The syntheses and crystal structures of two iminolithium adducts: (Ph2CNLi·NC5H5)4, a tetrameric pseudo-cubane formed by stacking two (LiN)2 four-membered rings, and [But2CNLi·OP(NMe2)3]2, a dimer prevented sterically from stacking

D BARR, R SNAITH, W CLEGG, Robert Mulvey, K WADE

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Abstract

The syntheses and crystal structures of two iminolithium adducts [But2CNLi·OP(NMe2)3]2(1)[OP(NMe2)3= hexamethylphosphoramide (hmpa)] and (Ph2CNLi·NC5H5)4(2)(NC5H5= pyridine) are described. Adduct (1) contains a centrosymmetric planar (LiN)2 ring, with Li–N distances of 1.923(6) and 1.948(6)Å, and a ring angle at nitrogen of 75.4(3)°. Unexpectedly, the C2CN skeletal planes of its imino ligands are twisted 58.6(6)° with respect to the (LiN)2 ring plane, apparently to accommodate the bulky hmpa ligands, so preventing the (LiN)2 rings from stacking to form an (LiN)4 cubane structure. In contrast, adduct (2), with sterically compatible Ph2CN and NC5H5 ligands, has an (LiN)4 cubane structure with three distinct categories of metal–nitrogen distance (averaging 2.03,2.08, and 2.16 Å respectively) and ligand orientations that support an interpretation of this cubane in terms of two stacked (LiN)2 four-membered ring systems.
LanguageEnglish
Pages2141-2147
Number of pages7
JournalJournal of the Chemical Society, Dalton Transactions
Issue number9
DOIs
Publication statusPublished - Sep 1987

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Dimers
Crystal structure
Hempa
Ligands
Nitrogen
Metals

Keywords

  • tetrameric pseudo-cubane
  • dimer
  • crystal structures

Cite this

@article{6da95e3162a84df8a0960fca6a21ef01,
title = "The syntheses and crystal structures of two iminolithium adducts: (Ph2CNLi·NC5H5)4, a tetrameric pseudo-cubane formed by stacking two (LiN)2 four-membered rings, and [But2CNLi·OP(NMe2)3]2, a dimer prevented sterically from stacking",
abstract = "The syntheses and crystal structures of two iminolithium adducts [But2CNLi·OP(NMe2)3]2(1)[OP(NMe2)3= hexamethylphosphoramide (hmpa)] and (Ph2CNLi·NC5H5)4(2)(NC5H5= pyridine) are described. Adduct (1) contains a centrosymmetric planar (LiN)2 ring, with Li–N distances of 1.923(6) and 1.948(6){\AA}, and a ring angle at nitrogen of 75.4(3)°. Unexpectedly, the C2CN skeletal planes of its imino ligands are twisted 58.6(6)° with respect to the (LiN)2 ring plane, apparently to accommodate the bulky hmpa ligands, so preventing the (LiN)2 rings from stacking to form an (LiN)4 cubane structure. In contrast, adduct (2), with sterically compatible Ph2CN and NC5H5 ligands, has an (LiN)4 cubane structure with three distinct categories of metal–nitrogen distance (averaging 2.03,2.08, and 2.16 {\AA} respectively) and ligand orientations that support an interpretation of this cubane in terms of two stacked (LiN)2 four-membered ring systems.",
keywords = "tetrameric pseudo-cubane , dimer , crystal structures",
author = "D BARR and R SNAITH and W CLEGG and Robert Mulvey and K WADE",
year = "1987",
month = "9",
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language = "English",
pages = "2141--2147",
journal = "Journal of the Chemical Society, Dalton Transactions",
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TY - JOUR

T1 - The syntheses and crystal structures of two iminolithium adducts: (Ph2CNLi·NC5H5)4, a tetrameric pseudo-cubane formed by stacking two (LiN)2 four-membered rings, and [But2CNLi·OP(NMe2)3]2, a dimer prevented sterically from stacking

AU - BARR, D

AU - SNAITH, R

AU - CLEGG, W

AU - Mulvey, Robert

AU - WADE, K

PY - 1987/9

Y1 - 1987/9

N2 - The syntheses and crystal structures of two iminolithium adducts [But2CNLi·OP(NMe2)3]2(1)[OP(NMe2)3= hexamethylphosphoramide (hmpa)] and (Ph2CNLi·NC5H5)4(2)(NC5H5= pyridine) are described. Adduct (1) contains a centrosymmetric planar (LiN)2 ring, with Li–N distances of 1.923(6) and 1.948(6)Å, and a ring angle at nitrogen of 75.4(3)°. Unexpectedly, the C2CN skeletal planes of its imino ligands are twisted 58.6(6)° with respect to the (LiN)2 ring plane, apparently to accommodate the bulky hmpa ligands, so preventing the (LiN)2 rings from stacking to form an (LiN)4 cubane structure. In contrast, adduct (2), with sterically compatible Ph2CN and NC5H5 ligands, has an (LiN)4 cubane structure with three distinct categories of metal–nitrogen distance (averaging 2.03,2.08, and 2.16 Å respectively) and ligand orientations that support an interpretation of this cubane in terms of two stacked (LiN)2 four-membered ring systems.

AB - The syntheses and crystal structures of two iminolithium adducts [But2CNLi·OP(NMe2)3]2(1)[OP(NMe2)3= hexamethylphosphoramide (hmpa)] and (Ph2CNLi·NC5H5)4(2)(NC5H5= pyridine) are described. Adduct (1) contains a centrosymmetric planar (LiN)2 ring, with Li–N distances of 1.923(6) and 1.948(6)Å, and a ring angle at nitrogen of 75.4(3)°. Unexpectedly, the C2CN skeletal planes of its imino ligands are twisted 58.6(6)° with respect to the (LiN)2 ring plane, apparently to accommodate the bulky hmpa ligands, so preventing the (LiN)2 rings from stacking to form an (LiN)4 cubane structure. In contrast, adduct (2), with sterically compatible Ph2CN and NC5H5 ligands, has an (LiN)4 cubane structure with three distinct categories of metal–nitrogen distance (averaging 2.03,2.08, and 2.16 Å respectively) and ligand orientations that support an interpretation of this cubane in terms of two stacked (LiN)2 four-membered ring systems.

KW - tetrameric pseudo-cubane

KW - dimer

KW - crystal structures

U2 - 10.1039/DT9870002141

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JO - Journal of the Chemical Society, Dalton Transactions

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