Acetylenic Carbon-13 Chemical Shift Tensors for Diphenylacetylene and (η²-Diphenylacetylene)Pt(PPh₃)₂:  A Solid-State NMR and Theoretical Study

Abstract

The structure of (eta2-diphenylacetylene)Pt(PPh3) (2), as well as those of its dichloromethane and benzene solvates, is determined via X-ray crystallography. An investigation of the chemical shift (CS) tensors of the 13C-labeled carbons in Ph13C13CPh and (eta2-Ph13C13CPh)Pt(PPh3)2.(C6H6) is carried out via analysis of 13C NMR spectra from stationary solid samples. The principal components of the CS tensors as well as their orientations with respect to the 13C,13C internuclear vector are determined. DFT calculations of these CS tensors are in close agreement with the experimental values. For diphenylacetylene (tolane), the orientations and principal-component magnitudes of the alkynyl carbon CS tensors are comparable to those for other alkynyl carbons, although the CS tensor is not axially symmetric in this case. Coordination to platinum causes a change in the CS tensor orientation and a net increase in the isotropic chemical shift, resulting from a significant increase in two principal components (delta11 and delta33) while the third (delta22) decreases only slightly. The measured carbon CS tensors in the platinum complex bear a striking similarity to those of the alkenyl carbons in trans-Ph(H)C=C(H)Ph, and a short theoretical discussion of these observations is presented.

Synthesis and Structural Characterization of Group 10 Metal−Carboryne Complexes

“…The M−P distances are in the range 2.15−2.32 Å (Table ), which compare well with the 2.200(1) Å in (η 2 -C 6 H 4 )Ni(PCy 3 ) 2 , 2.140(1) and 2.152(1) Å in (η 2 -C 6 H 4 )Ni(Cy 2 PCH 2 CH 2 PCy 2 ), 2.151(2) and 2.176(2) Å in (η 2 -PhCCSiMe 3 )Ni(PPh 3 ) 2 , 2.328(1) and 2.342(1) Å in (η 2 -C 6 H 4 )Pd(PCy 3 ) 2 , 2.290(1) and 2.281(1) Å in (η 2 -PhCCPh)Pt(PPh 3 ) 2 , and 2.264(1) and 2.271(1) Å in (η 2 -cyclohexyne)Pt(PPh 3 ) 2 . The M···B(6)/B(3) distances in 1 − 5 and 7 − 10 fall in the region 2.58−2.81 Å.…”

Synthesis and Structures of Platinum(0) Alkyne Complexes with Extended π-Conjugated Systems

“…Figure depicts the top and side views of the X-ray crystal structure of 1c , which adopts a square-planar configuration around platinum, taking the two phosphorus atoms of DPCB-phen and the two acetylenic carbons of tolan-OMe as coordination atoms. The bond length between the acetylenic carbons (C1−C2 = 1.299(3) Å) is similar to those of [Pt(tolan)(dppbn)] (1.301(4) Å) and [Pt(tolan)(PPh 3 ) 2 ] (1.280(5) Å) . The Pt−C bond distances (2.038(2), 2.053(2) Å) are also comparable to those of dppbn (2.038(3), 2.041(3) Å) and PPh 3 (2.047(3), 2.048(3) Å) complexes.…”

Synthesis and structures of platinum diphenylacetylene and dithiolate complexes bearing diphosphinidenecyclobutene ligands (DPCB-Y)

“…Table 2 compares the structural parameters of 2a, 2c, 3b and 4a with those of phosphine analogues. [13][14][15][16] The C(1)-C(2) lengths of DPCB-Y complexes range from 1.277(8) to 1.299(3) A ˚; the values are similar to those of phosphine analogues (1.280(5)-1.308(9) A ˚). The bent back angles of the phenyl groups of tolan-X against the C(1)-C( 2) axis (i.e., the a values in Table 2) are also in a comparable range.…”