sup 13 C and sup 31 P CP/MAS NMR studies of the polytopal ligand rearrangement process of tungsten tris(trimethylphospine) hexahydride in the solid state

Journal Article · Wed Apr 17 00:00:00 EDT 1991 · Inorganic Chemistry; (United States)

DOI:https://doi.org/10.1021/ic00008a047· OSTI ID:5641344

Heyes, S J; Green, M L.H.; Dobson, C M ^[1]

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1. Univ. of Oxford (England)

W(PMe{sub 3}){sub 3}H{sub 6} (1), an archetypal nine-coordinate transition-metal complex, has been studied in the crystalline state by variable-temperature {sup 13}C and {sup 31}P CP/MAS NMR spectroscopy. The NMR spectra are consistent with a tricapped-trigonal-prismatic geometry for the complex, with two phosphine ligands in eclipsed prismatic sites and the third capping the prismatic face opposite the other two. The two prismatic phosphines are shown to be on inequivalent sites. At temperatures above 340 K, exchange broadening shows the occurrence of ligand functionality interchange between the different phosphine environments. Analysis of these line shapes and magnetization-transfer data, in the slow limit of exchange, for the both {sup 13}C and {sup 31}P nuclei shows activation parameters of E{sub a} = 148.8 {plus minus} 15 kJ mol{sup {minus}1} and A = 6.6 {times} 10{sup 23} s{sup {minus}1} for the ligand-functionality-interchange process. The most likely mechanism involves a double-rearrangement mechanism with polyhedral edge stretches through a monocapped-square-antiprismatic geometry to a tricapped-trigonal-prismatic intermediate in which all phosphines occupy capping positions. This allows complete scrambling of the ligand functionality, in a manner such that the spatial movement of the phosphine ligands within the crystalline frame need only be relatively small. An additional dynamic process, involving a tripod reorientation of the PMe{sub 3}rotors, has been detected by dipolar broadening of the {sup 13}C NMR spectra. 31 refs., 10 figs., 2 tabs.

• OSTI ID: 5641344
• Journal Information: Inorganic Chemistry; (United States), Vol. 30:8; ISSN 0020-1669
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
ALKANES
MOLECULAR STRUCTURE
HYDRIDES
ORGANIC PHOSPHORUS COMPOUNDS
TUNGSTEN COMPLEXES
CARBON 13
EXPERIMENTAL DATA
NMR SPECTRA
PHOSPHORUS 31
CARBON ISOTOPES
COMPLEXES
DATA
EVEN-ODD NUCLEI
HYDROCARBONS
HYDROGEN COMPOUNDS
INFORMATION
ISOTOPES
LIGHT NUCLEI
NUCLEI
NUMERICAL DATA
ODD-EVEN NUCLEI
ORGANIC COMPOUNDS
PHOSPHORUS ISOTOPES
SPECTRA
STABLE ISOTOPES
TRANSITION ELEMENT COMPLEXES
400201* - Chemical & Physicochemical Properties
400202 - Isotope Effects
Isotope Exchange
& Isotope Separation