Control of the reactivity of
trans-[Mo2(cp)2(CO)(Y![[triple bond, length as m-dash]](https://www.rsc.org/images/entities/char_e002.gif)
Z)(µ
-SR)2]
(cp = η-C5H5;
YZ = CO or CN-) by the sulfur
substituents (R = Me, Pri, But, Ph
or CF3). Crystal structure of
trans-[Mo2(cp)2(CO)(CNMe)(µ-
SCF3)2]
Abstract
Reaction of
trans-[Mo
2
(cp)
2
(CO)
2
(µ-SR)
2
] (cp = η-C
5
H
5
;
R = Me, Pr
i
, Bu
t
, Ph or
CF
3
; syn and anti isomers) with cyanide ion
gave the corresponding cyanide complexes
trans-[Mo
2
(cp)
2
(CO)(CN)(µ-SR)
2
]
-
, except with R = Bu
t
where no reaction was observed. For R = CF
3
,
two isomers having a syn orientation of the sulfur substituents
were obtained. The nature of the R groups is shown to have a crucial
influence on the site of the reaction of the cyanide complexes with
Me
3
O
+
. Complexes where R = Me,
Pr
i
(syn and anti isomers) or Ph
(anti isomer) were S-methylated, whereas N-methylation was
observed for R = Ph (syn isomer) or
CF
3
(anti and both syn isomers). This is
ascribed to electronic effects of the R groups which control the site of
methylation by switching the reaction from orbital control
(S-methylation) to charge control (N-methylation). For
R = CF
3
, the R groups also affect the reaction
of the dicarbonyl precursor with a YZ substrate since the
preferred site of attack is different for
YZ = CN
-
and
YZ = RNC.
Z substrate since the
preferred site of attack is different for
YZ = CN
-
and
YZ = RNC.
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![[triple bond, length as m-dash]](https://www.rsc.org/images/entities/h2_char_e002.gif)
Z)(µ
-SR)2]
(cp = η-C5H5;
Y