Experimental, structural, and theoretical studies of diplatinum complexes containing bridging phenylethenylidene ligands including the excited-state chemistry and photophysics of photochemically generated species

Abstract

2417adapted version of D N M R~.~ NMR probe temperatures were calibrated by using the method of van Geet4' and are considered accurate to *2 K. 13C{lH) EXSY spectra were obtained with either broad-band or composite-pulse 'H decoupling, using the Bruker automation microprogram NOESY (Dl-~/2-D(hr/2-D9-~/2-FID-acquire). The data table was acquired by using 1024 words in the F2 dimension and 256 words in the F1 dimension zero-filled to 512.Spectral widths were typically 1 kHz, and recycle delays (Dl) typically 4-6 8. The initial value of the incremented delay DO was 3 ps. For the low-temperature experiments, a cycle of either 8 or 16 scans were acquired for each F2 FID, with total acquisition times of ca. 4-8 h. A random variation of *15% was applied to the mixing time delay t , (D9) to reduce any correlations arising from scalar coupling. Apodization was applied to all data seta before Fourier transform, using either n/6 shifted sine-bell or exponential line-broadening (LB = 2) functions. EXSY spectra were symmetrized about the F1 = F2 diagonal. For complex 4 the volume integrals, corresponding to the diagonal and off-diagonal elements of the intensity matrix, were obtained by integration of the submatrix rows of the EXSY spectra containing the most intense peaks (usually six to ten rows). For complex 3 integrations were carried out both in the above manner and also by using the box-integral routine of the Bruker AP2D display program. Errors in the integrals were estimated from the inte-(46) Kleier, D. A.; Binsch, G. QCPE 1970, 11, 165. (47) van Geet, A. L. Anal. Chem. 1970,42, 679.grated intensity of identical sized boxes in noise areas of the EXSY spectrum. There was satisfactory agreement between the derived rate data using either method. Individual exchange rate constants were obtained from the intensity matrix by using the program D Z D N M R .~~Due to the possibility that apodization functions could adversely affect relative line widths, and hence relative intensities, the effect of using (a) no apodization, (b) n/6 shifted sine-bell, and (c) Lorentz-Gaussian line narrowing on the data for 3 at 225 K was examined. Apart from the rates associated with the b/c/e tripodal rotation, which appear ill-conditioned in this analysis, there were no serious discrepancies. Rates for the exchanges associated with the PtL3 rotation varied from ca. 0.1 to 0.2 s-l, which are within the range of the reported rate errors. The discrepancies seen for the b/c/e exchange rate constants (which must be regarded as unreliable at 225 K) are attributed to experimental errors arising from the broadness of the diagonal peaks and cross-peaks associated with this process, overlap of some lgsPt satellites, and generally poor S/N ratios. In order to a ensure a reasonably constant temperature over the whole experiment, the low-temperature acquisitions were limited to a ca. 8 h time period, allowing only a maximum of 16 transients per DO increment. Acknowledgment. Dr. David Stephenson (Exeter) is thanked for a copy of t h e 2D EXSY kinetic anal...

Pt-Tetraethynylethene Molecular Scaffolding: Synthesis and Characterization of a Novel Class of Organometallic Molecular Rods

“…The amount of structural information gained from the 1 H NMR spectra (CDCl 3 ) was quite limited owing to signal overlap. A characteristic quintet‐like multiplet around δ =1.90–2.25 was observed for the CH 2 protons of the phosphane ligands, and results from a complex coupling pattern with { 195 Pt, 1 H}, { 31 P, 1 H} and { 1 H, 1 H} couplings 25, 26. In the 13 C NMR spectra (CDCl 3 ) of the shorter rods 3 a – c , all resonances of the vinylic carbon atoms between δ =128 and 133 were resolved, whereas the acetylenic resonances already overlapped at the stage of trimeric 3 c , which showed 18 out of the theoretically expected 26 resonances.…”

The luminescent and scintillation properties of YAlO3 and YAlO3:Ce single crystalline films grown by liquid phase epitaxy from BaO‐based flux

“…Detailed surveys of the luminescence of polynuclear metal alkynyl complexes have recently reported20, 21 that the first luminescent platinum( II ) complex containing an alkynyl ligand, the dinuclear platinum( II ) phenylethynylidene complex [Pt 2 (μ‐CCHPh)(CCPh)(PEt 3 ) 3 Cl], which dates back to 1989, was found to exhibit red‐orange luminescence at 77 K 83…”

Stereochemistry of Platinum Organometallics

“…There are eleven binuclear [74][75][76][77][78][79][80][81][82][83], three trinuclear [84][85][86] and three tetranuclear [87][88][89] derivatives which contain two crystallographically independent molecules within the same crystal and their structural parameters are given in Table 3.…”

“…The platinum in these derivatives are found in the oxidation states of zero [84,87], +1 [74], +2 [75,76,[79][80][81][82][83]89], and mixed valence Pt(I)(x2) plus Pt(II) [85] and Pt(II) plus Pt(IV) (x2) [86].…”