Platinum complexes isocyanide

In a three-component reaction, a cationic platinum isocyanide complex [(Ph3P)2Pt(CNR)Cl][BF4] is reacted with a /3-bromoamine and butyl lithium to give an imidazoldin-2-ylidene complex.This transformation can be a two-component reaction if the isocyanide ligand contains already the necessary amine functionality. This was shown for chromium, molybdenum, tungsten, and rhenium carbonyls. 

A significant proportion of all the papers that refer to platinum isocyanide complexes do so in the context of the reactivity of the bound isocyanide, and its conversion into a carbene ligand. All such papers are discussed in Section... 

The photophysics of some luminescent platinum isocyanide complexes was studied in detail. Such com-... 

In addition to the papers referenced above, crystallographic studies of a number of platinum isocyanide complexes have been undertaken, with stacking arrangements present in some structures,but absent in others. 

Since the initial report on the addition reactions of palladium(II) and platinum(II) isocyanide complexes by Badley et al. (S), a rather substantial number of further examples have been reported. These are summarized in Table II. 

Platinum(II) isocyanide complexes of the general formulas [PtL4], [PtL3X], and PtL2X2 and substituted derivatives thereof (L = RNC, X = halogen, H, R, etc.), have been studied recently and will be the main subjects of discussion. It may be observed that much work on complexes of the first and third molecular stoichiometries had been reported previously. 

Coco, S., Cordovdla, C., Donnio, B., Espinet, P., Garda-Casas, M.J. and Gudlon, D. (2008) Self-Organization of Dendritic Supermolecules, Based on Isocyanide-Gold(I), -Copper(l), -Palladium(II), and -Platinum(ll) Complexes, into Micellar Cubic Mesophases. Chemistry - A European Journal, 14, 3544-3552. 

The great majority of platinum(I) complexes are binuclear with monofunctional or bifunctional bridging groups. However, there is also a series of unsupported dimers with the general structure shown in (12). These are generally stabilized by phosphine, carbonyl, and isocyanide ligands.17 Dimeric hydride complexes can have terminal or bridging hydrides and these are discussed above in Section 6.5.2.1.4. 

The hexakis(methyl isocyanide) dimers, [Pt2(CNMe)6], undergo photolytic cleavage of the Pt—Pt bond to give 15-electron radicals, Pt(CNMe)3.94 Mixtures of platinum and palladium dimers give rise to heteronuclear complexes under photolytic conditions. Mixtures of normal and deuterium-labeled methyl isocyanide complexes reveal that the metal-ligand bonds undergo thermal redistribution.94... 

Platinum(I) isocyanide complexes are formed when Na2PtCl4 reacts with methyl isocyanide, and the product isolated by addition of AgPF6 (equation 116). The structure has two square planar platinums linked by a Pt—Pt bond, with the two Pt(CNMe)3 units perpendicular. The NMR spectrum shows that intramolecular rearrangements occur involving the tetrahedral deformation of one Pt center followed by rotation about the Pt—Pt bond.353 354... 

Platinum(IV) isocyanide complexes PtCU(CNR)2 and [PtCl2(CNR)2(PMe2Ph)2]2+ have been prepared by the addition of Cl2 to the corresponding platinum(II) compounds (equation 118).363 It is probable that the trans influence of the isocyanide ligand on platinum(IV) is greater than that of a tertiary phosphine. 

The most common reaction of platinum(II) isocyanides is their reaction with nucleophiles. This reaction is a useful one for the formation of platinum carbene complexes, and this will be discussed in the next section. 

Chemical routes to palladium(I) and platinum(I) isocyanide complexes have been devised. Addition of CNMe to an aqueous solution of [MC14]2-(M = Pd, Pt) resulted in the rapid formation of [M(CNMe)4]2+ cations, which were isolated as the hexafluorophosphate salts. On standing, however, the cations [M(CNMe)4]2+ slowly converted over 18 hr to [M CNMe ]2 ... 

In contrast, stepwise substitution reactions on M(CO)6 (M = Cr, Mo, W) have been achieved with a series of heterogeneous catalysts including co-balt(ll) chloride (27), activated charcoal (159), and platinum metals dispersed on oxide or carbon supports (31), to give mono-, di-, tri-, and complete substitution (124) in yields > 90%. Representative reaction times are given in Table II (159). The efficiency of the method was further demonstrated by the stepwise synthesis of the mixed isocyanide complexes m-Mo(CO)4(CNMe)(CNBu ) and /ac-Mo(CO)3(CNMeXCNBu )2 from Mo(CO)6 in <25 min in 85 and 95% yields, respectively (159). 

Typical platinum complexes that have recently been prepared from alcoholic KOH solutions and platinum isocyanide precursors are trans-Pt C(OMe)NR)(CHNR)(PEt3)2 (R = C6H4Me-p) (440, 451) and... 

A very interesting synthetic method was published in 1969 by Richards and co-workers (46). They found that, in the reaction of alcohols with certain isocyanide complexes sueh as those of platinum(II) ], an addition of the alkoxy group to the carbon atom as well as of the hydrogen to the nitrogen atom of the isocyanidc ligand occurs, and one thus obtains the corresponding carbene complexes ... 

J. S. Miller, and A. L. Balch, Preparation and Reactions of Tetrakis(methyl isocyanide) Complexes of Divalent Nickel, Palladium, and Platinum, Inorg. Chem. 11, 2069-2074 (1972). 

Platinum cluster complexes with Pt—Pt bond(s) having various oxidation states are well known, and many exist in low-valent oxidation state, such as a series of [PtsCCOeln and phosphine or isocyanide clusters 1-9). A platinum ion with an odd d electron tends to form a dimeric complex having a Pt—Pt single bond involving the unpaired electrons. Monovalent platinum forms dimeric cluster complexes with a d -d configuration (10-14) and tervalent platinum forms d -d ... 

Scheme 8. Polymerization of Isocyanides by a Dinuclear Palladium—Platinum //-Ethynediyl Complex...

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