Metal complexes of the neutral borane adduct (B2H4.2P(CH3)3)

Abstract

Metal Complexes of the Neutral Borane Adduct B2H4.2P(CH3)3 Sir:Bis(trimethylphosphine)-diborane(4) (I) reacted with zinc chloride and gave a complex with the formula 02• 2 4• 2P(CH3)3. Shown in Figure 1 is the structure of the complex as determined by single-crystal X-ray analysis.1 I is coordinated to zinc through two hydrogen bridge bonds. Earlier, the formation of the triborane cation B3H6*2P(CH3)3+ was reported from this laboratory.2 The cation was considered to be the result of the coordination of B2H4-2P(CH3)3 to the cationic species BH2+. This formalism of B2H4-2P(CH3)3 coordination was extended to that involving metals as the coordination centers and thus led to the isolation and char-

Zinc Halide and Alkylzinc Complexes of a Neutral Doubly Base‐Stabilized Diborane(4)

“…Like in 1, the ZnH 2 B 2 five-membered ring is almost planar. The Zn-B distance in 2 measures 220.0(2) pm in one and 221.5(2) pm in the other molecule within the unit cell and is thus considerably shorter than in 1 [3] (226.4/227.6 pm). With 183.4(4) and 184.1(4) pm, the B-B bonds in 2 are significantly elongated relative to the free diborane (4) [HB(μ-hpp)] 2 [177.2(3) pm].…”

“…The Cl-Zn-Cl angles of 122.34(3) and 119.08(3)°in 2 compare with 114.7(1)°in 1. [3] The angle BZn-B was measured to be 49.25(10)°/49.13(10)°.…”

“…With 183.4(4) and 184.1(4) pm, the B-B bonds in 2 are significantly elongated relative to the free diborane (4) [HB(μ-hpp)] 2 [177.2(3) pm]. [14] They also are longer than the B-B bond in 1 [3] [181. 4(6) pm].…”

“…The neutral boron hydride bis(trimethylphosphanyl)diborane(4), B 2 H 4 (PMe 3 ) 2 , and the related B 2 H 4 (PMe 2 CH 2 -PMe 2 ) (see Scheme 1) have been shown to be versatile ligands, which are generally bonded through two of the hydrido substituents to the metal center. Examples of structurally characterized complexes of this kind include [ZnCl 2 -{B 2 H 4 (PMe 3 ) 2 }] (1), [3] [Cu{B 2 H 4 (PMe 3 ) 2 }]I, [4] [M(CO) 4 -{B 2 H 4 (PMe 3 ) 2 }] (M = Cr, Mo or W), [5,6] and [Cr(CO) 4 ] 2 -[B 2 H 4 (PMe 2 CH 2 PMe 2 )]. [7] Unfortunately, the structures of the free ligands B 2 H 4 (PMe 3 ) 2 and B 2 H 4 (PMe 2 CH 2 PMe 2 ) are up to date unknown, so that a direct comparison of the structural changes upon coordination is not possible.…”

Investigation of the Stability of the M‐H‐B Bond in Borane σ Complexes [M(CO)5(η1‐BH2R⋅L)] and [CpMn(CO)2(η1‐BH2R⋅L)] (M=Cr, W; L=Tertiary Amine or Phosphine): Substituent and Lewis Base Effects

“…[1,2] From such a point of view, we have explored the coordination chemistry of simple boron hydrides, BH 3 ·L (L= NMe 3 , PMe 3 , PPh 3 ) [3][4][5][6][7][8] and B 2 H 4 ·2PMe 3 . [9][10][11][12] We thought that this work could bring the nature of the metal-boron interaction into light. During the course of study, we have synthesized borane s complexes [M(CO) 5 A C H T U N G T R E N N U N G (h 1 -BH 3 ·L)] (M = Cr, W; L = PMe 3 , PPh 3 , NMe 3 ), [3,4] [CpMn(CO) 2 A C H T U N G T R E N N U N G (h 1 -BH 3 ·L)] (L = PMe 3 , NMe 3 ), [5] and related compounds.…”