2,5-Dithiahexane complexes

Reaction of ds-[PtCl2(C2H4)(py)] with cis-[Ru(bipy)2(CN)2] is first order in each compound, with a 2 value of 10.6 M s at room temperature in dimethylformamide solution. There is spectroscopic evidence for 1 1 and 1 2 binuclear products. " Two coalescence temperatures have been reported from variable-temperature NMR studies of the dithiahexane complex [Ru(dth)2Cl2]. Simple inversion at sulfur, a sufficient explanation for variable-temperature NMR spectra of, for instance, [M(dth)Cl4]" with M = Rh(III), Ir(III), Pt(IV) (q.v.), is clearly not a sufficient explanation here. "" ... 

Urea hydrolyzes about 3 x 10 times faster coordinated to [Rh(NH3)5] than in the uncoordinated state. This is a marked acceleration, but still very much less than the promotion of base hydrolysis of acetonitrile by [Ru(NH3)5] (cf. Section 8.3.2). Formation and aquation reactions of carbonato complexes are often coordinated ligand reactions, involving C-0 rather than Rh-0 bond formation and breaking. "" " Inversion at coordinated sulfur has an activation barrier (AG ) of 87.3 and 85.5 kJ moP in d(,-DMSO (at 383 and 378 K, respectively) in the dithiahexane complexes [Rh(dth)Cl4] and [Rh(dth)Br4) . As one might well expect, these barriers, though high, are less than that for the platinum(IV) analogue [Pt(dth)Cl4] " (cf. Section 8.7.2, and see Sections 8.3.1 and 8.6). 

The barrier to inversion at coordinated sulfur in the dithiahexane complex [Ir(dth)Cl4] is 63kJmor at 283 K in CDCI3/DMSO solution. Surprisingly, this is much lower than for the rhodium(III) analogue (Section 8.5.10) expectedly, the barrier is much lower than for the platinum(IV) analogue [Pt(dth)Cl4]. ... 

In 1962, Mannerskantz and Wilkinson described the reactions of [Mo(CO)4(2,5-dithiahexane)l with X2 (X = Br, I) to give the seven-coordinate complexes [MoX2(CO)3(2,5-dithiahexane)]. Treatment of the oxygen donor ligand complexes [M(CO)3(RPPh)] (M = Mo, W) RPPh = bis[(di-phenylphosphinyl)methyl]phenylphosphine oxide, [M2(CO)6(MDPO)] MDPO = methylenebis[diphenylphosphine oxide], and [M(CO)4(R... 

Cr(CO)6 is resistant to oxidation by halogens, unlike its Mo and W analogues. No reaction occurs with Br2 or I2 at RT CI2 effects oxidation to CrCla and phosgene. On the other hand, substitution of the carbonyl ligands by weaker tr-acid donors, such as bipyridine, thio ethers, or arsines, leads to complexes that are more easily oxidized. In some cases, such as Cr(CO)4L (L2 = 2,2 -bipyridine or 2,5-dithiahexane ), spectro-photometric changes and loss of CO are consistent with oxidation by Br2 and I2, though no isolable complex was obtained. If L is bis(l,2-dimethylarsino)benzene (diars), oxidation to Cr(diars)X3 (X = Br, I) occurs these Cr(III) complexes are likely dimers . ... 

In 1974 Travis and Busch reported the preparation of the red-brown [Co(14S4)] cation from interaction of 14S4 with [Co(MeCN)g] in nitromethane. The Co (II) complex probably resembles [Co(dth)2(OC103)2] (dth = 2,5-dithiahexane) [92], in which two CIO4 ions bind to the axial positions of a square-planar C0S4 unit. In light of the unusual properties of other Co-crown thioether complexes the electronic structures and electrochemical behavior of the [Co(14S4)]" complexes... 

ABSTRACT, The cyclic voltanraietric behaviour of four mononuclear copper(II) complexes and one binuclear copper(I) complex with the ligand 1,6-bis(3,5-dimethyl-l-pyrazolyl)-2,5-dithiahexane (bddh) was studied. Their oxidation-reduction properties will be discussed in terms of the possible relevance of these complexes as models of the Type 1 site of the blue-copper proteins. 

In the reaction of t-butylacetylene with [Pd(Cl)2(PhCN)2] the acetylene is consumed according to a first-order rate law up to the point where three equivalents of acetylene per Pd is reached after which the rate decreases by a factor of ten. Addition of 2,5-dithiahexane at the three-equivalents point gives complex (10) which has the structure illustrated, according to X-ray studies. This indicates that the first stage in the reaction, cis insertion into the Pd—Cl bond, is followed by a second cis insertion to give the (x-butadienyl ligand. Since three moles of acetylene are consumed at the point where the dithiahexane is added, complex (11) is considered to be the precursor of (10). 

Similarly, iodination of tetracarbonyl(2,5-dithiahexane)metal (Cr, Mo, W) complexes gives isolable seven-coordinate products [Ml2(CO)3(2,5-dithia-hexane)] only for molybdenum and tungsten. Reduction of these iodo compounds with lithium aluminum hydride forms unisolable materials with M—H bonds 45). 

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