 

---