Synthesis and crystal structure of tri(μ-carbonyl)bis[methyltris(1-pyrazolyl)gallato]dirhodium – benzene (1:1)

Abstract

, 633 (1984). The synthcsis, physical properties, and crystal structure of thc dirhodium spccics [ M C G~( N~C~H~) , ]~R~~(~-C O )~ containing thrcc carbonyl bridgcs are reported. Crystals of tri(~-carbonyl)bis~n~ethyltris(I-pyrazolyl)gallato]dirhodium -benzcnc (1 : I) are monoclinic, (I = 1 1.660(4), b = 15.29 17(7). c = 1 1.750(4) A, P = 1 19.09(1)", Z = 2, space group P 2 , . The structure was solved by conventional heavy-atom techniques and was refined by full-matrix Icast-squares procedures to R 0.030 and R,, = 0.033 for 2604 retlcctions with I 2 3u(1). The molecule contains a Rh-Rh single bond of 2.5818(8) A bridged by thrce CO ligands, the overall molccu$r symmctry being close to D,,,. Other important mcan structural parameters are: Rh-C = 2.007(10), Rh-N = 2.181(14) A, Rh-C-Rh = 80.1(5)", and Rh-C-0 = 140.0(7)".BRENDA M. LOUIE, STEVEN J. RETTIG, ALAN STORR et JAMES TROTTER. Can. J. Chem. 62, 633 (1984).On rapporte la synthkse. les propriCtCs physiques et la structure cristalline dcs dCriv@s du dirhodium [MeGa(NZC3H3)l2-Rh2(k-C0)? contenant trois groupcs carbonyles cn position de ponts. Les cristaux de tri(p-carbonyl)bis[mCthyitris(pyrazolyl-1)gallato]dirhodiumbenz6ne ( I : I) apparticnnent au groupe d'espace monoclinique P 2 , avcc ti = 11,660(4), I ? = 15,2917 (7) et c = 11,750(4) A. P = 119,09(1)", Z = 2. On a rksolu la structure par les techniques conventionnelles de I'atome lourd et on I'a affinke par la mkthodc dcs moindres carrcs (matrice cntiere) jusqu'a dcs valcurs de R = 0.030 et de R,,. = 0,033 pour 2604 rCflexions avec I 2 3a(l). La molCcule contient une liaison simple Rh-Rh dc 2,581 8(8) A maintenue en position de pont par trois ligands CO. la symCtric molCculairc globalc-cst voisine dc D3,,. Les principaux autres parametres structuraux moyens sont: Rh-C = 2,007(10), Rh-N = 2.18 l(14) A, Rh-C-Kh = 80.1(5)" et Rh-C-0 = 140,0(7)". [Traduit par le journal] IntroductionOur continuing investigations into the coordinating properties of pyrazolyl-gallate ligands have recently entered the fertile field of rhodium chemistry. Subtle differences between the cyclopentadienyl, C5H5-, and methyltris(1-pyrazolyl)gallate, MeGa(N2C,H,),-, ligands have been discussed in a previous publication (1). The present paper extends this theme in reporting the synthesis and structure of a unique dimeric rhodium system with three bridging carbonyl groups and end-capping MeGa(N?C,H,),-ligands, a compound having no counterpart in cyclopentadienyl rhodium carbonyl chemistry. Experimental Slarlitlg materialsAir-sensitive materials were handled in oxygen-frcc dry nitrogen. Tetrahydrofuran (THF) was dried by refluxing over sodium/benzophenone and used immediately following distillation. Benzene was dried by refluxing over molten potassium followed by distillation and methylene chloride by refluxing over PZOS prior to distillation.[Rh(CO)2C1]2 (Strem Chemicals) was sublimed itz vacuo before use. The sodium salt of the methyltris(1-pyrazoly1)gallate ligand, Na' [MeGa(N2C3H3),j. was prepared as a THF solution as described earlie...

Rhodium pyrazolate complexes as potential CVD precursors

“…The complex is stable in solution under an inert atmosphere, but quickly decomposes in the presence of air in solution and the solid state at room temperature. 16,27 To the best of our knowledge 4 is the first structurally characterized bis-pyrazolate complex of this type utilizing a trialkylphosphine exclusively as the neutral ligand. Complex 4 crystallizes in the space group P2 1 /c.…”

Synthesis and characterization of Pt(II) complexes containing the bidentate pyrazolylgallate ligand, [Me2Gapz2]−

“…This arrangement has been established recently for a number of bis pyrazolylgallate complexes of Rh (12,13), Re (14), Ir (15), and earlier for complexes of Mn, Mo (16), Ni (17,18), and Cu (19). Thus the observation of a singlet for the Me2M protons in the solution 'H spectra at room temperature of the platinum complexes I11 led us to suspect a fluxional process for the species in solution rather than the alternate explanation of a planar M (-N-N-),Pt sixmembered ring in the complexes.…”

Syntheses and reactivity of square-planar Rh(I) complexes, LRh(CO) (L = unsymmetric tridentate chelating pyrazolylgallate ligand). X-ray crystal structures of [Me2Gapz(OCH2CH2NH2)]Rh(CO) and [Me2Gapz(OCH2CH2NMe2)]Rh(COMe)I (pz = pyrazolyl, N2C3H3)

“…For example, the preparation of (qs-CSH5)Rh(C0)2 from [Rh(C0),C1I2 and Nak(C5HS)-has been known for some time (22). Similarly [HB(pz"),lRh(CO), can be prepared as stable yellow crystals in high yield (23,24), although it is interesting that the ligands MeGapz, and HBpz3-lead to the dinuclear rhodium species ( M e G a p~~)~R h~( p -c O ) , (2) and ( H B p~~)~R h~( p -c o ) (25). Our attempts to synthesize the analogous dicarbonyl rhodium species incorporating the "L" ligands 1 resulted instead in the isolation of stable, square-planar, 16-electron monocarbonyl complexes.…”

“…The novel compound, (MeGapz3)2Rh2(p-CO)3, incorporating symmetrical tridentate pyrazolylgallate ligands has also been described (2) …”