Preparation of doubly acetylide-bridged binuclear platinum-platinum and platinum-palladium complexes. Structures of [[(dppe)Pt(C.tplbond.CPh)2]Pt(C6F5)2] and (PMePh3)2[(C6F5)2Pt(.mu.-C.tplbond.CPh)2Pt(C6F5)2]

Homo‐ and Heteropolynuclear Platinum Complexes Stabilized by Dimethylpyrazolato and Alkynyl Bridging Ligands: Synthesis, Structures, and Luminescence

“…Thus, the absence of absorptions due to the NÀH bonds and the significant shifts of the ñA C H T U N G T R E N N U N G (C C) stretching vibrations to lower wavenumbers with respect to those of the starting compound 1 (2127, 2115 (1) versus 2023, 1984 (2); 2039 (3); 1948 cm À1 (4)) indicate that in all cases the substitution of the acidic hydrogen atoms (NÀH) by Cu I , Ag I , and Au I atoms has taken place and that these metal atoms are presumably interacting with the electron density of the alkynyl ligands. [79][80][81] The FAB + mass spectra of all complexes exhibit a high-intensity peak corresponding to [Pt 2 4 ] in agreement with a dimeric formulation that has been confirmed by X-ray crystallography (Figures 2-4). …”

“…This fact concerning the structure, that is in line with the lower (C C) vibration observed in the IR spectra (ñ = 1948 in complex 4 as opposed to 2039 cm À1 in complex 3), clearly points to a stronger Au-h 2 (acetylenic) bonding interaction, contrasting with the relatively low number of reported complexes of type bis(h 2 -alkynyl)Au. [103] The PtÀC, [67][68][69][70][71][72][79][80][81] PtÀN, [52,53,[73][74][75][76][77][78] and MÀN bond lengths [37, 38, 43-50, 52, 54, 55, 64, 92, 105-111] are similar to those observed in related pyrazolate complexes.…”

“…The structure of complex 6 has been also confirmed by X-ray crystallography. The IR spectra of compounds 5 and 6 confirm the substitution of the acidic hydrogen atoms (NÀH) by Pd II or Pt II species, since no absorptions due to the NÀH bonds are observed and the h 2 -coordination of these metal centers to the alkynyl ligands, [79][80][81] because the ñA C H T U N G T R E N N U N G (C C) absorptions, appear significantly shifted to lower wavenumbers in relation to the precursor (see Experimental Section).…”

“…[83][84][85] The CuÀN and PtÀN bond lengths are in the range of those found in pyrazolato copper(i) [36-42, 56, 57, 63, 92] and Pt II complexes. [52,53,[73][74][75][76][77][78] As expected [79][80][81] the Pt-C a C b -C Ph units deviate from linearity, this distortion being more pronounced at the C b atom (161.7(6)-167.5 (7)8) and the C a C b bond lengths are slightly elongated with respect to complex 1.…”

“…The structural details concerning the C CPh units are typical of m,h 2 (s,p) alkynyl bridging complexes. [79][80][81] In particular, the Pt-C a C b -C Ph units are not strictly linear (see Table 3) and the C a C b bond lengths are comparatively longer than for typical terminal alkynyl complexes. It is interesting to note that these C C distances are somewhat more elongated in the platinum-gold derivative (4) (average 0.052 in complex 4 versus 0.03 in complex 3) with re- [8] …”