Platinum complexes ring conformation

A wide range of multidentate amine ligands coordinate to platinum. The conformational analysis of chelate ring systems by NMR has been reviewed by Hawkins, and platinum complexes are included in this work.959 Amine ligands with sulfur groups can also act as chelates, and this subject has also been reviewed.960... 

Similar bis(silyl) chelating platinum complexes have been obtained by the oxidative addition of disilanes H3SiSiH3 to the dihydride complex (dcpe)PtH2. A rapid addition of the disilane to the hydride afforded selectively complex 85 whereas a slow addition afforded a mixture of complexes 85 and 87, presumably through complex 86 via an a-silyl shift. X-ray determination indicates that the Pt2Si4 ring core adopts a chair conformation in 85 (Scheme 39)227. 

The dimetallic platinum complex [ (C6F5)2Pt 2(K2-pzTp)] has been characterized by NMR which shows the occurrence of a very fast intramolecular interconversion between the conformational isomers arising from the boat-like M(N-N)2B ring inversion (Fig. 2.131).528... 

The [Pt(Se4)2]2 complex (133) has been prepared by the reduction of the platinum(IV) species [Pt(Se4)3]2 with excess borohydride.328 The X-ray structure of the complex shows that each of the five-membered rings adopts a half-chair conformation, with the platinum coordination sphere exhibiting slight distortion from a square-planar geometry.329... 

Overlap Geometry A schematic representation of the proposed overlap geometry for proflavine intercalated into a deoxy pyrimidine(3 -5 )purine site is presented below with the (o) symbols representing the location of the phenanthridine ring protons. The mutual overlap of the two base pairs at the intercalation site involves features observed in the crystal structures of a platinum metallointercalator miniature dC-dG duplex complex (55) and the more recent proflavine miniature dC-dG duplex complex (48), as well as features derived in a linked-atom conformational calculation of the intercalation site in the proflavine DNA complex (51). [4]... 

Figure 7-60 shows the structure of the 3-ferrocenylpyridine-dichloroplatinum(ii) complex, [(t/ -C5H5)Fe(t/ -C5H4-m-C5H4N)]2PtCl2 [176]. The coordination around the platinum atom is also square-planar in this case. In both ferrocenyl ligands, the cyclopentadienyl rings assume a nearly eclipsed conformation. 

In conformity with the calculations the yicrz-fused heterocycles with a phosphorus atom proved to be quite stable. For instance, treating 1,8-dilithionaphthalene (18) with (A, A -diisopropylamino)dichlorophosphine afforded in a 75% yield a P-substituted naphtho[l,8-Z)c]phosphete (19) that took up tungsten pentacarbonyl to form a complex compound 20 (02AG(E)3897). The latter on further reaction with platinum tetratriphenylphosphinate and carbon monoxide suffers a recyclization of the four-membered ring into a five-membered one (20—>21). The reaction of... 

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