Mono- and bis-(acetylacetonato) complexes of arene-ruthenium(II) and arene-osmium(II): variation of the binding mode of [[eta].sup.1]-acetylacetonate with the nature of the arene

The mono(acetylacetonato) complexes [MCl(O,O'-acac) ([[eta].sup.6]-arene)] (M = Ru, Os, arene = [C.sub.6][H.sub.6], 1,3,5-[C.sub.6][H.sub.3][Me.sub.3], [C.sub.6][Me.sub.6]; M = Os, arene = 1,2-[C.sub.6][H.sub.3][Me.sub.2], 1,2,3-[C.sub.6][H.sub.3] [Me.sub.3]), which are formed from [[M[Cl.sub.2] ([[eta.sup.6]-arene)].sub.2] and thallium or sodium acetylacetonate, react with thallium acetylacetonate to give bis(acetylacetonato) complexes [M(O,O'-acac)([[eta].sup.1]-acac)([[eta].sup.6]-arene)]. The [[eta].sup.1]-acac ligand is bound through the [gamma]-carbon atom for M = Ru, Os, arene = [C.sub.6][H.sub.6]; M = Os, arene = 1,2-[C.sub.6][H.sub.4][Me.sub.2], 1,2,3-[C.sub.6][H.sub.3][Me.sub.3] and through a keto-oxygen atom for M = Ru, Os, arene = 1,3,5-[C.sub.6] [H.sub.3][Me.sub.3], [C.sub.6][Me.sub.6], the difference being attributed to a combination of steric and electronic effects. Cationic ruthenium(II) derivatives [Ru(L)(O,O'-acac)([[eta].sup.6]-arene]+ (arene = [C.sub.6][H.sub.6], 1,3,5-[C.sub.6][H.sub.3][Me.sub.3], [C.sub.6][Me.sub.6]; L = DMSO, MeCN, py, P[Ph.sub.3]) and [Ru(CO) (O,O-acac)([[eta].sup.6]-arene]+ (arene = 1,3,5-[C.sub.6][H.sub.3] [Me.sub.3],[C.sub.6][Me.sub.6]), and neutral osmium(II) [[eta].sup.1]-acetato derivatives [Os([[eta].sup.1]-OAc) (O,O'-acac) ([eta].sup.6]-arene)] (arene = [C.sub.6][H.sub.6], 1,2-[C.sub.6] [H.sub.4][Me.sub.2], 1,2,3-[C.sub.6][H.sub.3][Me.sub.3], 1,3, 5-[C.sub.6][H.sub.3][Me.sub.3], [C.sub.6][Me.sub.6]) are also described. The molecular structures of the following complexes have been determined by X-ray crystallography: [Os(O,O'-acac) ([[eta].sup.1]-C-acac)([[eta].sup.6]-1,2-[C.sub.6][H.sub.4] [Me.sub.2])], triclinic, space group P [bar]1 (No. 2), a = 9.922(2), b = 9.974(2), and c = 11.001(2) [Angstrom], [alpha] = 68.33(1), [beta] = 64.18(1), and [gamma] = 62.38(1)[degrees], V = 849.0(3) [Angstrom], Z = 2; [Os(O,O'-acac)([[eta].sup.1]-O-acac)([[eta].sup.6]-1,3, 5-[C.sub.6][H.sub.3][Me.sub.3])], monoclinic, space group C2/c (No. 15), a = 16.032(4), b = 11.989(3), and c = [2.sub.1].562(7) [Angstrom], [beta]= 108.91(2)[degrees], V = 3921(2) [Angstrom], Z = 8; [Os([[eta].sup.1]-OAc)(O,O'-acac)([[eta].sup.6]-[C.sub.6][H.sub.6])], triclinic, space group P [bar]1 (No. 2), a = 8.368(4), b = 8.402(4), and c = 11.008(4) [Angstrom], [alpha] = 71.68(3), [beta] = 69.35(3), and [gamma] = 69.77(3)[degrees], V = 663.0(6) [[Angstom].sup.3] Z = 2. Key words: arene-ruthenium, arene-osmium, acetylacetone, crystal structures.