990. Complexes of acetylenes with platinum(II). Part II. Hydroxy- and methoxy-alkylacetylenes

Abstract

Complexes of the types M [PtCI,ac] and trans- [PtCl,ac(amine)], where M = Na or K, and ac = a tertiary a-hydroxyalkyl-or a-methoxyalkylacetylene, are described. The stabilities of the complexes depend on the nature of the ct-substituents of the acetylene.The infrared spectra of the complexes show that the CiC stretching frequency of the acetylenes is reduced by some 200 cm.-l on complex formation, and that the O-H stretching frequency of the hydroxyacetylenes is similarly reduced by 110-140 crn.-l. Evidence is presented for a structure in which the hydroxyacetylene is bonded to the platinum atom through its triple bond and also to the chlorine atoms through its hydroxyl groups. Dipole moments and pertinent features of the infrared and nuclear magnetic resonance spectra are recorded. Ally1 alcohol complexes have analogous structures. The methoxyacetylenes form relatively unstable complexes having the methoxyl groups turned away from the platinum atom.

Metal–acetylene complexes. II. Acetylene complexes of nickel, palladium, and platinum

“…AvC,, was much larger here and Chatt et al suggested (a), that the bonding of the acetylene to the metal (formally Pt(0)) was much stronger in (2) and (b), that in (2) the acetylene was coplanar (or nearly so) with the two P atoms and the ~t .…”

“…The second type of complex, (2), investigated by Chatt et al (1)(2)(3) showed a strong band at -1800 cm-' in the infrared spectrum which was ascribed to v,,, of the acetylene coordinated to the metal. AvC,, was much larger here and Chatt et al suggested (a), that the bonding of the acetylene to the metal (formally Pt(0)) was much stronger in (2) and (b), that in (2) the acetylene was coplanar (or nearly so) with the two P atoms and the ~t .…”

“…(1)(2)(3) deduced that the acetylenes were relatively weakly bonded to the metal, their criterion being Av,,, (v,,,(free acetylene) -v,,,(complexed acetylene)). In most disubstituted acetylenes v,,, occurs between 2190 and 2260 cm-' (1), in these complexes it varied from about 1994 to about 2046 cm-' The decrease in frequency observed, of about 200 cm-', was therefore comparable to that observed on complexing olefins to Pt(I1) in complexes such as Zeise's salt, KPtC,H4C13 (-150 cm-').…”

PLATINUM(II) COMPLEXES CONTAINING Α-Hydroxyacetylenes

“…, where ac = a tertiary a-hydroxyalkyl-or a-rnethoxyalkyl-acetone, have recently been discussed in some detail (1). Such compounds have been kno~vn for many !-ears (2,3) and the unexpected stability of the complex formed by the dihydroxyacetylene HO.…”

“…T h e 0-1-1 stretching frequency observed by Chatt et ul. (1) in their platinum(0) con~pound, in ~vhich only the triple bond is involved in the metal-ligand bond, is in exactly the same position a s the free ligand, and it is well established that drastic changes in the nature of the organic group t o which a hydroxyl group is attached produce very small changes in the 0-1-1 stretching frequency (6). The clear difference in the position of this hydrogen-bonded band in the free and bound glycol can only be accounted for if the hydroxyl groups are simultaneously linked to both the complex and the added base, and this is only possible if the oxygen of the hydroxyl groups is coordinated to the metal, leaving the hydrogen free to form a hydrogen bond to the base.…”