Reactions of acetylenes with noble metal carbonyl halides. 9. Preparation, chemical characterization and x-ray structural analysis of [cyclic] [Pt{C(O)CPr:CPrCPr:CPrCl}Cl]2 and the cyclocarbene derivative [Pt{CCPr:CPrCPr:CPrO}(PBu3)2Cl][PF6]

Abstract

Reactions of Acetylenes with Noble Metal Carbonyl Halides. 9.1 Preparation, Chemical Characterization, and X-ray Structural Analysis of [Pt{-C(=0)C(Pr)=C(Pr)C(Pr)=C(Pr)CI¡CI]2 and the Cyclocarbene Derivative [PtjCC(Pr)=C(Pr)C(Pr)=C(Pr)0¡(PBu3)2CI][PF6]

Two Forms of Bromo(cycloheptatrienylidene)bis(triphenylphosphine)platinum(II)

“…In (I) the dihedral angle between these planes is equal to 103.5 (3) ° , whereas in (II) it is 94.6 (5) °. These angles agree with observed values in several other ptXl-carbene complexes (Shubert, 1983;Michelin, Zanotto, Braga, Sabatino & Angelici, 1988;Garlaschelli, Malatesta, Panzeri, Albinati & Ganazzoli, 1987). The remaining geometrical features of both complexes are the same or very similar.…”

“…The seven-membered ring is planar in both compounds. The Pt--C 1 (carbene) bond lengths of 1.99 (1) and 2.03 (2) ,~ in (I) and (II), respectively, are in good agreement with each other and with corresponding distances in other square-planar Ptn-carbene complexes (Shubert, 1983;Michelin et al, 1988;Garlaschelli et al, 1987). The Pt--Br bond length of 2.513 (1) ~, is slightly lengthened compared with those of other ptlL-carbene complexes with the Pt--Br bond trans to the carbene (Michelin et at., 1988).…”

Synthesis and Characterization of Platina-β-diketones

“…The Pt−Cl distances [ d (Pt−Cl) = 2.430(3) and d (Pt−Cl‘) = 2.430(4) Å] are in the range of those known for chloro-bridged platinum compounds. − The Pt−C distances [ d (Pt−C1)/ d (Pt−C3) = 1.95(1) Å] are equivalent within one esd. They are in the range of platinum carbene complexes, whereas the Pt−C bond distances in acylplatinum complexes are generally somewhat longer. − The C−O bond lengths [ d (C1−O1) = 1.26(1) Å and d (C3−O2) 1.23(1) Å] are equivalent within the 3σ limit. Thus the C−O bond lengths correspond to those in the rhena-β-diketone, cis -[Re{(COMe) 2 H}(CO) 4 ] ( 4 ) [1.28(2) and 1.25(2) Å, respectively] .…”

Organic Syntheses via Transition Metal Complexes. 83.1 cis-1-Metalla-1,3,5-hexatrienes (Butadienylcarbene Complexes) of Tungsten via Ring Opening of Pyranylidene Complexes

“…While we were pursuing ring precursors of (conjugated) cis -1-tungsta-1,3,5-hexatrienes (CO) 5 WCXCRCRCRCRY (X, Y = OR‘, NR‘ 2 ; R = hydrogen, alkyl, aryl), our attention was drawn to 2 H -pyran-2-ylidene complexes, e.g., compound 3 , as potential starting materials. Among several routes available for the generation of pyranylidene complexes − the condensation of enolizable carbonyl compounds, e.g., 2,4-pentanedione ( 2 ), with a 1-alkynylcarbene complex, e.g., (CO) 5 WC(OEt)C⋮CPh ( 1 ), appeared to be the best suited in view of its high versatility …”