Platinum(II) Phosphido Complexes as Metalloligands. Structural and Spectroscopic Consequences of Conversion from Terminal to Bridging Coordination Corina Scriban, ² Denyce K. Wicht, ²,‡ David S. Glueck,* ,² Lev N. Zakharov, § James A. Golen, § and Arnold L. Rheingold § 6128 Burke Laboratory, Department of Chemistry, Dartmouth College, HanoVer, New Hampshire 03755, and Department of Chemistry and Biochemistry, UniVersity of California, San Diego, 9500 Gilman DriVe, La Jolla, California 92093 ReceiVed March 2, 2005 Treatment of the terminal phosphido complexes Pt(dppe)(Me)(PPh(R)) (R ) Ph (1), i-Bu (6)) with Pt(dppe)(Me)(OTf) gave the cationic µ-phosphido complexes [(Pt(dppe)(Me)) 2 (µ-PPh(R))][OTf] (R ) Ph (7), i-Bu (8)). Similarly, Pt((R,R)-Me-Duphos)(Me)(PPh(i-Bu)) (10) was converted to [(Pt((R,R)-Me- Duphos)(Me)) 2 (µ-PPh(i-Bu))][OTf] (11). A fluxional process in 8 and 11, presumably involving hindered rotation about the Pt-PPh(i-Bu) bonds, was observed by NMR spectroscopy; it resulted in two diastereomers for 8 and four for 11 at low temperature. Coordination of the metalloligand 10 to the [Pt((R,R)-Me-Duphos)(Me)] + fragment, yielding 11, resulted in structural changes at the Pt-phosphido group, whose geometry changed from distorted pyramidal to tetrahedral. Decomposition of 6 also gave the cation 8, while oxidation of 6 with H 2 O 2 gave the crystallographically characterized phosphido oxide complex Pt(dppe)(Me)(P(O)Ph(i-Bu)) (12). Introduction Forty years ago, Chatt and Davidson considered the possibility of terminal Pt-PPh 2 ligands: “it seems unlikely that they can exist in the Pt(II) series except under very special circumstances, the tendency to occupy bridging positions between Pt atoms being too strong.” 1 Avoiding labile ligands such as halides and monodentate phosphines is one way to fulfill the required special circumstances and prepare stable Pt(II) terminal phosphido complexes, such as the ones shown in Chart 1. 2 Such metal phosphido complexes contain pyramidal, nucleo- philic phosphorus centers, which can act as ligands to other metals. 4 For example, the reaction of 3 with [Pt(NCN)(H 2 O)] + (NCN ) 2,6-(CH 2 NMe 2 ) 2 C 6 H 3 ) gave the bimetallic complex 5. 3c We report here that Pt phosphido compounds such as 1 can also be converted into analogous µ-phosphido complexes, and we describe the spectroscopic and structural consequences of this change in coordination mode. * To whom correspondence should be addressed. E-mail: glueck@ dartmouth.edu. ² Dartmouth College. ‡ Present address: Department of Chemistry, Suffolk University, Boston, Massachusetts 02108. § University of California, San Diego. (1) Chatt, J.; Davidson, J. M. J. Chem. Soc. 1964, 2433-2445. (2) For other terminal Pt-phosphido complexes, see: (a) Allen, C. W.; Ebsworth, E. A. V.; Henderson, S. G.; Rankin, D. W. H.; Robertson, H. E.; Turner, B.; Whitelock, J. D. J. Chem. Soc., Dalton Trans. 1986, 1333- 1338. (b) Schaefer, H.; Binder, D. Z. Anorg. Allg. Chem. 1988, 560, 65- 79. (c) Mastrorilli, P.; Nobile, C. F.; Fanizzi, F. P.; Latronico, M.; Hu, C.; Englert, U. Eur. J. Inorg. Chem. 2002, 1210-1218. (d) Zhuravel, M. A.; Glueck, D. S.; Zakharov, L. N.; Rheingold, A. L. Organometallics 2002, 21, 3208-3214. (e) Kovacik, I.; Wicht, D. K.; Grewal, N. S.; Glueck, D. S.; Incarvito, C. D.; Guzei, I. A.; Rheingold, A. L. Organometallics 2000, 19, 950-953. (f) Wicht, D. K.; Kourkine, I. V.; Kovacik, I.; Glueck, D. S.; Concolino, T. E.; Yap, G. P. A.; Incarvito, C. D.; Rheingold, A. L. Organometallics 1999, 18, 5381-5394. (g) Wicht, D. K.; Glueck, D. S.; Liable-Sands, L. M.; Rheingold, A. L. Organometallics 1999, 18, 5130- 5140. (h) Wicht, D. K.; Kovacik, I.; Glueck, D. S.; Liable-Sands, L. M.; Incarvito, C. D.; Rheingold, A. L. Organometallics 1999, 18, 5141-5151. (i) Kourkine, I. V.; Sargent, M. D.; Glueck, D. S. Organometallics 1998, 17, 125-127. (j) Wicht, D. K.; Kourkine, I. V.; Lew, B. M.; Nthenge, J. M.; Glueck, D. S. J. Am. Chem. Soc. 1997, 119, 5039-5040. (k) David, M.-A.; Wicht, D. K.; Glueck, D. S.; Yap, G. P. A.; Liable-Sands, L. M.; Rheingold, A. L. Organometallics 1997, 16, 4768-4770. (l) David, M.- A.; Glueck, D. S.; Yap, G. P. A.; Rheingold, A. L. Organometallics 1995, 14, 4040-4042. (m) Scriban, C.; Glueck, D. S. J. Am. Chem. Soc. 2006, 128, 2788-2789. For a Pt-phosphenium complex, see: (n) Hardman, N. J.; Abrams, M. B.; Pribisko, M. A.; Gilbert, T. M.; Martin, R. L.; Kubas, G. J.; Baker, R. T. Angew. Chem., Int. Ed. 2004, 43, 1955-1958. (3) For 1, see: (a) Wicht, D. K.; Paisner, S. N.; Lew, B. M.; Glueck, D. S.; Yap, G. P. A.; Liable-Sands, L. M.; Rheingold, A. L.; Haar, C. M.; Nolan, S. P. Organometallics 1998, 17, 652-660. For 2, see: (b) Handler, A.; Peringer, P.; Muller, E. P. J. Chem. Soc., Dalton Trans. 1990, 3725- 3727. For 3 and 5, see: (c) Maassarani, F.; Davidson, M. F.; Wehman- Ooyevaar, I. C. M.; Grove, D. M.; van Koten, M. A.; Smeets, W. J. J.; Spek, A. L.; van Koten, G. Inorg. Chim. Acta 1995, 235, 327-338. For 4, see: (d) Cecconi, F.; Ghilardi, C. A.; Midollini, S.; Moneti, S.; Orlandini, A.; Scapacci, G. Inorg. Chim. Acta 1991, 189, 105-110. Chart 1. Pt(II) Terminal Phosphido Complexes 1-4 and Dinuclear μ-Phosphido Complex 5 Formed When 3 Acts as a Ligand 3 3370 Organometallics 2006, 25, 3370-3378 10.1021/om050149p CCC: $33.50 © 2006 American Chemical Society Publication on Web 06/09/2006