The crystal structure of potassium [3,6-dimethyloct-4-yne-3,6-dioltrichloroplatinate(II)], K{Cl3PtII[(C2H5)(CH3)C(0H)–C [triple-bond] C–C(OH)(CH3)(C2H5)]}

Abstract

The crystal structure of the title compound has been determined from X-ray intensity data collected on a four-circle diffractometer with a 0-20 scan and graphite-monochromated Mo Ka radiation (20= 62°).( 2h, No. 14), Z=4, with a= 10-721(10), b=9.592(7),The crystals are monoclinic, space group P21/c C s c= 16"440(8) A and fl= 103"19(6) °. Crystal densities are Om= 1"95 and 0c=2.06 g cm -3. The structure was solved by the heavy-atom technique and refined by least-squares procedures to a final value of R = 0.084 and Rw=0.095, based on the 2291 observed reflexions with l>3a(1). The acetylenic bond is perpendicular to the plane of platinum coordination. The Pt-CI distance trans to the triple bond is longer [2.322 (7) IntroductionThis investigation is a part of the study of metalalkyne complexes which have the general formula Pt[Rt R2C(OH)-C-C-C(OH)R1R2]2. In a previous paper (Dubey, I975) the crystal structure of Pt[(CzHs)2C(OH) -C-C-C(OH) (C2Hs)z]2 has been studied (where RI and R2 groups are the same). The present structure was undertaken to determine the geometry of the molecule where R1 is different from R2. ExperimentalYellow prismatic crystals elongated along the a axis were obtained by crystallization of the compound from acetone solution at 0 °. The crystal density measured by flotation is in good agreement with the calculated value. The space group P2Jc was deduced from the systematic absences for hOl, l=2n+l, and 0k0, k= 2n + 1, together with the 2/m Laue symmetry observed photographically. Precise lattice parameters were obtained from a least-squares refinement of the 20, co, Z and ~0 angles of 15 well centred reflexions on a Syntex P1 automatic diffractometer using graphitemonochromated (take-off angle of 12 °) Mo Ke radiation. The crystal selected for X-ray intensity measurement was approximately 0.5 x 0.3 x 0.3 mm (the long axis parallel to the ~o axis). Intensity data were collected (20 < 62 °) at room temperature with the 0/20 scan mode and the reflexions were scanned at between 1° and 24 ° min -1 depending upon the peak intensity. The intensities of two standard reflexions, recorded after every 25 measurements to monitor the crystal stability, re-* Present address: Department of Chemistry-Biology, University of Quebec (Trois-Rivi6res), C.P. 500, Trois Rivi6res G9A 5H7, P. Quebec, Canada. mained essentially constant throughout the data collection. Out of 5234 measured intensities, 2291 were observed on the basis of 1> 3a(I).A standard deviation was assigned to each reflexion according to the formula:where S is the total counts collected during the scan, B1 and Bz are the number of counts collected for each background, and e is the ratio of scan time to total background time. The raw intensities were corrected for Lorentz and polarization factors and absorption corrections were applied according to the procedure described by Ahmed (1970). The corrected intensities were placed on an approximate absolute scale obtained from a Wilson plot. A summary of crystallographic data is given in Table 1.

Synthesis of complexes of the type cis-Pt(amine) (unsaturated ligand)Cl2 and crystal structure cis-Pt(methylaimne) (dimethylhexynediol)Cl2

“…As expected from IR spectroscopy, the compound is the cis isomer. The coordination around the Pt atom is square planar, and the mid-point X of C(4&-€ (5) The Pt--421 (2.300(3) and 2.302(3) A and the P t N (2.055((8) A) bonds are normal and agree well with published values found in aminochloroplatinum(II) complexes (10,11,14). There is no lengthening of the bond in trans position to the acetylenic ligand.…”

“…The Pt-42 distances are 2.138(9) and 2.11 8(9) A while the Pt-X distance is 2.039 A. The acetylenic ligand is perpendicular to the platinum plane as observed in other Pt -acetylenic glycol complexes (10,11). The angle between the best plane through C(3), C(4), C(5), and C(6) and the Pt plane is 92.4".…”

“…Crystal structure analysis of several platinum -unsaturated ligand complexes consistently showed that the olefin or alkyne was perpendicular to the platinum coordination plane (10)(11)(12)(13).…”

“…Compounds of the type K[Pt(un)C13] have been reported (8,(10)(11)(12) and their reactions with pyridine derivatives (py) give trans-Pt(py)(un)C12 because of the large trans effect of alkenes and alkynes. Much of the work reported on alkynes has been done with bulky ligands like (CH3)3C-C=C4(CH3)3 and glycols of the type R 2 C ( O H ) -C 4 ( O H ) R 2 since ligands like R m -H do not form stable Pt(I1) T complexes.…”

On the Equilibrium between Alkyne and Olefin Platinum(II) Complexes of Zeise’s Salt Type: Syntheses and Characterization of [K(18C6)][PtCl3(RC≡CR′)]

“…However, the exact nature of this compound was the subject of long discussions, which finally ended with the development of the corresponding bonding model by M. J. S. Dewar, J. Chatt, and L. A. Duncanson in 1951/1953 and the determination of the molecular structure by X-ray and neutron diffraction analysis in 1954 and 1975, respectively . Although numerous olefin complexes of Zeise’s salt type M I [PtCl 3 (R 2 CCR 2 )] (M I = alkaline metal; R = H, alkyl, aryl) have been synthesized, alkyne complexes of Zeise’s salt type, M I [PtCl 3 (RCCR′)], , could be obtained only to a limited extent. These complexes were mainly obtained for alkyne ligands with sterically demanding tert -butyl substituents or oxygen-functionalized substituents such as −C­(OH)­R 2 (R = alkyl, aryl) as well as phenyl substituents.…”