This chemical is called Allylidenetriphenylphosphorane, and its systematic name is triphenyl(prop-2-en-1-ylidene)-λ5-phosphane. With the molecular formula of C₂₁H₁₉P, its molecular weight is 302.35. In addition, its CAS registry number is 15935-94-1.

Other characteristics of the Allylidenetriphenylphosphorane can be summarised as followings: (1)ACD/LogP: 4.21; (2)# of Rule of 5 Violations: 0; (3)#H bond acceptors: 0; (4)#H bond donors: 0; (5)#Freely Rotating Bonds: 4; (6)Polar Surface Area: 9.81Ų; (7)Index of Refraction: 1.612; (8)Molar Refractivity: 96.13 cm³; (9)Molar Volume: 276.4 cm³; (10)Polarizability: 38.11×10^-24cm³; (11)Surface Tension: 43.6 dyne/cm; (12)Density: 1.09 g/cm³; (13)Flash Point: 227.3 °C; (14)Enthalpy of Vaporization: 68.41 kJ/mol; (15)Boiling Point: 452.3 °C at 760 mmHg; (16)Vapour Pressure: 6.1E-08 mmHg at 25°C. 

You can still convert the following datas into molecular structure: 
(1)SMILES: C(/C=P(c1ccccc1)(c2ccccc2)c3ccccc3)=C
(2)InChI: InChI=1/C21H19P/c1-2-18-22(19-12-6-3-7-13-19,20-14-8-4-9-15-20)21-16-10-5-11-17-21/h2-18H,1H2
(3)InChIKey: KTXDDSBSRMDZLM-UHFFFAOYAA
(4)Std. InChI: InChI=1S/C21H19P/c1-2-18-22(19-12-6-3-7-13-19,20-14-8-4-9-15-20)21-16-10-5-11-17-21/h2-18H,1H2
(5)Std. InChIKey: KTXDDSBSRMDZLM-UHFFFAOYSA-N