Manganese Complexes of 1,3,5-Triaza-7-phosphaadamantane (PTA):  The First Nitrogen-Bound Transition-Metal Complex of PTA

Abstract

The structures of two manganese(II) complexes of 1,3,5-triaza-7-phosphaadamantane (PTA) reveal the first transition-metal complexes of PTA in which the metal preferentially coordinates to a nitrogen and not the phosphorus of PTA. The coordination environment about the manganese was probed using X-ray crystallography (solid state) and EXAFS spectroscopy (solution).

Reactions of N-heterocyclic ligands with substitutionally labile organometallic complexes, [(η5-C5R5)Fe(CO)2E]BF4

“…Similar observations were reported by Hanic and Šubrtová in the structural study of C 6 H 12 N 4 ÁBH 3 [57] and by Frost et al in the structural study of PTAÁBH 3 [58]. For nitrogen coordinated PTA complexes, elongation of (N)C-N mainly results from alkylation or protonation of PTA, while metallation of PTA results in little or no change in (N)C-N distance [59]. Other selected bond distances and angles of 3a are listed in Table 1.…”

Synthesis and solid state structure of Co(II) complexes of OPTA

“…We have also reported the only example of an nitrogen bound PTA coordination complex involving a transition metal, MnBr 2 (OH 2 ) 2 (PTA) 2 , in which the phosphorus remains uncoordinated [5]. Reports of nitrogen bound PTA complexes are starting to appear regularly [3][4][5]18,19]. For example, Laguna and coworkers recently described a very interesting silver coordination polymer in which PTA is coordinated to three silver atoms in a j 3 (P,N,N) arrangement creating a polymeric structure [3].…”

“…We subsequently reported a coordination complex in which only an nitrogen atom of PTA was bound to the hard Lewis acid BH 3 , leaving an uncoordinated phosphorus atom [18]. We have also reported the only example of an nitrogen bound PTA coordination complex involving a transition metal, MnBr 2 (OH 2 ) 2 (PTA) 2 , in which the phosphorus remains uncoordinated [5]. Reports of nitrogen bound PTA complexes are starting to appear regularly [3][4][5]18,19].…”

“…Complex 1 was synthesized by a procedure similar to that published for a MnCl 2 complex previously described [5]. The cobalt salt (CoCl 2 Á 6H 2 O) and PTA were dissolved in acetone and refluxed for 30 min (Scheme 1).…”

“…For 35 years, it has been thought that PTA binds metals only through phosphorus. In recent years the number of papers describing the coordination chemistry of PTA [3][4][5][6][7][8] and derivatives [9][10][11][12][13][14][15][16][17] has increased dramatically. The first report of a nitrogen bound PTA metal complex appeared in late 2005; nitrogen coordination to silver was observed only after metal coordination of the phosphorus atom to ruthenium [18].…”