Alkyl, hydrido, and tetrahydroaluminato complexes of manganese with 1,2-bis(dimethylphosphino)ethane (dmpe). X-Ray crystal structures of Mn2(μ-C6H11)2(C6H 11)2(μ-dmpe), (dmpe)2Mn(μ-H)2AlH(μ-H)2AlH(μ-H) 2-Mn(dmpe)2, and...

Gregory S. Girolami, Christopher G. Howard, Geoffrey Wilkinson, Helen M. Dawes, Mark Thornton-Pett, Majid Motevalli, Michael B. Hursthouse

Research output: Contribution to journalArticlepeer-review

Abstract

full title:Alkyl, hydrido, and tetrahydroaluminato complexes of manganese with 1,2-bis(dimethylphosphino)ethane (dmpe). X-Ray crystal structures of Mn2(μ-C6H11)2(C6H 11)2(μ-dmpe), (dmpe)2Mn(μ-H)2AlH(μ-H)2AlH(μ-H) 2-Mn(dmpe)2, and Li4{MnH(C2H4)[CH2(Me)PCH 2CH2PMe2]2} 2·2Et2O Alkylation of MnBr2dmpe)2 [dmpe = 1,2-bis(dimethylphosphino)ethane] with MgBut2 leads to the t-butyl complex MnBut2(dmpe); alkylation with Mg(C6H11)2 gives the cyclohexyl-bridged dimer Mn2(μ-C6H11)2(C6H 11)2(μ-dmpe) (2). By contrast, alkylation with MgEt2 leads to the diamagnetic manganese(I) species, trans-MnH (C2H4) (dmpe)2. Interaction of the latter with LiBut leads to deprotonation of the dmpe ligand and formation of a complex, (4), of stoicheiometry Li2(MnH(C2H4)[CH2(Me)PCH 2CH2PMe2]2}·Et2O. A reduction of MnII to MnI also occurs in the interaction of MnBr2(dmpe)2 with LiAlH4 when the tetrahydroaluminate complex [Mn(AlH4)(dmpe)2]2 (5) is formed. Hydrolysis of (5) gives the volatile diamagnetic hydride MnH3(dmpe)2. The X-ray crystal structures of the complexes (2), (4), and (5) have been determined. In (2), the molecule, which has two-fold symmetry, has two manganese atoms each bound to one terminal related cyclohexyl group [Mn-C = 2.118(10) Å] and bridged asymmetrically by two symmetry related cyclohexyls [Mn-C = 2.256(9), 2.327(9) Å]. The Mn ⋯ Mn distance is quite short at 2.616(5) Å and the manganese atoms have a distorted tetrahedral co-ordination. In complex (4), two MnH(C2H4)(dmpe)2 units [Mn-H 1.44(4),Mn-C (av.) 2.121(5), Mn-P 2.213(3)-2.274(3) Å] have each lost two hydrogen atoms, one from each of two dmpe methyls, and the resulting four CH2 groups form multicentre alkyl bridges to a central Li4 tetrahedron [C ⋯ Li 2.20-2.36(I), Li ⋯ Li 2.46(1)-2.69(1) Å]. Two of the lithiums are co-ordinated by diethyl ether [ Li-O 2.053(8) Å]. The complex as a whole has C2 symmetry and the manganese(I) centre has a pseudo-octahedral geometry, although pentagonal bipyramidal is an alternative description if the ethylene is considered to occupy two co-ordination sites. Complex (5) is a centrosymmetric dimer in which two cis-octahedral MnH2(dmpe)2 units are bridged by a AlH-(μ-H)2AlH moiety via Al(μ-H)2Mn linkages. The two H atoms in the AlH2Mn bridge are closer to the Mn atoms [Mn-H = 1.61(3), 1.63(3) Å] than to the Al atoms [Al-H = 1.81(3), 1.81(3) Å]. The Al-H distances in the AlH2Al unit are 1.64(3) and 1.80(3) Å, while the terminal Al-H distance is 1.51(3) Å. The aluminium has trigonal bipyramidal co-ordination with one terminal hydrogen in an equatorial position.

Original languageEnglish (US)
Pages (from-to)921-929
Number of pages9
JournalJournal of the Chemical Society, Dalton Transactions
Issue number5
DOIs
StatePublished - Jan 1 1985
Externally publishedYes

ASJC Scopus subject areas

  • Chemistry(all)

Fingerprint Dive into the research topics of 'Alkyl, hydrido, and tetrahydroaluminato complexes of manganese with 1,2-bis(dimethylphosphino)ethane (dmpe). X-Ray crystal structures of Mn<sub>2</sub>(μ-C<sub>6</sub>H<sub>11</sub>)<sub>2</sub>(C<sub>6</sub>H <sub>11</sub>)<sub>2</sub>(μ-dmpe), (dmpe)<sub>2</sub>Mn(μ-H)<sub>2</sub>AlH(μ-H)<sub>2</sub>AlH(μ-H) <sub>2</sub>-Mn(dmpe)<sub>2</sub>, and...'. Together they form a unique fingerprint.

Cite this