Alkyne complexes platinum compounds

As with alkenes, alkynes coordinate to platinum in both the zerovalent and divalen oxidation states. Since the chemistry of platinum alkyne complexes is less extensive than that c alkene complexes, this section is not subdivided into complexes of the two types. The divalen compounds of platinum will be covered first, followed by the complexes of platinum in a forms zerovalent oxidation state. 

These reactions can be used to prepare a novel series of complexes where cyclic alkynes can be stabilized by coordination to platinum(O).831,832 The compounds are feasible because coordination of a triple bond to platinum causes a distortion of the alkyne from linearity by displacement of the alkynic substituents back away from the platinum. Also these methods can be used to prepare platinum(O) alkyne complexes with substituents other than triphenylphosphine.833-836... 

Heterometal alkoxide precursors, for ceramics, 12, 60-61 Heterometal chalcogenides, synthesis, 12, 62 Heterometal cubanes, as metal-organic precursor, 12, 39 Heterometallic alkenes, with platinum, 8, 639 Heterometallic alkynes, with platinum, models, 8, 650 Heterometallic clusters as heterogeneous catalyst precursors, 12, 767 in homogeneous catalysis, 12, 761 with Ni—M and Ni-C cr-bonded complexes, 8, 115 Heterometallic complexes with arene chromium carbonyls, 5, 259 bridged chromium isonitriles, 5, 274 with cyclopentadienyl hydride niobium moieties, 5, 72 with ruthenium—osmium, overview, 6, 1045—1116 with tungsten carbonyls, 5, 702 Heterometallic dimers, palladium complexes, 8, 210 Heterometallic iron-containing compounds cluster compounds, 6, 331 dinuclear compounds, 6, 319 overview, 6, 319-352... 

According to reaction (a) mixed substituted platinum(0)complexes of the hitherto unknown type Ptl L1 and PtLL 2 (where L and L are phosphorus ligands) can be isolated and characterized by nmr spectroscopy. Instead of Ph3P other R3P derivatives and Ph3As can be used. Complex D is very labile. IR data give evidence for a a-coordination of the CS2ligands. With the double ylide RR N-P(S)=NR (reaction (c) ) the four-membered chelate complex E with pentavalent phosphorus of coordination number four is formed. Compound F is an example of the well characterized alkyne complexes (here with the phospha(III)azene ligand L). 

A theoretical study of the intermediates involved in the formation of phospha-propyne from pyrolysis of vinylphosphirane has led to a new route to phospha-alkynes. Thus, pyrolysis of trimethylsilyl(l-phosphiranyl)diazomethane has yielded MeaSiC = P, via an intermediate 1-phosphiranylmethylene . Regioselec-tivity in the [3 + 2] cycloaddition reaction between phosphaethyne and diazomethane has been studied by theoretical techniques , and further examples of reactions of this type described . Cycloaddition of phospha-alkynes with silylenes has also been reported. The primary phosphine 324 has been isolated from the addition of diethylphosphite to t-butylphosphaethyne. The chemistry of phospha-alkyne cyclotetramer systems has been reviewed and the first examples of platinum(II) complexes of such cage systems described. Aspects of the reactivity of coordinated phospha-alkynes have received further study, and a remarkable metal-mediated double reduction of t-butylphosphaethyne to the complexed fluorophosphine 325 described Phosphorus-carbon-aluminium cage structures have been isolated from the reactions of kinetically stable phospha-alkynes with trialkylaluminium compounds and new phosphaborane systems have been obtained from the reactions of phospha-alkynes with polyhedral boranes . Further studies of wo-phospha-alkyne coordination chemistry have appeared . The reactivity of the ion 326 has been explored. ... 

Alkyne complexes of platinum have also been prepared from 3,3,3-trifluoropropyne, and parameters for compounds [293] to [295] are given in Table XVII. (151) Parameters for the silylacetylene complex rra/ii-Pt(PEt3)2(Cl)(SiH2C]CCF3), 5—51-3 for the terminal CF3 group, with 5/(Pt-F) +23-7 Hz and 5/(F-H) 2-2 Hz, were obtained by heteronuclear double resonance. (162)... 

The platinum(0) complex [Pt(PhNO)(PPh3)2] reacts with C02 to afford the metallacyclic nitroso species [Pt 0N(Ph)C(0)0 (PPh3)2] (60), the first example of insertion of C02 into a Pt—N bond.186 Other unsaturated carbon compounds such as CS2 and electrophilic alkenes and alkynes react similarly. The diradical peril uoro-/V,/V -dimethylethane-l,2-bis(amino-oxyl) reacts readily by oxidative addition to the platinum(0) precursor Pt(PPh3)4 to afford the corresponding platinum(lI)-nitroso complex containing a seven-membered chelate ring (61). The resulting complex is stable in air for several days at room temperature.187... 

The rhodium-catalyzed cyclization/hydrosilylation of internal diyne proceeds efficiently with high stereoselectivity (Scheme 106). However, terminal diynes show low reactivity to rhodium cationic complexes. Tolerance of functionalities seems to be equivalent between the rhodium and platinum catalysts. The bulkiness of the hydrosilane used is very important for the regioselectivity of the rhodium-catalyzed cyclization/hydrosilylation. For example, less-hindered dimethylethylsilane gives disilylated diene without cyclization (resulting in the double hydrosilylation of the two alkynes), and /-butyldimethylsilane leads to the formation of cyclotrimerization compound. 

An unusual chloronitro(bipy)(N,N -dinitroso-l,2-ethylenediaminato)platinum(IV) complex has been prepared by nitrosation of [PtCl2(en)(bipy)]Cl2.1166 Similar arylnitroso complexes of platinum(0) can be formed from nitrosobenzene and an appropriate precursor platinum(O) complex (equation 363).1167 This compound reacts with C02, CS2, alkenes and alkynes to give megacycles (equation 364).1168... 

A number of reactions of platinum(O) complexes have been discussed in the earlier sections of this chapter. These reactions include protonation reactions of PtL3 to give PtHLJ, oxidative addition of HX to give PtHXL, replacement with carboranes, alkenes and alkynes (L1) to give complexes of type PtLjL. The most studied complex of platinum(O) is Pt(PPh3)3 and in Scheme 10 are outlined examples of the numerous reactions which this compound will undergo. 

Bis(alkyl) complexes, with mercury, preparation, 2, 428 Bis(alkylidene)s, in Ru and Os half-sandwiches, 6, 583 Bis(alkylimido) complexes, with chromium(VI), 5, 346 Bis(rj2-alkyne)platinum(0) complexes, preparation, 8, 640 Bis(alkynyl) complexes in [5+2+l + l]-cycloadditions, 10, 643 with manganese, 5, 819 with mercury, preparation, 2, 426 mononuclear Ru and Os compounds, 6, 409 with platinum, 12, 125 with platinum(II), 8, 539 with titanium(IV), 4, 643 with zirconium, 4, 722... 

Cyano compounds liquid crystals, 12, 278 in silver(III) complexes, 2, 241 Cyanocuprates, with copper, 2, 186 Cyano derivatives, a-arylation, 1, 361 Cyanosilanes, applications, 9, 322 Cyclic acetals, and Grignard reagent reactivity, 9, 53 Cyclic alkenes, asymmetric hydrosilylation, 10, 830 Cyclic alkynes, strained, with platinum, 8, 644 Cyclic allyl boronates, preparation, 9, 196 Cyclic allylic esters, alkylation, 11, 91 Cyclic amides, ring-opening polymerization, via lanthanide catalysis, 4, 145... 

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