pubs.acs.org/Organometallics Published on Web 02/19/2010 r 2010 American Chemical Society Organometallics 2010, 29, 1339–1342 1339 DOI: 10.1021/om900764q Binuclear 1,2-Diphosphacyclopentadienyl Manganese(I) Complexes: Synthesis, Structure and Magnetic Properties Vasili Miluykov,* ,† Il’ya Bezkishko, † Dmitry Krivolapov, † Olga Kataeva, †,§ Oleg Sinyashin, † Evamarie Hey-Hawkins, ‡ Anupama Parameswaran, § Yulia Krupskaya, § Vladislav Kataev, § R€ udiger Klingeler, § and Bernd B€ uchner § † A.E. Arbuzov Institute of Organic and Physical Chemistry of the Russian Academy of Sciences, Arbuzov Street 8, Kazan 420088, Russian Federation, ‡ Institute of Inorganic Chemistry, Universit € at Leipzig, Johannisallee 29, 04103 Leipzig, Germany, and § IFW Dresden, POB 270116, D-01171, Dresden, Germany Received September 2, 2009 The reaction of Mn(CO) 5 Br with 1-trimethyltin-3,4,5-triphenyl-1,2-diphosphacyclopenta-2,4-diene leads to formation of binuclear manganese(I) complexes with bridging 1,2-diphosphacyclopentadienyl ligands exhibiting magnetic properties apparently similar to Mn(II) compounds due to intramolecular redistribu- tion of the electron density. Variation of peripheral ligands of binuclear complexes provides control over the magnitude of the magnetic moment, the contribution of the orbital magnetism, and the strength of the magnetic exchange. Introduction Electronic structure and magnetic properties of Mn-containing compounds continue to be a major research area because of the fascinating physical properties observed for these materials, such as single-molecule magnetism of multinuclear Mn complexes 1 or colossal magnetoresistance of manganese-based perovskite oxi- des. 2 These properties are closely related to the diversity of oxida- tion states and the effective magnetic exchange coupling between Mn ions provided by different short bridging ligands, such as O 2- , OH - , CN - ,N 3 - , RCOO - ,C 2 O 4 2- and pyrazolate. 3 Sur- prisingly, only a few data on the magnetism of complexes containing Mn(I) ions is available, though in this oxidation state Mn is isoelectronic to Fe 2þ , which is often found in a magnetic high-spin (HS) state. A rare example is a dimer complex of low- coordinated Mn(I) ions 4 with the open-shell configuration 4s 1 3d 5 , where the 4d-electrons built up a total HS state S = 5/2. We have supposed that a Mn(I) can be used for construction of molecular magnets by combination of Mn(I) ions with bridg- ing ligands capable of charge transfer. In this respect the 1,2- diphospha-3,4,5-triphenylcyclopentadienide anion 5 should com- bine the ability to bridge metal atoms with the feasibility of charge transfer similar to pyrazolate. 6 Results and Discussion Complexes 2a,b were prepared starting from the tin deri- vate 1 and Mn(I) bromide complexes (eq 1). It should be noted that formation of binuclear complexes is quite un- expected: similar reactions of the Sn derivate of 1,2,4-tripho- sphacyclopentadienide with [Mn(CO) 5 Br] resulted in 1,2,4- triphosphacymantrene only. 7 Acetonitrile ligands in 2b can be further easily replaced by PPh 3 to form 2c (eq 1). *Corresponding author. E-mail: miluykov@iopc.knc.ru. (1) (a) Gatteschi, D.; Sessoli, R. Angew. Chem., Int. Ed. 2003, 42, 268– 297. (b) Brockman, J.; Abboud, Kh.; Hendrickson, D. N.; Christou, G. Polyhedron 2003, 22, 1765–1769. (c) von H€ anisch, C.; Weigend, F.; Cl erac, R. Inorg. Chem. 2008, 47, 1460–1464. (2) Dagotto E. Nanoscale Phase Separation and Colossal Magnetore- sistance; Springer-Verlag: Berlin, 2002. (3) (a) Brandmayer, M.; Cl  erac, R.; Weigend, F.; Dehnen, S. Chem. ;Eur. J. 2004, 10, 5147–5157. (b) Escuer, A.; Aromí, G. Eur. J. Inorg. Chem. 2006, 4721–4736. (4) (a) Chai, J.; Zhu, H.; Stuck, A. C.; Roesky, H. W.; Magull, J.; Bencini, A.; Caneschi, A.; Gatteschi, D. J. Am. Chem. Soc. 2005, 127, 9201–9206. (b) Sorace, L.; Golze, C.; Gatteschi, D.; Bencini, A.; Roesky, H. W.; Chai, J.; Stuck, A. C. Inorg. Chem. 2006, 45, 395–400. (5) (a) Maigrot, N.; Avarvari, N.; Charrier, C.; Mathey, F. Angew. Chem., Int. Ed. Engl. 1995, 34, 590–592. (b) Miluykov, V.; Kataev, A.; Sinyashin, O.; L€ onnecke, P.; Hey-Hawkins, E. Organometallics 2005, 24, 2233–2236. (c) Bezkishko, I.; Miluykov, V.; Kataev, A.; Krivolapov, D.; Litvinov, I.; Sinyashin, O.; Hey-Hawkins, E. J. Organomet. Chem. 2008, 693, 3318–3320. (6) (a) Umakoshi, K.; Kojima, T.; Hun Kim, Y.; Onishi, M.; Nakao, Y.; Sakaki, S. Chem.;Eur. J. 2006, 12, 6521–6527. (b) Ranjan, S.; Lin, S.-Y.; Hwang, K.-C.; Chi, Y.; Ching, W.-L.; Liu, C.-S. Inorg. Chem. 2003, 42, 1248– 1255. (c) Jude, H.; Rein, F. N.; White, P. S.; Dattelbaum, D. M.; Rocha, R. C. Inorg. Chem. 2008, 47, 7695–7702. (d) Huang, H.-P.; Li, S.-H.; Yu, S.-Y.; Li, Y.-Z.; Jiao, Q.; Pan, Y.-J. Inorg. Chem. Commun. 2005, 8, 656–660. (7) Clark, T.; Elvers, A.; Heinemann, F. W.; Hennemann, M.; Zeller, M.; Zenneck, U. Angew. Chem., Int. Ed. 2000, 39, 2087–2091.