Metal phosphinate polymers, structures

An X-ray structure study on [139] established the existence of the doubly bridged phosphinate linkage 32). Another structure study on a monomeric compound is available that also established the existence of a doubly bridged diphenyl phosphinate structure (139). These examples are to be weighed against the recent structural evidence discussed above for metal phosphinate polymers. 

Ring-opening polymerization (ROP) approaches have also been reported for the formation of coordination polymers. An early report in 1960 described the formation of beryllium polymers vith / -diketonate ligation, such as 7.55, by thermal ROP (Eq. 7.15) [105]. Structural characterization of the polymers vas based on IR and elemental analysis data. Based on their intrinsic viscosities in benzene and mechanical properties, it vas inferred that the polymers vere of high molecular veight. More recently, coordination polymers based on metal-phosphine ligation have been prepared. For example, ROP of 7.56 in the solid state occurs to form the silver polymer 7.57 (Eq. 7.16) [106]. 

When the acetylenic groups are in the para positions on the aromatic ring, condensation with a metal phosphine leads to a linear polymer as in (8.358), but if these groups are in the ortho position a cyclic tetrameric ring is produced as in (8.357) [33]. With three pendant acetylenic groups, dendritic-type structures can be obtained as in (8.356). 

One of synthetic approaches for the iron nanoparticles is based on the widely used decomposition of iron pentacarbonyl [19, 361, 362], The novelty of the approach is the surfactant system used. Studies with a number of strongly bound surfactants have resulted in decreased magnetic response, due to surface oxidation, disturbing the electronic structure of the surface atoms, or some other mechanism. With this in mind, ones chose to work with a weak surfactant, a p-diketone. P-diketones do have a history as adhesion promoters in bonds between metals and polymers [363], The limited reactivity of p-diketones is as an advantage the P-diketone is much weaker oxidizer than carboxylic acids or alcohols and will not oxidize iron, it is not as nucleophilic as phosphines, yet it is known to be capable of chelating iron. 

Poly(metal phosphinates) were prepared from phosphinic acid and metal ion such as Zn(II) or Cr(IlI) [41,42], These polymers contained tetrahedral Zn(II) centers and symmetric bridging 0,0 -phosphinate groups in polymeric structure. The zinc phosphinate structure (32) with alkyl chains on the phosphorus melted. 

In comparison with polymers 23 26, absorption and emission bands of unsupported Pd-Pd bonded polymers 28 30 are blue shifted (Table 6), which is consistent with the structural change about the metals. The latter are composed of two phosphines and one isocyanide ligand, whereas the formers exhibit two isocyanides and one phosphine ligand around the Pd center. 

The clusters [AuOs3(/A-X)(CO)10(PPh3)] have been attached to phosphine-functionalized silica for X = H or Cl (175,176) or polymer (styrene-divinylbenzene) for X = H (176). On both supports, the immobilized hyd-rido cluster was found to be inactive for alkene hydrogenation and isomerization, whereas the supported Cl-containing species catalyzed alkene hydrogenation. The different behavior was initially incorrectly attributed to different metal framework structures for the two clusters, but, in fact, both species adopt similar butterfly skeletal geometries (12,54). 

Transition metal complexes can be immobilized on organic polymers such as polystyrene-divinylbenzene, polypropylene, poly (vinyl chloride), etc., as well as on the surface of inorganic oxides such as silica, y-Al203, glass, and molecular sieves (cf. Section 3.1.1.3). The metal complexes are attached to the supports via phosphine (-PR2), amine (-NR2) or other groups (-SH, -CN) linked to organic or inorganic support, e. g. Structures 1 and 2, where M = Pt, Rh, Pd, Ru, or Ni. 

The insoluble alkynylsilver complexes are regarded as coordination polymers (RC=CAg)co with cross-linking between the metal atoms and the ethynyls of adjacent RC=CAg units. Donor molecules (L) such as tertiary amines, phosphines and arsines can partly break down the polymeric structure. Thus the reactions of PhC=CAg with isopropylamine, trimethyl-, triethyl- or triphenylphosphine and triethylarsine yield the 1 1 complexes of the composition [(L)AgC=CR]49-51. 

---