ca01 only detailed ToC 1..24

126 Science of Synthesis 2.6 Complexes of Cr, Mo, and W without CO Ligands
Scheme 38 Syntheses from Complexes Containing Singly Bonded
Heteroelement Ligands [102,152–154]
W(Cp ∗ ) 2Cl 2
M(Cp) 2HLi
WMe 4
KOH (2 equiv)
THF, H2O R 1 PCl 2
+
PF 6 −
M = Mo, W; R 1 = 2,4,6-t-Bu 3C 6H 2
WCp ∗ Cl 4
1. Li2S2, THF, rt, 1 h
2. Ph4PBr, MeCN
61%
(Cp ∗ OH
) 2W
OH
PhNH2 (2 equiv)
CH2Cl2, rt, 2.5 h
87%
H
(Cp) 2M
PR1Cl − HCl
[Ph4P][WCp ∗ S3] 86
− H2O 36%
W
Me NPh
NHPh
Et3N, CH2Cl2 rt, 15 min
94%
W(Cp ∗ ) 2( O)
83
+
(Cp) 2M P
R1 85
PF 6 −
Me
W
NPh
NPh
84
tert-Butylammonium Trioxo(ç 5 -pentamethylcyclopentadienyl)tungstate(VI): [155]
An excess of t-BuNH 2 (0.08 mL, 0.76 mmol) and H 2O (0.04 mL, 2.2 mmol) was added to a
CH 2Cl 2 soln (25 mL) of [WCp*Cl(=O) 2] (140 mg, 0.36 mmol). The soln was stirred for 1 h,
dried (MgSO 4), and filtered through a pad of Celite. The solvent volume was reduced to
2–3 mLand hexane was added to induce precipitation of [WCp*(=O) 3][t-BuNH 3], which
was isolated; yield: 137 mg (86%).
2.6.7.2 Method 2:
From Other Complexes Containing Doubly Bonded Heteroelement Ligands
Compounds containing a metal-heteroatom double bond may be obtained from analogous
derivatives by exchanging the heteroelement ligand. This strategy is especially useful
for preparing imido and sulfido derivatives from more easily available oxo compounds.
In most cases, this method is used for the preparation of inorganic materials
that are subsequently converted into organometallic compounds via metathetical reactions
(see Section 2.6.1.5). [25] The new function (X) can be administered as either the diprotic
acid (H 2X) or the cumulene (O=C=X).
The use of the acid presents potential problems in the presence of sensitive hydrocarbyl
ligands. For particular systems, especially high oxidation state molybdenum and
tungsten compounds, the metal-carbon bonds are sufficiently covalent and resist protonolysis.
This is illustrated in the oxygen/sulfur exchange leading to products 87 in
Scheme 39. [156] The relative strengths of the metal-heteroelement double bonds are
against the exchange of oxygen by sulfur, whereas the weaker acidity of water vs hydrogen
sulfide favors the exchange. Concerning the oxo/imido exchange, the acidity criteri-