ARTICLE DOI: 10.1002/zaac.200900494
1,3-Bis(trimethylsilyl)-1,3,2-diazaphospha-[3]ferrocenophanes Bernd Wrackmeyer,*[a] Elena V. Klimkina,[a] and Wolfgang Milius[a] Dedicated to Professor Yuri N. Bubnov on the Occasion of His 75th Birthday Keywords: Ferrocenes; Ferrocenophanes; Aminophosphines; NMR spectroscopy; X-ray diffraction Abstract. The 2-tert-butyl, 2-phenoxy, and 2-diethylamino derivatives of 1,3-bis(trimethylsilyl)-1,3,2-diazaphospha-[3]ferrocenophane were prepared, and the molecular structure of the latter was determined by Xray diffraction. The phosphines could be oxidized by their slow reactions with sulfur or selenium, and the molecular structures of three
sulfides and one selenide were determined. In contrast, the synthesis of oxides was less straightforward. All new compounds were characterized in solution by multinuclear magnetic resonance methods (1D and 2D 1H, 13C, 15N, 29Si, 31P, and 77Se NMR spectroscopy).
Introduction Aminophosphines, which are well known for many years [1– 3], are attracting increasing interest as ligands for transition metal complexes [3, 4]. In this context, bulky substituents at nitrogen creating at least in part a rigid backbone may be useful, in order to stabilize a lower coordination number of the metal atom as a prerequisite of catalytic activity. At the same time, it might be an advantage to reduce the basicity of the nitrogen atoms. For these purposes, 1,1'-bis(trimethylsilylamino)ferrocene (2) [5], readily prepared from 1,1'-diaminoferrocene (1) [6, 7] should be a suitable starting material to accommodate the phosphorus atom between the two nitrogen atoms and form the 1,3,2-diazaphospha-[3]ferrocenophane unit. Recently, we have reported that this works fairly well without N-trimethylsilyl groups [8, 9] (Scheme 1, compounds 3–5). Indeed, the N-trimethylsilyl and other N-silyl derivatives have already proved useful in the synthesis of numerous 1,3-diaza2-element-[3]ferrocenophanes, in which either a main group element [5, 10–16] or a transition metal [17–22] takes the place between the nitrogen atoms. Although numerous N-silylaminophosphines were prepared [1–4, 23–26], cyclic derivatives were surprisingly rare [27], and only few were structurally characterized [28]. There are also rather few 29Si NMR spectroscopic data reported, in spite of the structurally diagnostic value of the geminal coupling constant 2J(31PN29Si), which indicates by its sign and magnitude the mutual orientation of the lone pair of electrons at the * Prof. Dr. B. Wrackmeyer Fax: +49-921-552157 E-Mail:
[email protected] [a] Laboratorium für Anorganische Chemie Universität Bayreuth 95440 Bayreuth, Germany Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/zaac.200900494 or from the author.
784
Scheme 1. 1,1'-Diaminoferrocenes 1, 2 and known 1,3,2-diazaphospha-[3]ferrocenophanes 3–5.
phosphorus atom and the N–Si bond vector [29, 30]. Some of the N-trimethylsilylaminophosphines have proved useful as starting material for valuable and unusual phosphorus/nitrogen compounds, e.g. the amino-iminophosphines [31]. Herein, we report on the synthesis, characterization, and some properties of 1,3-bis(trimethylsilyl)-1,3,2-diazaphospha-[3]ferrocenophanes.
Results and Discussion The two most convenient routes to the title compounds appear to be salt metathesis reactions, starting from 2 via the
© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Z. Anorg. Allg. Chem. 2010, 636, 784–794
1,3-Bis(trimethylsilyl)-1,3,2-diazaphospha-[3]erferrocenophanes Table 1.
13
C,
31
P,
29
Si,
15
N, and
77
8ab)
Se NMR spectroscopic dataa) of the 1,3-bis(trimethylsilyl)-2-R-1,3,2-diazaphospha-[3]ferrocenophanes 8–10.
8cb)
8d
9ab)
10ad)
10cb)
10db)
P–OPh P(S)OPh 139.2 {40.4} 70.1 {16.3}
P–NEt2 132.6
P(S)NEt2 77.2 {15.3}
1.8 (10.3) [57.4] 119.9 (9.7) Co 122.2 (1.8) Cp 129.7 (
