Syntheses, structures, and mechanism of formation of trans-chlorohydrobis(trimethylphosphine)platinum(II) and trans-dihydrobis(trimethylphosphine)platinum(II). Energetics of cis-trans isomerization

1985 
The reaction between cis-PtCl/sub 2/(PMe/sub 3/)/sub 2/ (1) and Na(np) (np = naphthalene) under a H/sub 2/ atmosphere yields trans-PtHCl(PMe/sub 3/)/sub 2/ (2). Addition of a second 1 equiv of Na(np) produces cis- and trans-PtH/sub 2/(PMe/sub 3/)/sub 2/ (cis-3 and trans-3). Complex 3 was crystallized in the presence of np to yield trans-3.np. Both the latter complex and 2 were characterized by X-ray diffraction at -145 /sup 0/C. Crystals of 2 belong to the space group P2/sub 1//n with Z = 4, a = 10.241 (5) A, b = 19.012 (11) A, c = 6.300 (4) A, ..beta.. = 96.36 (1)/sup 0/, and V = 1227 (1) A/sup 3/. For the 1259 unique reflections that had I/sub 0/ > 3sigma(I/sub 0/) the Patterson solution and least-squares refinement led to final R = 0.063 and R/sub w/ = 0.082. Crystals of trans-3.np belong to the space group A2/m with Z = 2, a = 6.146 (2) A, b = 10.204 (3) A, c = 14.925 (4) A, ..beta.. = 99.17 (1)/sup 0/, and V = 936 (1) A/sup 3/. For the 864 unique reflections that had I/sub 0/ > 3sigma(I/sub 0/) solution by direct methods and least-squares refinement led to finalmore » R = 0.049 and R/sub w/ = 0.062. Complex 2 adopts a square-planar geometry, P(1)-Pt-P(2) = 176.0 (2)/sup 0/, with the Pt-Cl distance, 2.423 (6) A, significantly lengthened because of the trans influence of hydride. The trans-3.np complex exhibits no interaction between trans-3 and np, verifying the role of np as a crystallization agent. Electronic spectra of trans-3/np mixtures in n-hexane solvent did not provide evidence for a charge-transfer complex. Crystals of trans-3.np are extremely sensitive and lose H/sub 2/ under a N/sub 2/ atmosphere. They are stable under a H/sub 2/ atmosphere. 49 references, 3 figures, 5 tables.« less
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