The syntheses and reactivity of the first rhodaboratranes, [RhX(PPh 3 ){B(mt) 3 }] (X ) Cl, H) and -C 8 H 12 ){B(mt) 3 }]Cl, are described in detail together with preliminary investigations of the mechanistic processes involved. The subsequent exploitation and circumvention of the lability of [RhCl(PPh 3 ){B(mt) 3 }] in the synthesis of a range of isonitrile, [Rh(CNR)(PPh 3 ){B(mtand dialkyldithiocarbamate, [Rh(S 2 -NEt 2 ){B(mt) 3 }]Cl, complexes is described, along with the attempted synthesis of [Rh(CN t Bu) 2 {B(mt) 3 }]Cl from [Rh(η 4 -C 8 H 12 ){B(mt) 3 }]Cl. Single-crystal X-ray structure determinations of [Rh(L)(L′){B(mt) 3 }]-Cl (L ) CN t Bu, CN(C 6 H 3 Me 2 -2,6), L′ ) PPh 3 ; L ) L′ ) PMe 3 ) are reported.

No abstract

The reaction of [PtCl 2 (PPh 3 ) 2 ] with Na[H-B(mt) 3 ] (mt ) methimazolyl) affords the platinaboratrane salt [PtH(PPh 3 ){B(mt) 3 }]Cl(Pt II fB), the first example of a metallaboratrane with the metal center in the +2 oxidation state. Base-induced dehydrochlorinationaffordsthefirstd 10 metallaboratrane,[Pt(PPh 3 ){B(mt) 3 }]-(Pt 0 fB), based on an unprecedented pentacoordinate platinum(0) geometry.

The platinaboratrane [Pt(PPh 3 ){B(mt) 3 }](PtfB) 10 (mt ) methimazolyl) is prone to oxidatiVe addition reactions with a range of substrates (Cl 2 , Br 2 , I 2 , HCl, CH 3 I) without disrupting the platinum-boron datiVe bond, as illustrated by the first structurally characterized platinaboratranes [PtH(PPh 3 ){B(mt) 3 }]Cl(PtfB) 8 and [PtI 2 {B(mt) 3 }](PtfB) 8 .The field of metallaboratrane chemistry 1 has grown rapidly in recent years, such that examples have now been isolated for all the metals of groups 8-10 (Chart 1). [2][3][4][5][6][7][8] The unique feature of a metallaboratrane is the inclusion of a metal-boron dative bond 9-11 within a cage structure. Examples of such compounds have been structurally authenticated for each of these metals, with the exception of platinum, although spectroscopic data ( 195 Pt and 11 B NMR) reliably attest to the presence of a direct PtfB interaction. 2i With this wealth of examples, it is noteworthy that very little is actually known about the reactivity of the MfB bond. Coligand substitutions have been reported for the rhodaboratrane [RhCl(PPh 3 )-{B(mt) 3 }], 2h while the putative thiocarbonyl derivative [RhH(CS)(PPh 3 ){BH(mt) 2 }] evolves spontaneously into the unusual CS-insertion product [RhH(PPh 3 ){SC(PPh 3 )BH-(mt) 2 }]. 2j Parkin's ferraboratrane [Fe(CO) 2 {B(mt tBu ) 3 }] reacts with chlorinated solvents to cleave the FefB bond with formation of the complex [FeCl{ClB(mt tBu ) 3 }], while [Fe(O 2 CPh){PhCO 2 B(mt tBu ) 3 }] is similarly obtained with benzoyl peroxide, 5b both reactions presumably proceeding via radical pathways. The platinaboratrane [Pt(PPh 3 ){B(mt) 3 }](PtfB) 10 (1) 2i has the metal formally in the zero oxidation state, 12 and accordingly, the electron-rich metal center might be expected to undergo oxidative addition reactions, assuming it is not deactivated by the presence of the PtfB bond. We report herein (i) a range of * To whom correspondence should be addressed. E-mail: a.hill@ anu.edu.au.(1) We have coined the term metallaboratrane to refer to a cage structure in which there is a transannular metal-boron dative bond. The majority of such compounds involve three supporting heterocyclic bridges; however, for those in which the MfB bond is only supported by two bridges, the "atrane" terminology is perhaps less appropriate: Hill, A. F.; Owen, G. R.; White, A. J. P.; Williams, D. White, J. L.; Tanski, J. M.; Zakharov, L. N.; Yap, G. P. A.; Incarvito, C. D.; Rheingold, A. L.; Rabinovich, D. Dalton Trans. 2004, 1626. (4) Senda, S.; Ohki, Y.; Yasuhiro, H.; Tomoko, T.; Toda, D.; Chen, J.-L.; Matsumoto, T.; Kawaguchi, H.; Tatsumi, K. Inorg. Chem. 2006, 45, 9914. (5) (a) Landry, V.; Melnick, J. G.; Buccella, D.; Pang, K.; Ulichny, J. C.; Parkin, G. Ayed, T.; Hussein, K.; Vendier, L.; Grellier, M.; Bouhadir, G.; Barthelat, J.-C.; Sabo-Etienne, S.; Bourissou, D. Dalton Trans. 2007, 2370. (8) (a) Bontemps, S.; Sircoglou, M.; Bouhadir, G.; Puschmann, H.; Howard, J. A. K.; Dyer, P. W.; Miqueu, K.; Bourissou, D. Chem. Eur. J. . (b) Sircoglou, M.; Bontemps...