Reactions of cis-[PtCI,(PMe,Ph),] with terminal alkynes RC,H (R = Ph or But) and diethylamine in the presence of CuCl (up to 0.35 rnol per rnol Pt) yielded the complexes cis-[ PtCuCI(C,R),( PMe,Ph),]. The crystal structure for R = But showed that both alkynyl ligands are (J bonded to Pt and q2 co-ordinated to the Cu which has an approximately trigonal-planar geometry. The Pt( C,R),CuCI system is distorted from planarity. Similar reactions, but with more CuCl (1 rnol per rnol Pt), led to trans-[P~CU,CI,(C,R),(PM~,P~)~] (R = But). Treatment of the compound [Pt(C,Ph),(dppe)] (dppe = Ph,PCH,CH,PPh,) with [Cu(MeCN),] [BF,] gave [PtCu(MeCN)(C,Ph),(dppe)] [BF,] which is believed t o be structurally analogous to the neutral chloro complex. An acetone-acetonitrile solution of this complex deposited crystals of [Pt,Cu(C,Ph),(dppe),] [ BF,]. The crystal structure of the latter contains orthogonal platinum co-ordination planes and each of the four alkynyl ligands is q2 coordinated to a Cu atom in an approximately tetrahedral environment involving only carbon. Alkynyl ligands can bridge metal centres in many ways. ' Even bridging between two metal atoms occurs in three distinct modes, A-C. There are many examples of mode A, which can be regarded as the standard form when both metal atoms are transition metals. Mode B is much less common; it has been found for aluminium s y ~t e m s ~. ~ and we have identified an example recently in a triosmium c l u ~t e r . ~, ~ The symmetrical form C is also fairly uncommon; the cluster [Ru,(p-C,Bu')-

Several metal complexes containing acetylacetone as a neutral ligand have been prepared by (1) the direct addition of acetylacetone to anhydrous metal halides, (2) the reaction of the usual acetylacetonate chelate with dry hydrogen bromide in dichloromethane containing free acetylacetone, or (3) the reaction of trichlorotris(tetrahydrofuran)chromium(III) with acetylacetone. Based on the magnetic data and electronic and infrared absorption spectra, structures of these complexes have been proposed: CoCl2(acacH) and ZnCl2 (acacH), tetrahedral; MnBr2(acacH)2, NiBr2(acacH)2, CrBr2(acac)(acacH), and CrCl2(acac)(acacH), octahedral. In the manganese(II) complex enolic molecules of acetylacetone are coordinated to the metal atom as unidentate ligands, while in all other complexes a ketonic molecule of acetylacetone is involved as a bidentate ligand.(2) Y. Nakamura and S.

By treating cis-Pt(CtCPh) 2 (dppe) (1) with Mn 2 (CO) 9 (CH 3 CN) in refluxing toluene, crosscoupling of alkynyl ligands occurs to afford mixed transition metal compound of 3,4-diphenyl-1,3-butadiyne, [Mn 2 Pt(µ 3 -η 1 :η 1 :η 2 :η 4 -PhCCCCPh)(CO) 6 (dppe)] (2) in 19-38% isolated yield. 2 has a structure formed by an unprecedented heterometal complexation of 1-manganacyclo-2,3,4-pentatriene. The Pt(II) acetylide, by treating with Ru 3 (CO) 9 (PPh 3 ) 3 , directly converts into a π-complex of 1,3-diyne, Pt(η 2 -PhCCCCPh)(dppe) (4), in 38% yield. By reacting π-alkyne compound Pt(η 2 -PhCC-CtCPh)(PPh 3 ) 2 with Fe(CO) 5 and Ru 3 (CO) 12 , bimetallic [FePt(µ 3η 1 :η 1 :η 2 -COC 4 Ph 2 )(CO) 3 (PPh 3 ) 2 ] (5a) and triangular cluster [MPt 2 (µ 3 -η 1 :η 1 :η 2 -PhCC-CtCPh)-(CO) 5 (PPh 3 ) 2 ] (6a) have successionally been isolated in considerable yields. A dimetallic analogue of alkyne [FePt{µ 2 -η 1 :η) Fe, 6d and iso-6d; R 1 ) R 2 ) OCOCH 3 , n ) 2, M ) Fe, 6e; M ) Ru, 6f} have consecutively been prepared. Crystal structures of five of the compounds have been determined.

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